Covid-19 living Data

COVID-19 vaccine effectiveness
(Randomized evidence)

Methods

Latest news:Last search date July 30, 2023. No further screening is planned after this date. Extraction is ongoing for all pending studies.

Results of booster studies are available in the tables below and are updated on a monthly basis.

As of December 14, 2022, the COVID-NMA revised its protocol and discontinued the inclusion of prime vaccination trials in its analysis. The analysis presented on this page for prime vaccines compared to placebo or other vaccines includes trials that were identified and included up to December 14, 2022. A list of studies that were eligible up to this date but not extracted is provided in detail here .

The vaccine review "Efficacy and safety of COVID‐19 vaccines" included 41 preprints and published trials of 12 different COVID-19 used as prime vaccination and that were published before 5 November 2021.

meta-COVID

Perform your own analysis using COVID-NMA data for prime vaccination (last search date 14/12/2022), create and download your forest plots by clicking below:

COVID-19 BOOSTER DOSE VACCINATION: updated daily

Vaccine efficacy, immunogenicity and safety of:

First Boost

1st booster VS no booster (tables)

Reference	Type of prime vaccination	Prime schedule	Intervention 1	Intervention 2	Follow up days	Participants	GMT1(N1)	GMT2(N2)	GMR [95% CI]	Evaluated by
	A	B	C	D	E	Overall
Hall VG, 2021	RNA based vaccine	mRNA-1273	Boost mRNA-1273	Placebo	28	Transplant recipients	3,145 (60)	86 (57)	36.5 [ 12.9, 94]	Roche Elecsys
Vadrevu KM, 2022	Inactivated virus	BBV152	Boost BBV152	Placebo	28	Adolescents and adults	7,013 (80)	4,294 (87)	1.56 [1.06, 2.28]	ELISA

Immunogenicity
Geometric mean titre specific antibodies (D14)
Geometric mean titre neutralization assay against wild type (D14)

Reference	Type of prime vaccination	Prime schedule	Intervention 1	Intervention 2	Follow up days	Participants	GMT1(N1)	GMT2(N2)	GMR [95% CI]	Evaluated by	Risk of bias
											A	B	C	D	E	Overall
Vadrevu KM, 2022	Inactivated virus	BBV152	Boost BBV152	Placebo	28	Adolescents and adults	746 (80)	101 (87)	7.41 [2.96, 18.51]	PRNT
Zhang Y, 2023	Inactivated virus	CoronaVac	Boost ChAdTS-S	Placebo	14	Adults	290 (48)	5 (46)	56.8 [43.6, 74.1]	Micro-neutralisation assay
Zhang Y, 2023	Inactivated virus	CoronaVac	Boost RQ3013	Placebo	14	Adults	950 (46)	5 (46)	190.9 [145.8, 249.9]	Micro-neutralisation assay
Zhang Y, 2023	Inactivated virus	CoronaVac	Boost ZR202-CoV	Placebo	14	Adults	635 (47)	5 (46)	120.8 [92.6, 157.6]	Micro-neutralisation assay
Zhang Y, 2023	Inactivated virus	CoronaVac	Boost CoronaVac	Placebo	14	Adults	75 (46)	5 (46)	15.1 [11.5, 19.8]	Micro-neutralisation assay
Munro A, 2021 e	Non replicating viral vector	ChadOx1	Boost mRNA1273	Placebo	28	Adults, elderly, health care workers	2,368 (97)	80 (101)	26.98 [21.88, 33.26]	PNA
Munro A, 2021 e	Non replicating viral vector	ChadOx1	Boost CVnCov	Placebo	28	Adults, elderly, health care workers	373 (99)	80 (101)	5.06 [4.11, 6.23]	PNA
Munro A, 2021 e	Non replicating viral vector	ChadOx1	Boost BNT162b2 half dose	Placebo	28	Adults, elderly, health care workers	1,344 (103)	80 (101)	15.14 [12.32, 18.60]	PNA
Munro A, 2021 c	Non replicating viral vector	ChadOx1	Boost BNT162b2	Placebo	28	Adults, elderly, health care workers	1,621 (93)	70 (91)	21.58 [16.93, 27.51]	PNA
Munro A, 2021 c	Non replicating viral vector	ChadOx1	Boost VLA2001	Placebo	28	Adults, elderly, health care workers	202 (89)	70 (91)	2.68 [2.10, 3.43]	PNA
Munro A, 2021 c	Non replicating viral vector	ChadOx1	Boost VLA2001 half dose	Placebo	28	Adults, elderly, health care workers	147 (95)	70 (91)	2.01 [1.57, 2.55]	PNA
Munro A, 2021 c	Non replicating viral vector	ChadOx1	Boost Ad26.COV2.S	Placebo	28	Adults, elderly, health care workers	563 (95)	70 (91)	6.85 [5.37, 8.73]	PNA
Munro A, 2021 b	RNA based vaccine	BNT162b2	Boost ChadOx1	Placebo	28	Adults, elderly, health care workers	950 (98)	157 (111)	6.01 [4.87, 7.41]	PNA
Munro A, 2021 b	RNA based vaccine	BNT162b2	Boost Novavax	Placebo	28	Adults, elderly, health care workers	766 (94)	157 (111)	5.39 [4.35, 6.67]	PNA
Munro A, 2021 b	RNA based vaccine	BNT162b2	Boost Novavax half dose	Placebo	28	Adults, elderly, health care workers	606 (89)	157 (111)	3.50 [2.81, 4.36]	PNA
Munro A , 2021 a	Non replicating viral vector	ChadOx1	Boost ChadOx1	Placebo	28	Adults, elderly, health care workers	193 (98)	85 (90)	2.47 [1.96, 3.11]	PNA
Munro A , 2021 a	Non replicating viral vector	ChadOx1	Boost Novavax	Placebo	28	Adults, elderly, health care workers	727 (87)	85 (90)	8.86 [7.00, 11.22]	PNA
Munro A , 2021 a	Non replicating viral vector	ChadOx1	Boost Novavax	Boost ChadOx1	28	Adults, elderly, health care workers	727 (87)	193 (98)	8.86 [7.00, 11.22]	PNA
Munro A , 2021 a	Non replicating viral vector	ChadOx1	Boost Novavax half dose	Boost ChadOx1	28	Adults, elderly, health care workers	470 (86)	193 (98)	5.89 [4.64, 7.46]	PNA
Munro A , 2021 a	Non replicating viral vector	ChadOx1	Boost Novavax half dose	Placebo	28	Adults, elderly, health care workers	470 (86)	85 (90)	5.89 [4.64, 7.46]	PNA
Munro A, 2021 f	RNA based vaccine	BNT162b2	Boost mRNA1273	Placebo	28	Adults, elderly, health care workers	2,019 (91)	175 (98)	12.04 [9.95, 14.58]	PNA
Munro A, 2021 f	RNA based vaccine	BNT162b2	Boost CVnCov	Placebo	28	Adults, elderly, health care workers	487 (91)	175 (98)	2.57 [2.13, 3.12]	PNA
Munro A, 2021 f	RNA based vaccine	BNT162b2	Boost BNT162b2 half dose	Placebo	28	Adults, elderly, health care workers	1,339 (92)	175 (98)	6.91 [5.70, 8.37]	PNA
Munro A, 2021 d	RNA based vaccine	BNT162b2	Boost BNT162b2	Placebo	28	Adults, elderly, health care workers	1,789 (95)	205 (93)	8.35 [6.88, 10.14]	PNA
Munro A, 2021 d	RNA based vaccine	BNT162b2	Boost VLA2001	Placebo	28	Adults, elderly, health care workers	289 (91)	205 (93)	1.38 [1.14, 1.68]	PNA
Munro A, 2021 d	RNA based vaccine	BNT162b2	Boost VLA2001 half dose	Placebo	28	Adults, elderly, health care workers	234 (87)	205 (93)	1.22 [1.00, 1.49]	PNA
Munro A, 2021 d	RNA based vaccine	BNT162b2	Boost Ad26.COV2.S	Placebo	28	Adults, elderly, health care workers	1,441 (75)	205 (93)	7.84 [6.37, 9.64]	PNA
Wang X-Y, 2022	Inactivated virus	BBIBP-CorV or CoronaVac	Boost V-01	Placebo	14	Healthy adults	1,453 (199)	157 (221)	NR	Live SARS-CoV-2 neutralization assay.
Thuluva S, 2023 a	Non replicating viral vector	ChAdOx1	Boost BECOV2	Boost Placebo	28	Adults	6,317 (156)	1,877 (52)	*3.37 [2.00, ]**	Plaque Reduction Neutralization Titer (PRNT)

Number of patients analyzed in intervention 1; N2: Number of patients analyzed in intervention 2; GMT1: Geometric mean titre for intervention 1; GMT2: Geometric mean titre for intervention 2; N1GMR: Geometric mean ratio

Geometric mean titre neutralization assay against wild type (≥D90)

Reference	Type of prime vaccination	Prime schedule	Intervention 1	Intervention 2	Follow up days	Participants	GMT1(N1)	GMT2(N2)	GMR [95% CI]	Evaluated by	Risk of bias
											A	B	C	D	E	Overall
Vadrevu KM, 2022	Inactivated virus	BBV152	Boost BBV152	Placebo	180	Adolescents and adults	179 (31)	11 (37)	16.71 [3.31, 84.20]	PRNT
Zhang Y, 2023	Inactivated virus	CoronaVac	Boost ChAdTS-S	Placebo	90	Adults	76 (48)	4 (46)	18.48 [15.01, 22.76]	Micro-neutralisation assay
Zhang Y, 2023	Inactivated virus	CoronaVac	Boost RQ3013	Placebo	90	Adults	124 (47)	4 (46)	30.31 [23.33, 39.38]	Micro-neutralisation assay
Zhang Y, 2023	Inactivated virus	CoronaVac	Boost ZR202-CoV	Placebo	90	Adults	174 (47)	4 (46)	42.46 [32.36, 55.25]	Micro-neutralisation assay
Zhang Y, 2023	Inactivated virus	CoronaVac	Boost CoronaVac	Placebo	90	Adults	19 (46)	4 (46)	4.51 [3.61, 5.62]	Micro-neutralisation assay

Geometric mean titre neutralization assay against Omicron variant (D14)

Reference	Type of prime vaccination	Prime schedule	Intervention 1	Intervention 2	Follow up days	Participants	GMT1(N1)	GMT2(N2)	GMR [95% CI]	Evaluated by	Risk of bias
											A	B	C	D	E	Overall
Zhang Y, 2023	Inactivated virus	CoronaVac	Boost ChAdTS-S	Placebo	14	Adults	41 (48)	4 (46)	10.3 [7.6, 14.0]	Micro-neutralisation assay
Zhang Y, 2023	Inactivated virus	CoronaVac	Boost RQ3013	Placebo	14	Adults	247 (46)	4 (46)	62.4 [45.8, 85.1]	Micro-neutralisation assay
Zhang Y, 2023	Inactivated virus	CoronaVac	Boost ZR202-CoV	Placebo	14	Adults	104 (47)	4 (46)	26.0 [19.1, 35.4]	Micro-neutralisation assay
Zhang Y, 2023	Inactivated virus	CoronaVac	Boost CoronaVac	Placebo	14	Adults	8 (46)	4 (46)	2.0 [1.5, 2.7]	Micro-neutralisation assay
Hannawi S, 2022	Inactivated virus	BBIBP-CorV	Boost SCTV01C 20mcg	Placebo	28	Adults	840 (74)	58 (72)	14.4 [10.3, 20.2]	Plaque Reduction Neutralization Assay (PRNT50)
Hannawi S, 2022	Inactivated virus	BBIBP-CorV	Boost SCTV01C 40mcg	Placebo	28	Adults	901 (75)	58 (72)	15.0 [10.7, 21.1]	Plaque Reduction Neutralization Assay (PRNT50)

Geometric mean titre neutralization assay against Omicron variant (≥D90)

Reference	Type of prime vaccination	Prime schedule	Intervention 1	Intervention 2	Follow up days	Participants	GMT1(N1)	GMT2(N2)	GMR [95% CI]	Evaluated by	Risk of bias
											A	B	C	D	E	Overall
Zhang Y, 2023	Inactivated virus	CoronaVac	Boost ChAdTS-S	Placebo	90	Adults	12 (48)	4 (46)	3.1 [2.4, 4.0]	Micro-neutralisation assay
Zhang Y, 2023	Inactivated virus	CoronaVac	Boost RQ3013	Placebo	90	Adults	38 (47)	4 (46)	9.4 [6.72, 13.14]	Micro-neutralisation assay
Zhang Y, 2023	Inactivated virus	CoronaVac	Boost ZR202-CoV	Placebo	90	Adults	45 (47)	4 (46)	11.3 [8.32, 15.33]	Micro-neutralisation assay
Zhang Y, 2023	Inactivated virus	CoronaVac	Boost CoronaVac	Placebo	90	Adults	5 (46)	4 (46)	1.17 [1.01, 1.36]	Micro-neutralisation assay

Safety
Serious adverse events

Reference	Type of prime vaccination	Prime schedule	Intervention 1	Intervention 2	Follow up months	Participants	r1/N1	r2/N2	RR [95% CI]	Risk of bias
										A	B	C	D	E	Overall
Vadrevu KM, 2022	Inactivated virus	BBV152	Boost BBV152	Placebo	1	Adolescents and adults	0 / 80	0 / 87	NR
Tabarsi P, 2022	Any COVID-19 vaccine	Any Covid-19 vaccine	Boost SpikoGen	Placebo	0.5	Adults	0 / 250	0 / 50	NR
Zhang Y, 2023	Inactivated virus	CoronaVac	Boost ChAdTS-S	Placebo	3	Adults	0 / 48	3 / 47	0.14 [0.01 - 2.63]
Zhang Y, 2023	Inactivated virus	CoronaVac	Boost RQ3013	Placebo	3	Adults	0 / 47	3 / 47	0.14 [0.01 - 2.69]
Zhang Y, 2023	Inactivated virus	CoronaVac	Boost ZR202-CoV	Placebo	3	Adults	0 / 47	3 / 47	0.14 [0.01 - 2.69]
Zhang Y, 2023	Inactivated virus	CoronaVac	Boost CoronaVac	Placebo	3	Adults	0 / 46	3 / 47	0.15 [0.01 - 2.74]
Moreira E D, 2022	RNA based vaccine	BNT162b2	Boost BNT162b2	Placebo	2.5	Adults and adolescents	16 / 5055	24 / 5020	0.66 [0.35 - 1.24]
Sung J, 2022	Any COVID-19 vaccine	2 doses BNT162b2 or BBIBP	Boost Recombinant inactiv Bacillus subtilis spores	Boost active adjuvant	1.2	Healthy adults	0 / 9	0 / 7	NR
Hannawi S, 2022	Inactivated virus	BBIBP-CorV	Boost SCTV01C 20mcg	Placebo	1	Adults	0 / 79	0 / 75	NR
Hannawi S, 2022	Inactivated virus	BBIBP-CorV	Boost SCTV01C 40mcg	Placebo	1	Adults	0 / 80	0 / 75	NR
Munro A, 2021 e	Non replicating viral vector	ChadOx1	Boost mRNA1273	Placebo	2.7	Adults, elderly, health care workers	1 / 112	0 / 114	3.05 [0.13 - 74.16]
Munro A, 2021 e	Non replicating viral vector	ChadOx1	Boost CVnCov	Placebo	2.7	Adults, elderly, health care workers	0 / 119	0 / 114	NR
Munro A, 2021 e	Non replicating viral vector	ChadOx1	Boost BNT162b2 half dose	Placebo	2.7	Adults, elderly, health care workers	0 / 116	0 / 114	NR
Munro A, 2021 c	Non replicating viral vector	ChadOx1	Boost BNT162b2	Placebo	2.7	Adults, elderly, health care workers	0 / 106	1 / 105	0.33 [0.01 - 8.01]
Munro A, 2021 c	Non replicating viral vector	ChadOx1	Boost VLA2001	Placebo	2.7	Adults, elderly, health care workers	3 / 109	1 / 105	2.89 [0.31 - 27.34]
Munro A, 2021 c	Non replicating viral vector	ChadOx1	Boost VLA2001 half dose	Placebo	2.7	Adults, elderly, health care workers	0 / 111	1 / 105	0.32 [0.01 - 7.66]
Munro A, 2021 c	Non replicating viral vector	ChadOx1	Boost Ad26.COV2.S	Placebo	2.7	Adults, elderly, health care workers	1 / 108	1 / 105	0.97 [0.06 - 15.34]
Munro A, 2021 b	RNA based vaccine	BNT162b2	Boost ChadOx1	Placebo	2.7	Adults, elderly, health care workers	0 / 109	1 / 118	0.36 [0.01 - 8.76]
Munro A, 2021 b	RNA based vaccine	BNT162b2	Boost Novavax	Placebo	2.7	Adults, elderly, health care workers	1 / 114	1 / 118	1.04 [0.07 - 16.35]
Munro A, 2021 b	RNA based vaccine	BNT162b2	Boost Novavax half dose	Placebo	2.7	Adults, elderly, health care workers	2 / 112	1 / 118	2.11 [0.19 - 22.91]
Munro A , 2021 a	Non replicating viral vector	ChadOx1	Boost ChadOx1	Placebo	2.7	Adults, elderly, health care workers	1 / 111	0 / 109	2.95 [0.12 - 71.54]
Munro A , 2021 a	Non replicating viral vector	ChadOx1	Boost Novavax	Placebo	2.7	Adults, elderly, health care workers	0 / 115	0 / 109	NR
Munro A , 2021 a	Non replicating viral vector	ChadOx1	Boost Novavax	Boost ChadOx1	2.7	Adults, elderly, health care workers	0 / 115	1 / 111	0.32 [0.01 - 7.82]
Munro A , 2021 a	Non replicating viral vector	ChadOx1	Boost Novavax half dose	Boost ChadOx1	2.7	Adults, elderly, health care workers	0 / 108	1 / 111	0.34 [0.01 - 8.32]
Munro A , 2021 a	Non replicating viral vector	ChadOx1	Boost Novavax half dose	Placebo	2.7	Adults, elderly, health care workers	0 / 108	0 / 109	NR
Munro A, 2021 f	RNA based vaccine	BNT162b2	Boost mRNA1273	Placebo	2.7	Adults, elderly, health care workers	0 / 110	0 / 112	NR
Munro A, 2021 f	RNA based vaccine	BNT162b2	Boost CVnCov	Placebo	2.7	Adults, elderly, health care workers	1 / 106	0 / 112	3.17 [0.13 - 76.94]
Munro A, 2021 f	RNA based vaccine	BNT162b2	Boost BNT162b2 half dose	Placebo	2.7	Adults, elderly, health care workers	0 / 110	0 / 112	NR
Munro A, 2021 d	RNA based vaccine	BNT162b2	Boost BNT162b2	Placebo	2.7	Adults, elderly, health care workers	1 / 109	0 / 109	3 [0.12 - 72.84]
Munro A, 2021 d	RNA based vaccine	BNT162b2	Boost VLA2001	Placebo	2.7	Adults, elderly, health care workers	0 / 110	0 / 109	NR
Munro A, 2021 d	RNA based vaccine	BNT162b2	Boost VLA2001 half dose	Placebo	2.7	Adults, elderly, health care workers	1 / 110	0 / 109	2.97 [0.12 - 72.18]
Munro A, 2021 d	RNA based vaccine	BNT162b2	Boost Ad26.COV2.S	Placebo	2.7	Adults, elderly, health care workers	0 / 106	0 / 109	NR
Wang X-Y, 2022	Inactivated virus	BBIBP-CorV or CoronaVac	Boost V-01	Placebo	NR	Healthy adults	6 / 5108	8 / 5110	0.75 [0.26 - 2.16]
Thuluva S, 2023 a	Non replicating viral vector	ChAdOx1	Boost BECOV2	Boost Placebo	6	Adults	0 / 156	0 / 52	NR

r1: Number of events in intervention 1, r2: Number of events in intervention 2, N1: Number of patients analyzed in intervention 1; N2: Number of patients analyzed in intervention 2.

All-cause mortality

Reference	Type of prime vaccination	Prime schedule	Intervention 1	Intervention 2	Follow up months	Participants	r1/N1	r2/N2	RR [95% CI]	Risk of bias
										A	B	C	D	E	Overall
Zhang Y, 2023	Inactivated virus	CoronaVac	Boost ChAdTS-S	Placebo	3	Adults	0 / 48	0 / 47	NR
Zhang Y, 2023	Inactivated virus	CoronaVac	Boost RQ3013	Placebo	3	Adults	0 / 47	0 / 47	NR
Zhang Y, 2023	Inactivated virus	CoronaVac	Boost ZR202-CoV	Placebo	3	Adults	0 / 47	0 / 47	NR
Zhang Y, 2023	Inactivated virus	CoronaVac	Boost CoronaVac	Placebo	3	Adults	0 / 46	0 / 47	NR
Hannawi S, 2022	Inactivated virus	BBIBP-CorV	Boost SCTV01C 20mcg	Placebo	1	Adults	0 / 79	0 / 75	NR
Hannawi S, 2022	Inactivated virus	BBIBP-CorV	Boost SCTV01C 40mcg	Placebo	1	Adults	0 / 80	0 / 75	NR
Vadrevu KM, 2022	Inactivated virus	BBV152	Boost BBV152	Placebo	1	Adolescents and adults	0 / 80	0 / 87	NR
Sung J, 2022	Any COVID-19 vaccine	2 doses BNT162b2 or BBIBP	Boost Recombinant inactiv Bacillus subtilis spores	Boost active adjuvant	1.2	Healthy adults	0 / 9	0 / 7	NR
Toledo-Romani ME, 2022 b	Protein subunit	FINLAY-FR-2-25 mcg	Boost FINLAY-FR-1-50 mcg	Placebo	5.4	Adults	11 / 13883	24 / 14303	0.47 [0.23 - 0.96]
Moreira E D, 2022	RNA based vaccine	BNT162b2	Boost BNT162b2	Placebo	2.5	Adults and adolescents	0 / 5055	1 / 5020	0.33 [0.01 - 8.12]
Wang X-Y, 2022	Inactivated virus	BBIBP-CorV or CoronaVac	Boost V-01	Placebo	2	Healthy adults	0 / 5108	0 / 5110	NR
Thuluva S, 2023 a	Non replicating viral vector	ChAdOx1	Boost BECOV2	Boost Placebo	6	Adults	0 / 156	0 / 52	NR

r1: Number of events in intervention 1, r2: Number of events in intervention 2, N1: Number of patients analyzed in intervention 1; N2: Number of patients analyzed in intervention 2.

1st booster VS 1st booster (tables)

Immunogenicity
Geometric mean titre specific antibodies (D14)

Reference	Type of prime vaccination	Prime schedule	Intervention 1	Intervention 2	Follow up days	Participants	GMT1(N1)	GMT2(N2)	GMR [95% CI]	Evaluated by	Risk of bias
											A	B	C	D	E	Overall
Anderson E, 2022	RNA based vaccine	mRNA-1273	Boost 50 mcg mRNA-1273.351	Boost 25 mcg mRNA-1273.351 and 25 mcg mRNA-1273	14	Healthy volunteers	9,591 (25)	9,046 (22)	1.06 [0.78, 1.43]	4-plex Mesoscale Discovery (MSD) 10-plex assay.
Anderson E, 2022	RNA based vaccine	mRNA-1273	Boost 100 mcg mRNA-1273	Boost 25 mcg mRNA-1273.351 and 25 mcg mRNA-1273	14	Healthy volunteers	8,396 (41)	9,046 (22)	0.93 [0.69, 1.24]	4-plex Mesoscale Discovery (MSD) 10-plex assay.
Lien C, 2022 a	Protein subunit	MVC-COV1901	Boost MVC-COV1901-Beta 15 mcg	Boost MVC-COV1901	14	Adults including healthy or stable co-morbidities	32,938 (12)	25,879 (14)	1.27 [0.70, 2.83]	ELISA
Lien C, 2022 a	Protein subunit	MVC-COV1901	Boost MVC-COV1901-Beta 25 mcg	Boost MVC-COV1901	14	Adults including healthy or stable co-morbidities	43,209 (12)	25,879 (14)	1.66 [0.92, 3]	ELISA
Fadlyana E, 2023	Inactivated virus	CoronaVac	boost BNT162b2	boost CoronaVac	28	Healthy adults	18,289 (192)	1,324 (190)	13.81 [11.54, 16.54]	Chemiluminescent microparticle immunoassay (CMIA)
Fadlyana E, 2023	Inactivated virus	CoronaVac	boost BNT162b2	boost BNT162b2	28	Healthy adults	18,289 (192)	18,289 (192)	13.81 [11.54, 16.54]	Chemiluminescent microparticle immunoassay (CMIA)
Fadlyana E, 2023	Inactivated virus	CoronaVac	boost BNT162b2 (half dose)	boost CoronaVac	28	Healthy adults	14,455 (185)	1,324 (190)	10.92 [9.00, 13.24]	Chemiluminescent microparticle immunoassay (CMIA)
Fadlyana E, 2023	Inactivated virus	CoronaVac	boost ChAdOx1 (half dose)	boost CoronaVac	28	Healthy adults	7,267 (191)	1,324 (190)	5.49 [4.56, 6.11]	Chemiluminescent microparticle immunoassay (CMIA)
Launay O, 2022	RNA based vaccine	BNT162b2	Boost MV B1.351	Boost BNT162b2	15	Adults including healthy or stable co-morbidities	2,241 (71)	2,405 (76)	0.93 [0.77, 1.13]	ELISA
Launay O, 2022	RNA based vaccine	BNT162b2	Boost MV D614	Boost BNT162b2	15	Adults including healthy or stable co-morbidities	1,875 (76)	2,405 (76)	0.78 [0.65, 0.94]	ELISA
Li J, 2022	Inactivated virus	CoronaVac	Boost Ad5-vectored	Boost Coronavac	14	Healthy adults	3,090 (96)	369 (102)	8.37 [6.52, 10.75]	ELISA
Costa Clemens SA, 2022	Inactivated virus	CoronaVac	Boost BNT162b2	Boost CoronaVac	28	Healthy adults	674,267 (333)	48,405 (281)	13.4 [11.6, 15.3]	multiplex immunoassay
Costa Clemens SA, 2022	Inactivated virus	CoronaVac	Boost ChAdOx1	Boost CoronaVac	28	Healthy adults	335,213 (296)	48,405 (281)	7.0 [6.1, 8.1]	multiplex immunoassay
Costa Clemens SA, 2022	Inactivated virus	CoronaVac	Boost AD26.COV2-S	Boost CoronaVac	28	Healthy adults	336,851 (294)	48,405 (281)	6.7 [5.8, 7.7]	multiplex immunoassay
Cao Y, 2021	Inactivated virus	CoronaVac	Boost ZF2001	Boost CoronaVac	14	Healthcare workers	10,417 (81)	7,496 (40)	*1.38 [, ]*	ELISA
Nanthapisal S, 2022	Inactivated virus	2 doses of CoronaVac 21-28 days apart	Boost ChAdOx1-S standard dose	Boost ChAdOx1-S low-dose	14	Healthy adults	1,975 (209)	1,664 (209)	1.19 [1.07, 1.31]	ELISA
Shinkai M, 2022	RNA based vaccine	BNT162b2	Boost S-268019-b	Boost BNT162b2	28	Adults	48,465 (101)	55,215 (101)	0.87 [0.72, 1.06]	ELISA
Jin L, 2022	Inactivated virus	CoronaVac	Boost Ad5-vectored high dose	Boost CoronaVac	14	Healthy adults	6,175 (140)	670 (140)	9.21 [6.87, 12.35]	ELISA
Jin L, 2022	Inactivated virus	CoronaVac	Boost Ad5-vectored low dose	Boost CoronaVac	14	Healthy adults	4,625 (140)	670 (140)	6.9 [5.01, 9.50]	ELISA
Chuang C-H, 2022	Non replicating viral vector	ChAdOx1	Boost BNT162b2	Boost MVC-COV1901	28	Healthcare workers	524 (83)	219 (85)	2.39 [1.99, 2.86]	ELISA
Chuang C-H, 2022	Non replicating viral vector	ChAdOx1	Boost mRNA-1273 (half dose)	Boost MVC-COV1901	28	Healthcare workers	657 (85)	219 (85)	3 [2.52, 3.57]	ELISA
Chuang C-H, 2022	Non replicating viral vector	ChAdOx1	Boost mRNA-1273	Boost MVC-COV1901	28	Healthcare workers	709 (85)	219 (85)	3.23 [2.72, 3.85]	ELISA
Sablerolles R, 2022	Non replicating viral vector	Ad26.COV2.S	Boost m-RNA-1273	Boost Ad26.COV2.S	28	Healthcare workers	4,379 (112)	403 (106)	10.86 [8.22, 14.34]	Liaison SARS CoV-2 TrimericS IgG
Sablerolles R, 2022	Non replicating viral vector	Ad26.COV2.S	Boost BNT162b2	Boost Ad26.COV2.S	28	Healthcare workers	2,671 (111)	403 (106)	6.62 [4.93, 8.89]	Liaison SARS CoV-2 TrimericS IgG
Estephan L, 2023 a	Protein subunit	MVC-COV1901	Boost 1/2 MVC-COV1901	Boost MVC-COV1901	28	Adults	17,526 (75)	29,269 (75)	0.60 [0.46, 0.78]	ELISA
Estephan L, 2023 a	Protein subunit	MVC-COV1901	Boost 1/2 mRNA-1273	Boost MVC-COV1901	28	Adults	85,648 (75)	29,269 (75)	2.93 [2.23, 3.83]	ELISA
Estephan L, 2023 a	Protein subunit	MVC-COV1901	Boost ChAdOx1	Boost MVC-COV1901	28	Adults	54,372 (77)	29,269 (75)	1.86 [1.42, 2.43]	ELISA
Estephan L, 2023 c	RNA based vaccine	mRNA-1273	Boost MVC-COV1901	Boost 1/2 mRNA-1273	28	Adults	17,944 (33)	65,881 (44)	0.27 [0.21, 0.36]	ELISA
Estephan L, 2023 c	RNA based vaccine	mRNA-1273	Boost ChAdOx1	Boost 1/2 mRNA-1273	28	Adults	36,618 (41)	65,881 (44)	0.55 [0.43, 0.72]	ELISA
Estephan L, 2023 c	RNA based vaccine	mRNA-1273	Boost 1/2 MVC-COV1901	Boost 1/2 mRNA-1273	28	Adults	18,678 (41)	65,881 (44)	0.28 [0.22, 0.37]	ELISA
Estephan L, 2023 b	Non replicating viral vector	ChadOx1	Boost MVC-COV1901	Boost ChadOx1	28	Adults	11,469 (75)	4,924 (79)	2.33 [1.84, 2.95]	ELISA
Estephan L, 2023 b	Non replicating viral vector	ChadOx1	Boost mRNA-1273 (half dose)	Boost ChadOx1	28	Adults	55,310 (75)	4,924 (79)	11.23 [8.86, 14.24]	ELISA

Geometric mean titre specific antibodies (≥D90)

Reference	Type of prime vaccination	Prime schedule	Intervention 1	Intervention 2	Follow up days	Participants	GMT1(N1)	GMT2(N2)	GMR [95% CI]	Evaluated by	Risk of bias
											A	B	C	D	E	Overall
Jin L, 2022	Inactivated virus	CoronaVac	Boost Ad5-vectored high dose	Boost CoronaVac	365	Healthy adults	1,452 (40)	73 (40)	19.96 [16.29, 25.71]	ELISA
Jin L, 2022	Inactivated virus	CoronaVac	Boost Ad5-vectored low dose	Boost CoronaVac	365	Healthy adults	1,806 (40)	73 (40)	24.81 [20.24, 32.05]	ELISA
Sablerolles R, 2022	Non replicating viral vector	Ad26.COV2.S	Boost m-RNA-1273	Boost Ad26.COV2.S	150	Healthcare workers	746 (93)	123 (85)	6.07 [4.52, 8.13]	Liaison SARS CoV-2 TrimericS IgG
Sablerolles R, 2022	Non replicating viral vector	Ad26.COV2.S	Boost BNT162b2	Boost Ad26.COV2.S	150	Healthcare workers	544 (101)	123 (85)	4.42 [3.31, 5.92]	Liaison SARS CoV-2 TrimericS IgG

Geometric mean titre neutralization assay against wild type (D14)

Reference	Type of prime vaccination	Prime schedule	Intervention 1	Intervention 2	Follow up days	Participants	GMT1(N1)	GMT2(N2)	GMR [95% CI]	Evaluated by	Risk of bias
											A	B	C	D	E	Overall
Anderson E, 2022	RNA based vaccine	mRNA-1273	Boost 50 mcg mRNA-1273.351	Boost 25 mcg mRNA-1273.351 and 25 mcg mRNA-1273	15	Healthy volunteers	2,111 (25)	2,435 (22)	0.87 [0.60, 1.24]	Neutralization assay (PsVN)
Anderson E, 2022	RNA based vaccine	mRNA-1273	Boost 100 mcg mRNA-1273	Boost 25 mcg mRNA-1273.351 and 25 mcg mRNA-1273	15	Healthy volunteers	2,842 (41)	2,435 (22)	1.17 [0.84, 1.62]	Neutralization assay (PsVN)
Al Kaabi N, 2022 b	Inactivated virus	BBIBP-CorV	Boost NVSI-06-08 4-6 months	Boost BBIBP-CorV 4-6 months	15	Healthy adults	3,142 (285)	197 (289)	15.96 [13.34, 19.08]	Live-virus neutralization assay
Al Kaabi N, 2022 b	Inactivated virus	BBIBP-CorV	Boost NVSI-06-08 7-9 months	Boost BBIBP-CorV 7-9 months	15	Healthy adults	4,908 (270)	505 (270)	9.72 [8.04, 11.77]	Live-virus neutralization assay
Al Kaabi N, 2022 b	Inactivated virus	BBIBP-CorV	Boost NVSI-06-08 >9 months	Boost BBIBP-CorV >9 months	15	Healthy adults	4,185 (286)	375 (278)	11.17 [9.44, 13.22]	Live-virus neutralization assay
Lien C, 2022 a	Protein subunit	MVC-COV1901	Boost MVC-COV1901-Beta 15 mcg	Boost MVC-COV1901	28	Adults including healthy or stable co-morbidities	1,805 (12)	1,352 (14)	1.33 [0.61, 2.89]	Plaque reduction neutralization test
Lien C, 2022 a	Protein subunit	MVC-COV1901	Boost MVC-COV1901-Beta 25 mcg	Boost MVC-COV1901	28	Adults including healthy or stable co-morbidities	3,603 (12)	1,352 (14)	2.64 [1.22, 5.79]	Plaque reduction neutralization test
Amplify, 2023 b	RNA based vaccine	BNT162b2	Boost Ad26.COV2.S 1*10^10 vp	Boost Ad26.COV2.S 5*10^10 vp	14	Adults including elderly and stable co-morbidities	3,218 (88)	4,439 (299)	0.725 [0.570, 0.922]	Virus neutralization assay (VNA)
Amplify, 2023 b	RNA based vaccine	BNT162b2	Boost Ad26.COV2.S 2.5*10^10 vp	Boost Ad26.COV2.S 5*10^10 vp	14	Adults including elderly and stable co-morbidities	3,566 (295)	4,439 (299)	0.803 [0.696, 0.927]	Virus neutralization assay (VNA)
Amplify, 2023 a	Non replicating viral vector	Ad26.COV2.S	Boost Ad26.COV2.S 1*10^10 vp	Boost Ad26.COV2.S 5*10^10 vp	14	Adults including elderly and stable co-morbidities	734 (93)	1,130 (298)	0.649 [0.484, 0.827]	Virus neutralization assay (VNA)
Amplify, 2023 a	Non replicating viral vector	Ad26.COV2.S	Boost Ad26.COV2.S 2.5*10^10 vp	Boost Ad26.COV2.S 5*10^10 vp	14	Adults including elderly and stable co-morbidities	915 (297)	1,130 (298)	0.810 [0.665, 0.986]	Virus neutralization assay (VNA)
Al Kaabi N, 2023	Inactivated virus	BBIBP-CorV	Boost NVSI-06-09	Boost BBIBP-CorV	14	Healthy adults	2,349 (255)	506 (249)	4.64 [3.93, 5.47]	Live-virus microneutralization assay
Niyomnaitham S, 2022	Inactivated virus	CoronaVac	Boost ChAdOx1 (1/5 dose ID)	Boost BNT162b2 (1/6 dose ID)	14	Healthy adults	206 (45)	288 (45)	0.71 [0.48, 1.07]	Plaque reduction neutralization test
Rao C, 2022	Inactivated virus	CoronaVac	Boost SCB-2019	Boost CoronaVac	14	Adults who are healthy or have a stable pre-existing medical condition	744 (209)	164 (211)	4.63 [3.96, 5.41]	Microneutralization assay
Niyomnaitham S, 2023	Inactivated virus	Coronavac	Boost ChAdOx1	Boost BNT162b2	28	Healthy adults	575 (97)	928 (99)	NR	Micro Neutralizing Antibody Titer
Omma A, 2022	Inactivated virus	CoronaVac	Boost TURKOVAC	Boost CoronaVac	28	Adults	34 (104)	28 (114)	1.45 [0.36, 5.80]	Microneutralization test (MNT)
Launay O, 2022	RNA based vaccine	BNT162b2	Boost MV B1.351	Boost BNT162b2	15	Adults including healthy or stable co-morbidities	1,801 (71)	1,364 (76)	1.32 [0.95, 1.83]	Microneutralization test
Launay O, 2022	RNA based vaccine	BNT162b2	Boost MV D614	Boost BNT162b2	15	Adults including healthy or stable co-morbidities	1,168 (76)	1,364 (76)	0.86 [0.62, 1.18]	Microneutralization test
Li J, 2022	Inactivated virus	CoronaVac	Boost Ad5-vectored	Boost Coronavac	14	Healthy adults	197 (96)	34 (102)	5.9 [4.5, 7.7]	Cytopathic effect-based microneutralization assay- wild-type SARS-CoV-2
Cao Y, 2021	Inactivated virus	CoronaVac	Boost ZF2001	Boost CoronaVac	14	Healthcare workers	1,306 (81)	794 (40)	1.64 [1.09, 2.46]	CPE
Nanthapisal S, 2022	Inactivated virus	2 doses of CoronaVac 21-28 days apart	Boost ChAdOx1-S standard dose	Boost ChAdOx1-S low-dose	14	Healthy adults	96 (207)	97 (203)	0.99 [0.97, 1.01]	Virus neutralization test (sVNT)
Shinkai M, 2022	RNA based vaccine	BNT162b2	Boost S-268019-b	Boost BNT162b2	14	Adults	128 (101)	139 (101)	0.94 [0.76, 1.09]	Cytopathic effect-based virus neutralization test
Mok C K P, 2022	Inactivated virus	CoronaVac	Boost CoronaVac	Boost BNT162b2	30	Adults	17 (40)	207 (40)	NR	PRNT90
Toledo-Romani ME, 2022 a	Protein subunit	FINLAY-FR-2-25 mcg	Boost FR-1	Boost FINLAY-FR-2	28	Healthy adults	43 (55)	33 (51)	1.29 [0.81, 2.06]	Conventional virus neutralization test
Assantachai P, 2023	Non replicating viral vector	ChAdOx1	Boost mRNA-1273 20 mcg ID	Boost mRNA-1273	14-28	Adults	1,212 (35)	1,718 (35)	0.70 [0.40, 1.23]	Pseudovirus neutralization test assay
Assantachai P, 2023	Non replicating viral vector	ChAdOx1	Boost BNT162b2 10 mcg ID	Boost BNT162b2	14-28	Adults	587 (68)	713 (68)	0.82 [0.51, 1.31]	Pseudovirus neutralization test assay
Corominas J, 2023	RNA based vaccine	BNT162b2	Boost PHH-1V	Boost BNT162b2	14	Healthy adults	1,966 (500)	3,309 (241)	0.59 [0.51, 0.69]	PNA
Jin L, 2022	Inactivated virus	CoronaVac	Boost Ad5-vectored high dose	Boost CoronaVac	28	Healthy adults	1,635 (40)	70 (40)	23.42 [19.05, 30.40]	CPE-based microneutralisation
Jin L, 2022	Inactivated virus	CoronaVac	Boost Ad5-vectored low dose	Boost CoronaVac	28	Healthy adults	1,911 (40)	70 (40)	27.40 [22.27, 35.39]	CPE-based microneutralisation
Wang L, 2022	Inactivated virus	CoronaVac	Boost CoronaVac 1.5 10m	Boost CoronaVax 1.5 12m	28	Children and adolescents	598 (85)	462 (85)	1.29 [0.89, 1.86]	Micro cytopathic effect assay
Wang L, 2022	Inactivated virus	CoronaVac	Boost CoronaVax 3 10m	Boost CoronaVax 3 12m	28	Children and adolescents	681 (85)	754 (82)	0.91 [0.64, 1.28]	Micro cytopathic effect assay
Sablerolles R, 2022	Non replicating viral vector	Ad26.COV2.S	Boost m-RNA-1273	Boost Ad26.COV2.S	28	Healthcare workers	5,686 (11)	614 (12)	9.26 [5.20, 16.48]	PRNT
Sablerolles R, 2022	Non replicating viral vector	Ad26.COV2.S	Boost BNT162b2	Boost Ad26.COV2.S	28	Healthcare workers	2,204 (12)	614 (12)	3.58 [1.11, 11.59]	PRNT
Estephan L, 2023 a	Protein subunit	MVC-COV1901	Boost 1/2 MVC-COV1901	Boost MVC-COV1901	28	Adults	985 (75)	1,690 (75)	0.58 [0.43, 0.79]	Live virus neutralization assay
Estephan L, 2023 a	Protein subunit	MVC-COV1901	Boost 1/2 mRNA-1273	Boost MVC-COV1901	28	Adults	5,934 (75)	1,690 (75)	3.51 [2.59, 4.76]	Live virus neutralization assay
Estephan L, 2023 a	Protein subunit	MVC-COV1901	Boost ChAdOx1	Boost MVC-COV1901	28	Adults	3,835 (77)	1,690 (75)	2.27 [1.67, 3.07]	Live virus neutralization assay
Estephan L, 2023 c	RNA based vaccine	mRNA-1273	Boost MVC-COV1901	Boost 1/2 mRNA-1273	28	Adults	735 (33)	2,635 (44)	0.28 [0.19, 0.40]	Live virus neutralization assay
Estephan L, 2023 c	RNA based vaccine	mRNA-1273	Boost ChAdOx1	Boost 1/2 mRNA-1273	28	Adults	1,632 (41)	2,635 (44)	0.62 [0.44, 0.87]	Live virus neutralization assay
Estephan L, 2023 c	RNA based vaccine	mRNA-1273	Boost 1/2 MVC-COV1901	Boost 1/2 mRNA-1273	28	Adults	577 (41)	2,635 (44)	0.22 [0.16, 0.31]	Live virus neutralization assay
Estephan L, 2023 b	Non replicating viral vector	ChadOx1	Boost MVC-COV1901	Boost ChadOx1	28	Adults	673 (75)	232 (79)	2.90 [2.22, 3.80]	Live virus neutralization assay
Estephan L, 2023 b	Non replicating viral vector	ChadOx1	Boost mRNA-1273 (half dose)	Boost ChadOx1	28	Adults	3,121 (75)	232 (79)	13.48 [10.30, 17.62]	Live virus neutralization assay
Leung N, 2022	RNA based vaccine	BNT162b2	Boost CoronaVac	Boost BNT162b2	28	Adults including co-morbidities	92 (20)	816 (20)	NR	Live virus plaque reduction neutralization test PRNT50
Leung N, 2022	Inactivated virus	CoronaVac	Boost BNT162b2	Boost CoronaVac	28	Adults including co-morbidities	905 (20)	109 (20)	NR	Live virus plaque reduction neutralization test PRNT50
Jin P, 2023 a	Inactivated virus	CoronaVac	Boost Ad5-vectored 5×10^10 vp	Boost CoronaVac	14	Elderly	286 (50)	48 (50)	5.94 [4.61, 7.65]	Microneutralization assay
Kulkarni P, 2023 a	Non replicating viral vector	ChAdOx1	Boost SII-NVX-CoV2373	Boost ChAdOx1	29	Adults	3,963 (92)	2,032 (93)	1.95 [1.52, 2.50]	Microneutralization assay (MN)
Kulkarni P , 2023 b	Inactivated virus	BBV152	Boost SII-NVX-CoV2373	Boost BBV152	29	Adults	2,848 (91)	516 (93)	5.5 [4, 7.8]	Microneutralization assay (MN)

Geometric mean titre neutralization assay against wild type (≥D90)

Reference	Type of prime vaccination	Prime schedule	Intervention 1	Intervention 2	Follow up days	Participants	GMT1(N1)	GMT2(N2)	GMR [95% CI]	Evaluated by	Risk of bias
											A	B	C	D	E	Overall
Niyomnaitham S, 2023	Inactivated virus	Coronavac	Boost ChAdOx1	Boost BNT162b2	90	Healthy adults	309 (97)	363 (99)	NR	Micro Neutralizing Antibody Titer
Corominas J, 2023	RNA based vaccine	BNT162b2	Boost PHH-1V	Boost BNT162b2	98	Healthy adults	1,120 (78)	960 (42)	1.16 [0.82, 1.66]	PNA
Jin L, 2022	Inactivated virus	CoronaVac	Boost Ad5-vectored high dose	Boost CoronaVac	365	Healthy adults	171 (40)	8 (40)	21.41 [12.77, 66.23]	CPE-based microneutralisation
Jin L, 2022	Inactivated virus	CoronaVac	Boost Ad5-vectored low dose	Boost CoronaVac	365	Healthy adults	204 (40)	8 (40)	25.58 [79.37, 15.22]	CPE-based microneutralisation
Sablerolles R, 2022	Non replicating viral vector	Ad26.COV2.S	Boost m-RNA-1273	Boost Ad26.COV2.S	150	Healthcare workers	822 (11)	293 (12)	2.80 [1.15, 6.83]	PRNT
Sablerolles R, 2022	Non replicating viral vector	Ad26.COV2.S	Boost BNT162b2	Boost Ad26.COV2.S	150	Healthcare workers	748 (12)	293 (12)	2.55 [1.27, 5.11]	PRNT

Geometric mean titre neutralization assay against Omicron variant (D14)

Reference	Type of prime vaccination	Prime schedule	Intervention 1	Intervention 2	Follow up days	Participants	GMT1(N1)	GMT2(N2)	GMR [95% CI]	Evaluated by	Risk of bias
											A	B	C	D	E	Overall
Al Kaabi N, 2022 b	Inactivated virus	BBIBP-CorV	Boost NVSI-06-08 7-9 months	Boost BBIBP-CorV 7-9 months	15	Healthy adults	368 (270)	45 (270)	8.17 [6.03, 11.06]	Live-virus neutralization assay
Lien C, 2022 a	Protein subunit	MVC-COV1901	Boost MVC-COV1901-Beta 15 mcg	Boost MVC-COV1901	28	Adults including healthy or stable co-morbidities	240 (12)	139 (14)	1.72 [0.76, 3.91]	Pseudovirus neutralisation assay.
Lien C, 2022 a	Protein subunit	MVC-COV1901	Boost MVC-COV1901-Beta 25 mcg	Boost MVC-COV1901	28	Adults including healthy or stable co-morbidities	426 (12)	139 (14)	3.05 [1.44, 6.47]	Pseudovirus neutralisation assay.
Al Kaabi N, 2023	Inactivated virus	BBIBP-CorV	Boost NVSI-06-09	Boost BBIBP-CorV	14	Healthy adults	1,714 (255)	143 (249)	11.96 [9.60, 14.90]	Live-virus neutralizing antibody response against Omicron (BA.1.1) variant (PPS)
Niyomnaitham S, 2022	Inactivated virus	CoronaVac	Boost ChAdOx1 (1/5 dose ID)	Boost BNT162b2 (1/6 dose ID)	14	Healthy adults	46 (45)	53 (45)	0.87 [0.55, 1.38]	Plaque reduction neutralization test (PRNT50)
Rao C, 2022	Inactivated virus	CoronaVac	Boost SCB-2019	Boost CoronaVac	14	Adults who are healthy or have a stable pre-existing medical condition	253 (209)	73 (211)	3.45 [2.70, 4.42]	Microneutralization assay
Niyomnaitham S, 2023	Inactivated virus	Coronavac	Boost ChAdOx1	Boost BNT162b2	28	Healthy adults	119 (97)	256 (99)	0.46 [0.36, 0.59]	Pseudovirus Neutralizing Antibody Titers (PVNT50)
Launay O, 2022	RNA based vaccine	BNT162b2	Boost MV B1.351	Boost BNT162b2	15	Adults including healthy or stable co-morbidities	253 (71)	140 (76)	1.81 [1.34, 2.44]	Microneutralization test
Launay O, 2022	RNA based vaccine	BNT162b2	Boost MV D614	Boost BNT162b2	15	Adults including healthy or stable co-morbidities	124 (76)	140 (76)	0.88 [0.67, 1.17]	Microneutralization test
Costa Clemens SA, 2022	Inactivated virus	CoronaVac	Boost BNT162b2	Boost CoronaVac	28	Healthy adults	223 (20)	17 (20)	13.12 [5.66, 30.40]	Live-virus neutralization assay against Omicron
Costa Clemens SA, 2022	Inactivated virus	CoronaVac	Boost ChAdOx1	Boost CoronaVac	28	Healthy adults	102 (20)	17 (20)	6 [2.91, 12.36]	Live-virus neutralization assay against Omicron
Costa Clemens SA, 2022	Inactivated virus	CoronaVac	Boost AD26.COV2-S	Boost CoronaVac	28	Healthy adults	138 (20)	17 (20)	8.12 [3.72, 17.69]	Live-virus neutralization assay against Omicron
Assantachai P, 2023	Non replicating viral vector	ChAdOx1	Boost mRNA-1273 20 mcg ID	Boost mRNA-1273	14-28	Adults	318 (35)	617 (35)	0.51 [0.29, 0.92]	Pseudovirus neutralization test assay
Assantachai P, 2023	Non replicating viral vector	ChAdOx1	Boost BNT162b2 10 mcg ID	Boost BNT162b2	14-28	Adults	148 (68)	230 (68)	0.64 [0.42, 0.98]	Pseudovirus neutralization test assay
Corominas J, 2023	RNA based vaccine	BNT162b2	Boost PHH-1V	Boost BNT162b2	14	Healthy adults	2,036 (500)	1,211 (241)	1.70 [1.41, 2]	Pseudovirion-based neutralisation assay (PBNA)
Jin L, 2022	Inactivated virus	CoronaVac	Boost Ad5-vectored high dose	Boost CoronaVac	28	Healthy adults	23 (40)	4 (40)	5.67 [3.01, 47.85]	Cyto-pathic effect-based microneutralization assay
Jin L, 2022	Inactivated virus	CoronaVac	Boost Ad5-vectored low dose	Boost CoronaVac	28	Healthy adults	52 (40)	4 (40)	12.77 [6.61, 188.68]	Cyto-pathic effect-based microneutralization assay
Wang L, 2022	Inactivated virus	CoronaVac	Boost CoronaVac 1.5 10m	Boost CoronaVax 1.5 12m	28	Children and adolescents	24 (85)	24 (85)	0.93 [0.65, 1.47]	micro cytopathogenic effect assay
Wang L, 2022	Inactivated virus	CoronaVac	Boost CoronaVax 3 10m	Boost CoronaVax 3 12m	28	Children and adolescents	35 (85)	40 (82)	0.86 [0.60, 1.23]	micro cytopathogenic effect assay
Chuang C-H, 2022	Non replicating viral vector	ChAdOx1	Boost BNT162b2	Boost MVC-COV1901	28	Healthcare workers	146 (30)	37 (30)	NR	Live virus neutralization
Chuang C-H, 2022	Non replicating viral vector	ChAdOx1	Boost mRNA-1273 (half dose)	Boost MVC-COV1901	28	Healthcare workers	204 (30)	37 (30)	5.51 [3.42, 8.90]	Live virus neutralization
Chuang C-H, 2022	Non replicating viral vector	ChAdOx1	Boost mRNA-1273	Boost MVC-COV1901	28	Healthcare workers	250 (30)	37 (30)	6.75 [4.30, 10.61]	Live virus neutralization
Estephan L, 2023 a	Protein subunit	MVC-COV1901	Boost 1/2 MVC-COV1901	Boost MVC-COV1901	28	Adults	195 (75)	247 (75)	NR	Pseudovirus neutralizing assay
Estephan L, 2023 a	Protein subunit	MVC-COV1901	Boost 1/2 mRNA-1273	Boost MVC-COV1901	28	Adults	955 (75)	247 (75)	NR	Pseudovirus neutralizing assay
Estephan L, 2023 a	Protein subunit	MVC-COV1901	Boost ChAdOx1	Boost MVC-COV1901	28	Adults	661 (77)	247 (75)	NR	Pseudovirus neutralizing assay
Estephan L, 2023 c	RNA based vaccine	mRNA-1273	Boost MVC-COV1901	Boost 1/2 mRNA-1273	28	Adults	105 (33)	658 (44)	NR	Pseudovirus neutralizing assay
Estephan L, 2023 c	RNA based vaccine	mRNA-1273	Boost ChAdOx1	Boost 1/2 mRNA-1273	28	Adults	657 (41)	658 (44)	NR	Pseudovirus neutralizing assay
Estephan L, 2023 c	RNA based vaccine	mRNA-1273	Boost 1/2 MVC-COV1901	Boost 1/2 mRNA-1273	28	Adults	68 (41)	658 (44)	NR	Pseudovirus neutralizing assay
Estephan L, 2023 b	Non replicating viral vector	ChadOx1	Boost MVC-COV1901	Boost ChadOx1	28	Adults	63 (75)	27 (79)	NR	Pseudovirus neutralizing assay
Estephan L, 2023 b	Non replicating viral vector	ChadOx1	Boost mRNA-1273 (half dose)	Boost ChadOx1	28	Adults	651 (75)	27 (79)	NR	Pseudovirus neutralizing assay
Leung N, 2022	RNA based vaccine	BNT162b2	Boost CoronaVac	Boost BNT162b2	28	Adults including co-morbidities	6 (20)	67 (20)	NR	Live virus plaque reduction neutralization test PRNT50
Leung N, 2022	Inactivated virus	CoronaVac	Boost BNT162b2	Boost CoronaVac	28	Adults including co-morbidities	80 (20)	6 (20)	NR	Live virus plaque reduction neutralization test PRNT50
Jin P, 2023 a	Inactivated virus	CoronaVac	Boost Ad5-vectored 5×10^10 vp	Boost CoronaVac	14	Elderly	33 (50)	4 (50)	7.5 [4.7, 11.9]	Microneutralization assay
Kulkarni P, 2023 a	Non replicating viral vector	ChAdOx1	Boost SII-NVX-CoV2373	Boost ChAdOx1	29	Adults	165 (92)	87 (93)	1.89 [1.04, 3.45]	Microneutralization assay (MN)
Kulkarni P , 2023 b	Inactivated virus	BBV152	Boost SII-NVX-CoV2373	Boost BBV152	29	Adults	194 (91)	41 (93)	4.72 [2.54, 8.77]	Microneutralization assay (MN)
Li X, 2023	Inactivated virus	Any inactivated COVID-19 vaccine	Boost aerosolized Ad5-nCoV	Boost CoronaVac		Healthy volunteers	91 (*)	19 (*)	4.78 [3.84, 5.96]	Pseudovirus neutralization test

Geometric mean titre neutralization assay against Omicron variant (≥D90)

Reference	Type of prime vaccination	Prime schedule	Intervention 1	Intervention 2	Follow up days	Participants	GMT1(N1)	GMT2(N2)	GMR [95% CI]	Evaluated by
	A	B	C	D	E	Overall
Corominas J, 2023	RNA based vaccine	BNT162b2	Boost PHH-1V	Boost BNT162b2	98	Healthy adults	618 (78)	349 (42)	1.75 [1.22, 2.56]	Pseudovirion-based neutralisation assay (PBNA)
Jin L, 2022	Inactivated virus	CoronaVac	Boost Ad5-vectored high dose	Boost CoronaVac	180	Healthy adults	12 (40)	4 (40)	2.95 [1.65, 14.01]	Cyto-pathic effect-based microneutralization assay
Jin L, 2022	Inactivated virus	CoronaVac	Boost Ad5-vectored low dose	Boost CoronaVac	180	Healthy adults	16 (40)	4 (40)	3.93 [2.14, 24.39]	Cyto-pathic effect-based microneutralization assay

Safety
Serious adverse events

Reference	Type of prime vaccination	Prime schedule	Intervention 1	Intervention 2	Follow up months	Participants	r1/N1	r2/N2	RR [95% CI]	Risk of bias
										A	B	C	D	E	Overall
Anderson E, 2022	RNA based vaccine	mRNA-1273	Boost 50 mcg mRNA-1273.351	Boost 25 mcg mRNA-1273.351 and 25 mcg mRNA-1273	1	Healthy volunteers	0 / 25	1 / 23	0.31 [0.01 - 7.16]
Anderson E, 2022	RNA based vaccine	mRNA-1273	Boost 100 mcg mRNA-1273	Boost 25 mcg mRNA-1273.351 and 25 mcg mRNA-1273	1	Healthy volunteers	0 / 48	1 / 23	0.16 [0.01 - 3.81]
Lien C, 2022 a	Protein subunit	MVC-COV1901	Boost MVC-COV1901-Beta 15 mcg	Boost MVC-COV1901	0.9	Adults including healthy or stable co-morbidities	0 / 15	0 / 15	NR
Lien C, 2022 a	Protein subunit	MVC-COV1901	Boost MVC-COV1901-Beta 25 mcg	Boost MVC-COV1901	0.9	Adults including healthy or stable co-morbidities	0 / 15	0 / 15	NR
Amplify, 2023 b	RNA based vaccine	BNT162b2	Boost Ad26.COV2.S 1*10^10 vp	Boost Ad26.COV2.S 5*10^10 vp	4.5	Adults including elderly and stable co-morbidities	1 / 106	3 / 326	1.03 [0.11 - 9.75]
Amplify, 2023 b	RNA based vaccine	BNT162b2	Boost Ad26.COV2.S 2.5*10^10 vp	Boost Ad26.COV2.S 5*10^10 vp	4.5	Adults including elderly and stable co-morbidities	1 / 326	3 / 326	0.33 [0.03 - 3.19]
Amplify, 2023 a	Non replicating viral vector	Ad26.COV2.S	Boost Ad26.COV2.S 1*10^10 vp	Boost Ad26.COV2.S 5*10^10 vp	4.5	Adults including elderly and stable co-morbidities	0 / 116	1 / 330	0.95 [0.04 - 23.05]
Amplify, 2023 a	Non replicating viral vector	Ad26.COV2.S	Boost Ad26.COV2.S 2.5*10^10 vp	Boost Ad26.COV2.S 5*10^10 vp	4.5	Adults including elderly and stable co-morbidities	3 / 328	1 / 330	3.02 [0.32 - 28.87]
Fadlyana E, 2023	Inactivated virus	CoronaVac	boost BNT162b2	boost CoronaVac	28	Healthy adults	1 / 193	0 / 191	2.97 [0.12 - 72.43]
Fadlyana E, 2023	Inactivated virus	CoronaVac	boost BNT162b2	boost BNT162b2	28	Healthy adults	1 / 193	1 / 193	1 [0.06 - 15.87]
Fadlyana E, 2023	Inactivated virus	CoronaVac	boost BNT162b2 (half dose)	boost CoronaVac	28	Healthy adults	0 / 186	0 / 191	NR
Fadlyana E, 2023	Inactivated virus	CoronaVac	boost ChAdOx1 (half dose)	boost CoronaVac	28	Healthy adults	1 / 192	0 / 191	2.98 [0.12 - 72.8]
Al Kaabi N, 2023	Inactivated virus	BBIBP-CorV	Boost NVSI-06-09	Boost BBIBP-CorV	1	Healthy adults	0 / 260	0 / 256	NR
Rao C, 2022	Inactivated virus	CoronaVac	Boost SCB-2019	Boost CoronaVac	2.0	Adults who are healthy or have a stable pre-existing medical condition	0 / 214	1 / 216	0.34 [0.01 - 8.21]
Niyomnaitham S, 2023	Inactivated virus	Coronavac	Boost ChAdOx1	Boost BNT162b2	3	Healthy adults	0 / 307	0 / 308	NR
Tawinprai K, 2022	Inactivated virus	CoronaVac	Boost ChAdOx1	Boost BBIBP-CorV	0.5	Adults without active underlying disease	0 / 41	0 / 40	NR
Omma A, 2022	Inactivated virus	CoronaVac	Boost TURKOVAC	Boost CoronaVac	1	Adults	0 / 108	1 / 114	0.35 [0.01 - 8.54]
Launay O, 2022	RNA based vaccine	BNT162b2	Boost MV B1.351	Boost BNT162b2	0.5	Adults including healthy or stable co-morbidities	1 / 80	0 / 82	3.07 [0.13 - 74.36]
Launay O, 2022	RNA based vaccine	BNT162b2	Boost MV D614	Boost BNT162b2	0.5	Adults including healthy or stable co-morbidities	1 / 85	0 / 82	2.89 [0.12 - 70.04]
Poh XY, 2022	RNA based vaccine	BNT162b2	Boost mRNA-1273	Boost BNT162b2	28	Adults	0 / 48	0 / 50	NR
Li J, 2022	Inactivated virus	CoronaVac	Boost Ad5-vectored	Boost Coronavac	1	Healthy adults	0 / 96	0 / 102	NR
Reindl-Schwaighofer R, 2021	RNA based vaccine	BNT162b2 or mRNA-1273	Boost BNT162b2 or mRNA-1273	Boost Ad26COVS1	1	Kidney transplant recipients	2 / 99	3 / 99	0.67 [0.11 - 3.9]
Costa Clemens SA, 2022	Inactivated virus	CoronaVac	Boost BNT162b2	Boost CoronaVac	1	Healthy adults	1 / 339	0 / 291	2.58 [0.11 - 62.99]
Costa Clemens SA, 2022	Inactivated virus	CoronaVac	Boost ChAdOx1	Boost CoronaVac	1	Healthy adults	1 / 304	0 / 291	2.87 [0.12 - 70.22]
Costa Clemens SA, 2022	Inactivated virus	CoronaVac	Boost AD26.COV2-S	Boost CoronaVac	1	Healthy adults	3 / 305	0 / 291	6.68 [0.35 - 128.75]
Shinkai M, 2022	RNA based vaccine	BNT162b2	Boost S-268019-b	Boost BNT162b2	NR	Adults	0 / 101	0 / 103	NR
Bruminhent J, 2022	Inactivated virus	2 doses of CoronaVac (3–5 weeks apart) or followed by 1 dose of ChAdOx1 or 2 doses of ChAdOx1	CoronaVac or ChAdOx1/Boost BNT162b2 or mRNA-1273	Boost ChAdOx1	0.2	Kidney transplant recipients	0 / 40	0 / 37	NR
Rose W, 2023	Non replicating viral vector	ChAdOx1	Boost BBV152	Boost ChAdOx1	3	Adults	0 / 99	2 / 101	0.2 [0.01 - 4.2]
Rose W, 2023	Inactivated virus	BBV152	Boost ChAdOx1	Boost BBV152	3	Adults	1 / 102	1 / 102	1 [0.06 - 15.77]
Assantachai P, 2023	Non replicating viral vector	ChAdOx1	Boost mRNA-1273 20 mcg ID	Boost mRNA-1273	3	Adults	0 / 35	0 / 35	NR
Assantachai P, 2023	Non replicating viral vector	ChAdOx1	Boost BNT162b2 10 mcg ID	Boost BNT162b2	3	Adults	0 / 70	0 / 70	NR
Corominas J, 2023	RNA based vaccine	BNT162b2	Boost PHH-1V	Boost BNT162b2	3.2	Healthy adults	1 / 513	0 / 252	1.48 [0.06 - 36.09]
Jin L, 2022	Inactivated virus	CoronaVac	Boost Ad5-vectored high dose	Boost CoronaVac	12	Healthy adults	1 / 137	1 / 137	1 [0.06 - 15.83]
Jin L, 2022	Inactivated virus	CoronaVac	Boost Ad5-vectored low dose	Boost CoronaVac	6	Healthy adults	2 / 139	1 / 137	1.97 [0.18 - 21.49]
Kho M, 2022	RNA based vaccine	mRNA-1273 or BNT162b2	Boost mRNA-1273 (2 doses)	Boost mRNA-1273	0.9	Adult kidney transplant recipients	0 / 75	3 / 71	0.14 [0.01 - 2.57]
Kho M, 2022	RNA based vaccine	mRNA-1273 or BNT162b2	Boost Ad26.COV2-S	Boost mRNA-1273	0.9	Adult kidney transplant recipients	1 / 78	3 / 71	0.3 [0.03 - 2.85]
Wang L, 2022	Inactivated virus	CoronaVac	Boost CoronaVac 1.5 10m	Boost CoronaVax 1.5 12m	1	Children and adolescents	1 / 86	0 / 87	3.03 [0.13 - 73.46]
Wang L, 2022	Inactivated virus	CoronaVac	Boost CoronaVax 3 10m	Boost CoronaVax 3 12m	1	Children and adolescents	0 / 85	0 / 88	NR
Sablerolles R, 2022	Non replicating viral vector	Ad26.COV2.S	Boost m-RNA-1273	Boost Ad26.COV2.S	1	Healthcare workers	0 / 112	0 / 106	NR
Sablerolles R, 2022	Non replicating viral vector	Ad26.COV2.S	Boost BNT162b2	Boost Ad26.COV2.S	1	Healthcare workers	0 / 111	0 / 106	NR
Costa Clemens, 2022	Non replicating viral vector	ChadOx1	Boost 9 mcg SCB-2019 + alum	Boost ChadOx1	0.92	Adults	0 / 30	0 / 29	NR
Costa Clemens, 2022	Non replicating viral vector	ChadOx1	Boost 9 mcg SCB-2019 + CpG + alum	Boost ChadOx1	0.92	Adults	1 / 29	0 / 29	3 [0.13 - 70.59]
Costa Clemens, 2022	Non replicating viral vector	ChadOx1	Boost 30 mcg SCB-2019 + CpG + alum	Boost ChadOx1	0.92	Adults	0 / 32	0 / 29	NR
Natori Y, 2023	RNA based vaccine	BNT162b2	Boost Ad26.COV2.S	Boost BNT162b2	1	Transplant recipients	0 / 28	0 / 30	NR
Jin P, 2023 a	Inactivated virus	CoronaVac	Boost Ad5-vectored 5×10^10 vp	Boost CoronaVac	6	Elderly	1 / 99	0 / 100	3.03 [0.12 - 73.49]
Intapiboon P, 2021	Inactivated virus	CoronaVac	CoronaVac 3mcg D0/14	CoronaVac	1	Healthy adults	0 / 30	0 / 30	NR
Intapiboon P, 2021	Inactivated virus	CoronaVac	CoronaVac 3mcg D0/14	CoronaVac	1	Healthy adults	0 / 31	0 / 30	NR
Akahata W, 2023 a	RNA based vaccine	BNT162b2	Boost VLPCOV-01 0.3 mcg	Boost BNT162b2	6	Healthy volunteers	0 / 10	0 / 10	NR
Akahata W, 2023 a	RNA based vaccine	BNT162b2	Boost VLPCOV-01 1 mcg	Boost BNT162b2	6	Healthy volunteers	0 / 10	0 / 10	NR
Akahata W, 2023 a	RNA based vaccine	BNT162b2	Boost VLPCOV-01 3 mcg	Boost BNT162b2	6	Healthy volunteers	0 / 10	0 / 10	NR
Akahata W , 2023 b	RNA based vaccine	BNT162b2	Boost VLPCOV-01 0.3 mcg	Boost BNT162b2	6	Healthy volunteers	0 / 10	0 / 10	NR
Akahata W , 2023 b	RNA based vaccine	BNT162b2	Boost VLPCOV-01 1 mcg	Boost BNT162b2	6	Healthy volunteers	0 / 10	0 / 10	NR
Akahata W , 2023 b	RNA based vaccine	BNT162b2	Boost VLPCOV-01 3 mcg	Boost BNT162b2	6	Healthy volunteers	0 / 10	0 / 10	NR

r1: Number of events in intervention 1, r2: Number of events in intervention 2, N1: Number of patients analyzed in intervention 1; N2: Number of patients analyzed in intervention 2.

All-cause mortality

Reference	Type of prime vaccination	Prime schedule	Intervention 1	Intervention 2	Follow up months	Participants	r1/N1	r2/N2	RR [95% CI]	Risk of bias
										A	B	C	D	E	Overall
Corominas J, 2023	RNA based vaccine	BNT162b2	Boost PHH-1V	Boost BNT162b2	3.2	Healthy adults	0 / 513	0 / 252	NR
Zhang Y, 2023	Inactivated virus	CoronaVac	Boost ChAdTS-S	Placebo	3	Adults	0 / 48	0 / 47	NR
Zhang Y, 2023	Inactivated virus	CoronaVac	Boost RQ3013	Placebo	3	Adults	0 / 47	0 / 47	NR
Zhang Y, 2023	Inactivated virus	CoronaVac	Boost ZR202-CoV	Placebo	3	Adults	0 / 47	0 / 47	NR
Zhang Y, 2023	Inactivated virus	CoronaVac	Boost CoronaVac	Placebo	3	Adults	0 / 46	0 / 47	NR
Mrak D, 2022	RNA based vaccine	mRNA-1273 or BNT162b2	Boost ChAdOx1	Boost homologous mRNA-1273 or BNT162b2	0.9	Immunosuppressed adults	0 / 22	0 / 24	NR
Al Kaabi N, 2022 b	Inactivated virus	BBIBP-CorV	Boost NVSI-06-08 4-6 months	Boost BBIBP-CorV 4-6 months	1	Healthy adults	0 / 299	0 / 301	NR
Al Kaabi N, 2022 b	Inactivated virus	BBIBP-CorV	Boost NVSI-06-08 7-9 months	Boost BBIBP-CorV 7-9 months	1	Healthy adults	0 / 297	0 / 303	NR
Al Kaabi N, 2022 b	Inactivated virus	BBIBP-CorV	Boost NVSI-06-08 >9 months	Boost BBIBP-CorV >9 months	1	Healthy adults	0 / 300	0 / 300	NR
Lien C, 2022 a	Protein subunit	MVC-COV1901	Boost MVC-COV1901-Beta 15 mcg	Boost MVC-COV1901	0.9	Adults including healthy or stable co-morbidities	0 / 15	0 / 15	NR
Lien C, 2022 a	Protein subunit	MVC-COV1901	Boost MVC-COV1901-Beta 25 mcg	Boost MVC-COV1901	0.9	Adults including healthy or stable co-morbidities	0 / 15	0 / 15	NR
Amplify, 2023 a	Non replicating viral vector	Ad26.COV2.S	Boost Ad26.COV2.S 1*10^10 vp	Boost Ad26.COV2.S 5*10^10 vp	4.5	Adults including elderly and stable co-morbidities	0 / 116	0 / 330	NR
Amplify, 2023 a	Non replicating viral vector	Ad26.COV2.S	Boost Ad26.COV2.S 2.5*10^10 vp	Boost Ad26.COV2.S 5*10^10 vp	4.5	Adults including elderly and stable co-morbidities	0 / 328	0 / 330	NR
Amplify, 2023 b	RNA based vaccine	BNT162b2	Boost Ad26.COV2.S 1*10^10 vp	Boost Ad26.COV2.S 5*10^10 vp	4.5	Adults including elderly and stable co-morbidities	0 / 106	0 / 326	NR
Amplify, 2023 b	RNA based vaccine	BNT162b2	Boost Ad26.COV2.S 2.5*10^10 vp	Boost Ad26.COV2.S 5*10^10 vp	4.5	Adults including elderly and stable co-morbidities	0 / 326	0 / 326	NR
Rose W, 2023	Non replicating viral vector	ChAdOx1	Boost BBV152	Boost ChAdOx1	3.0	Adults	0 / 99	0 / 101	NR
Rose W, 2023	Inactivated virus	BBV152	Boost ChAdOx1	Boost BBV152	3.0	Adults	0 / 102	0 / 102	NR
Rao C, 2022	Inactivated virus	CoronaVac	Boost SCB-2019	Boost CoronaVac	2.0	Adults who are healthy or have a stable pre-existing medical condition	0 / 214	0 / 216	NR
Tawinprai K, 2022	Inactivated virus	CoronaVac	Boost ChAdOx1	Boost BBIBP-CorV	0.5	Adults without active underlying disease	0 / 41	0 / 40	NR
Chuang C-H, 2022	Non replicating viral vector	ChAdOx1	Boost BNT162b2	Boost MVC-COV1901	5.9	Healthcare workers	0 / 83	0 / 85	NR
Chuang C-H, 2022	Non replicating viral vector	ChAdOx1	Boost mRNA-1273 (half dose)	Boost MVC-COV1901	5.9	Healthcare workers	0 / 85	0 / 85	NR
Chuang C-H, 2022	Non replicating viral vector	ChAdOx1	Boost mRNA-1273	Boost MVC-COV1901	5.9	Healthcare workers	0 / 85	0 / 85	NR
Reindl-Schwaighofer R, 2021	RNA based vaccine	BNT162b2 or mRNA-1273	Boost BNT162b2 or mRNA-1273	Boost Ad26COVS1	3	Kidney transplant recipients	4 / 99	4 / 99	1 [0.26 - 3.88]
Shinkai M, 2022	RNA based vaccine	BNT162b2	Boost S-268019-b	Boost BNT162b2	*	Adults	0 / 101	0 / 103	NR
Costa Clemens, 2022	Non replicating viral vector	ChadOx1	Boost 9 mcg SCB-2019 + alum	Boost ChadOx1	2.53	Adults	0 / 30	0 / 29	NR
Costa Clemens, 2022	Non replicating viral vector	ChadOx1	Boost 9 mcg SCB-2019 + CpG + alum	Boost ChadOx1	2.53	Adults	0 / 29	0 / 29	NR
Costa Clemens, 2022	Non replicating viral vector	ChadOx1	Boost 30 mcg SCB-2019 + CpG + alum	Boost ChadOx1	2.53	Adults	0 / 32	0 / 29	NR
Toledo-Romani ME, 2022 a	Protein subunit	FINLAY-FR-2-25 mcg	Boost FR-1	Boost FINLAY-FR-2	1	Healthy adults	0 / 58	0 / 55	NR
Estephan L, 2023 a	Protein subunit	MVC-COV1901	Boost 1/2 MVC-COV1901	Boost MVC-COV1901	5.16	Adults	0 / 78	0 / 78	NR
Estephan L, 2023 a	Protein subunit	MVC-COV1901	Boost 1/2 mRNA-1273	Boost MVC-COV1901	5.16	Adults	0 / 77	0 / 78	NR
Estephan L, 2023 a	Protein subunit	MVC-COV1901	Boost ChAdOx1	Boost MVC-COV1901	5.16	Adults	0 / 80	0 / 78	NR
Estephan L, 2023 c	RNA based vaccine	mRNA-1273	Boost MVC-COV1901	Boost 1/2 mRNA-1273	5.16	Adults	0 / 35	0 / 44	NR
Estephan L, 2023 c	RNA based vaccine	mRNA-1273	Boost ChAdOx1	Boost 1/2 mRNA-1273	5.16	Adults	0 / 42	0 / 44	NR
Estephan L, 2023 c	RNA based vaccine	mRNA-1273	Boost 1/2 MVC-COV1901	Boost 1/2 mRNA-1273	5.16	Adults	0 / 42	0 / 44	NR
Estephan L, 2023 b	Non replicating viral vector	ChadOx1	Boost MVC-COV1901	Boost ChadOx1	5.16	Adults	0 / 79	0 / 81	NR
Estephan L, 2023 b	Non replicating viral vector	ChadOx1	Boost mRNA-1273 (half dose)	Boost ChadOx1	5.16	Adults	0 / 82	0 / 81	NR
Natori Y, 2023	RNA based vaccine	BNT162b2	Boost Ad26.COV2.S	Boost BNT162b2	6	Transplant recipients	0 / 28	0 / 30	NR

r1: Number of events in intervention 1, r2: Number of events in intervention 2, N1: Number of patients analyzed in intervention 1; N2: Number of patients analyzed in intervention 2.

Second Boost

2nd booster VS 1st booster (tables)
No data

2nd booster VS 2nd booster (tables)

Immunogenicity
Geometric mean titre specific antibodies (D14)

Reference	Type of prime vaccination	Prime schedule	Intervention 1	Intervention 2	Follow up days	Participants	GMT1(N1)	GMT2(N2)	GMR [95% CI]	Evaluated by	Risk of bias
											A	B	C	D	E	Overall
Lien C, 2022 b	Protein subunit	MVC-COV1901	Boost MVC-COV1901+boost MVC-COV1901-Beta 15 mcg	Boost MVC-COV1901+boost MVC-COV1901	14	Adults including healthy or stable co-morbidities	28,179 (19)	21,078 (18)	1.33 [0.88, 2.01]	ELISA
Lien C, 2022 b	Protein subunit	MVC-COV1901	Boost MVC-COV1901+boost MVC-COV1901-Beta 25 mcg	Boost MVC-COV1901+boost MVC-COV1901	14	Adults including healthy or stable co-morbidities	21,638 (18)	21,078 (18)	1.02 [0.67, 1.55]	ELISA
Barda N, 2023	RNA based vaccine	BNT162b2	Boost BNT161b2-OMI 30mcg	Boost BNT162b2	30	Adults	4,774 (19)	5,409 (20)	0.88 [0.53, 1.48]	Automatic chemiluminescent microparticle immunoassay
Barda N, 2023	RNA based vaccine	BNT162b2	Boost BNT161b2-OMI 60mcg	Boost BNT162b2	30	Adults	5,959 (19)	5,409 (20)	1.10 [0.73, 1.65]	Automatic chemiluminescent microparticle immunoassay
Barda N, 2023	RNA based vaccine	BNT162b2	Boost BNT161b2-OMI 15/15mcg	Boost BNT162b2	30	Adults	7,487 (19)	5,409 (20)	1.38 [0.81, 2.37]	Automatic chemiluminescent microparticle immunoassay
Barda N, 2023	RNA based vaccine	BNT162b2	Boost BNT161b2-OMI 30/30mcg	Boost BNT162b2	30	Adults	4,672 (21)	5,409 (20)	0.86 [0.56, 1.33]	Automatic chemiluminescent microparticle immunoassay
Barda N, 2023	RNA based vaccine	BNT162b2	Boost BNT162b2 60mcg	Boost BNT162b2	30	Adults	3,611 (19)	5,409 (20)	0.67 [0.40, 1.11]	Automatic chemiluminescent microparticle immunoassay
Toback S, 2023	Inactivated virus	BBIBP-CorV	Boost NVX-CoV2373	Boost BBIBP-CorV	14	Healthy volunteers	388 (479)	215 (486)	1.8 [1.7, 1.9]	Chemiluminescence immunoassay (CLIA)

Geometric mean titre specific antibodies (≥D90)

Reference	Type of prime vaccination	Prime schedule	Intervention 1	Intervention 2	Follow up days	Participants	GMT1(N1)	GMT2(N2)	GMR [95% CI]	Evaluated by	Risk of bias
											A	B	C	D	E	Overall
Barda N, 2023	RNA based vaccine	BNT162b2	Boost BNT161b2-OMI 30mcg	Boost BNT162b2	90	Adults	4,304 (14)	2,981 (16)	1.44 [0.71, 2.92]	Automatic chemiluminescent microparticle immunoassay
Barda N, 2023	RNA based vaccine	BNT162b2	Boost BNT161b2-OMI 60mcg	Boost BNT162b2	90	Adults	3,901 (14)	2,981 (16)	1.31 [0.73, 2.33]	Automatic chemiluminescent microparticle immunoassay
Barda N, 2023	RNA based vaccine	BNT162b2	Boost BNT161b2-OMI 15/15mcg	Boost BNT162b2	90	Adults	4,605 (17)	2,981 (16)	1.54 [0.78, 3.05]	Automatic chemiluminescent microparticle immunoassay
Barda N, 2023	RNA based vaccine	BNT162b2	Boost BNT161b2-OMI 30/30mcg	Boost BNT162b2	90	Adults	3,001 (19)	2,981 (16)	1.01 [0.57, 1.78]	Automatic chemiluminescent microparticle immunoassay
Barda N, 2023	RNA based vaccine	BNT162b2	Boost BNT162b2 60mcg	Boost BNT162b2	90	Adults	2,314 (16)	2,981 (16)	0.78 [0.43, 1.39]	Automatic chemiluminescent microparticle immunoassay

Geometric mean titre neutralization assay against wild type (D14)

Reference	Type of prime vaccination	Prime schedule	Intervention 1	Intervention 2	Follow up days	Participants	GMT1(N1)	GMT2(N2)	GMR [95% CI]	Evaluated by	Risk of bias
											A	B	C	D	E	Overall
Lien C, 2022 b	Protein subunit	MVC-COV1901	Boost MVC-COV1901+boost MVC-COV1901-Beta 15 mcg	Boost MVC-COV1901+boost MVC-COV1901	28	Adults including healthy or stable co-morbidities	1,125 (19)	868 (18)	1.29 [0.82, 2.02]	Plaque reduction neutralization test
Lien C, 2022 b	Protein subunit	MVC-COV1901	Boost MVC-COV1901+boost MVC-COV1901-Beta 25 mcg	Boost MVC-COV1901+boost MVC-COV1901	28	Adults including healthy or stable co-morbidities	929 (18)	868 (18)	1.06 [0.68, 1.67]	Plaque reduction neutralization test
Branche A, 2023	Any COVID-19 vaccine	BNT162b2 OR mRNA-1273 OR Ad26.COV2.S	2nd Boost BNT162b2 Omicron BA.1	2nd Boost BNT162b2 Omicron BA.4/5	14	Adults including healthy or stable co-morbidities	27,000 (98)	34,109 (98)	0.79 [0.64, 0.97]	Pseudovirus Neutralization Assay
Branche A, 2022 a	Any COVID-19 vaccine	Completed primary and booster COVID-19 vaccine series, either homologous or heterologous	Boost mRNA Omicron + Beta vaccine	Boost Original mRNA-1273 vaccine	15	Adults	19,760 (198)	20,969 (97)	0.94 [0.73, 1.22]	Pseudovirion-based neutralisation assay
Branche A, 2022 a	Any COVID-19 vaccine	Completed primary and booster COVID-19 vaccine series, either homologous or heterologous	Boost mRNA Omicron + Delta vaccine	Boost Original mRNA-1273 vaccine	15	Adults	24,337 (99)	20,969 (97)	1.16 [0.85, 1.59]	Pseudovirion-based neutralisation assay
Branche A, 2022 a	Any COVID-19 vaccine	Completed primary and booster COVID-19 vaccine series, either homologous or heterologous	Boost mRNA Omicron + Original mRNA-1273 vaccine	Boost Original mRNA-1273 vaccine	15	Adults	26,125 (96)	20,969 (97)	1.25 [0.95, 1.64]	Pseudovirion-based neutralisation assay
Branche A, 2022 a	Any COVID-19 vaccine	Completed primary and booster COVID-19 vaccine series, either homologous or heterologous	Boost mRNA Omicron vaccine	Boost Original mRNA-1273 vaccine	15	Adults	19,167 (96)	20,969 (97)	0.91 [0.70, 1.20]	Pseudovirion-based neutralisation assay
He Q, 2022 b	Inactivated virus	CoronaVac or BBIBP-CorV	Boost BV-01-B5	Boost BV-01-B5	14	Healthy adults	1,327 (24)	1,327 (24)	2.06 [0.92, 4.59]	Pseudovirus neutralization assay
Barda N, 2023	RNA based vaccine	BNT162b2	Boost BNT161b2-OMI 30mcg	Boost BNT162b2	30	Adults	3,010 (18)	4,390 (20)	0.68 [0.32, 1.47]	Live Micro-neutralization assay
Barda N, 2023	RNA based vaccine	BNT162b2	Boost BNT161b2-OMI 60mcg	Boost BNT162b2	30	Adults	3,808 (19)	4,390 (20)	0.87 [0.42, 1.79]	Live Micro-neutralization assay
Barda N, 2023	RNA based vaccine	BNT162b2	Boost BNT161b2-OMI 15/15mcg	Boost BNT162b2	30	Adults	5,288 (19)	4,390 (20)	1.20 [0.63, 2.29]	Live Micro-neutralization assay
Barda N, 2023	RNA based vaccine	BNT162b2	Boost BNT161b2-OMI 30/30mcg	Boost BNT162b2	30	Adults	2,521 (20)	4,390 (20)	0.57 [0.28, 1.18]	Live Micro-neutralization assay
Barda N, 2023	RNA based vaccine	BNT162b2	Boost BNT162b2 60mcg	Boost BNT162b2	30	Adults	2,048 (18)	4,390 (20)	0.47 [0.21, 1.06]	Live Micro-neutralization assay
Winokur P, 2023	RNA based vaccine	BNT162b2	Boost biv BNT162b2 OMI 15/15mcg	Boost BNT162b2	30	Adults	6,945 (216)	7,377 (221)	0.94 [0.78, 1.04]	Recombinant SARS-CoV-2 neutralization assay
Winokur P, 2023	RNA based vaccine	BNT162b2	Boost BNT162b2 OMI 60mcg	Boost BNT162b2	30	Adults	8,447 (218)	7,377 (221)	1.14 [0.93, 1.40]	Recombinant SARS-CoV-2 neutralization assay
Winokur P, 2023	RNA based vaccine	BNT162b2	Boost biv BNT162b2 OMI 30/30mcg	Boost BNT162b2	30	Adults	9,355 (216)	7,377 (221)	1.27 [1.04, 1.54]	Recombinant SARS-CoV-2 neutralization assay
Winokur P, 2023	RNA based vaccine	BNT162b2	Boost BNT162b2 OMI 30mcg	Boost BNT162b2	30	Adults	6,815 (222)	7,377 (221)	0.92 [0.75, 1.13]	Recombinant SARS-CoV-2 neutralization assay
Winokur P, 2023	RNA based vaccine	BNT162b2	Boost BNT162b2 60mcg	Boost BNT162b2	30	Adults	8,244 (220)	7,377 (221)	1.11 [0.92, 1.34]	Recombinant SARS-CoV-2 neutralization assay
Tang R, 2023	Inactivated virus	Coronavac	Boost Coronovac/BoostAd5-nCoV IN	Boost Coronovac/boost Coronavac	14	Healthy adults	292 (117)	78 (116)	3.7 [2.6, 5.1]	Cytopathic effect-based microneutralization assay
Tang R, 2023	Inactivated virus	Coronavac	Boost Coronovac/Ad5-nCoV INCoV IM	Boost Coronovac/boost Coronavac	14	Healthy adults	746 (118)	78 (116)	9.5 [7.3, 12.3]	Cytopathic effect-based microneutralization assay
He Q, 2022 a	Protein subunit	CoronaVac or BBIBP-CorV	Boost V-01D-351	Boost CoronaVac	14	Healthy adults	5,609 (11)	501 (9)	11.20 [6.49, 19.30]	Pseudovirus neutralization assay
Toback S, 2023	Inactivated virus	BBIBP-CorV	Boost NVX-CoV2373	Boost BBIBP-CorV	14	Healthy volunteers	3,185 (479)	559 (486)	5.7 [5.1, 6.4]	Plaque Reduction Neutralization Test (PRNT)

Geometric mean titre neutralization assay against wild type (≥D90)

Reference	Type of prime vaccination	Prime schedule	Intervention 1	Intervention 2	Follow up days	Participants	GMT1(N1)	GMT2(N2)	GMR [95% CI]	Evaluated by	Risk of bias
											A	B	C	D	E	Overall
Barda N, 2023	RNA based vaccine	BNT162b2	Boost BNT161b2-OMI 30mcg	Boost BNT162b2	90	Adults	1,765 (14)	2,246 (15)	0.78 [0.27, 2.28]	Live Micro-neutralization assay
Barda N, 2023	RNA based vaccine	BNT162b2	Boost BNT161b2-OMI 60mcg	Boost BNT162b2	90	Adults	1,949 (14)	2,246 (15)	0.87 [0.35, 2.15]	Live Micro-neutralization assay
Barda N, 2023	RNA based vaccine	BNT162b2	Boost BNT161b2-OMI 15/15mcg	Boost BNT162b2	90	Adults	2,315 (17)	2,246 (15)	1.03 [0.45, 2.37]	Live Micro-neutralization assay
Barda N, 2023	RNA based vaccine	BNT162b2	Boost BNT161b2-OMI 30/30mcg	Boost BNT162b2	90	Adults	1,256 (17)	2,246 (15)	0.56 [0.25, 1.27]	Live Micro-neutralization assay
Barda N, 2023	RNA based vaccine	BNT162b2	Boost BNT162b2 60mcg	Boost BNT162b2	90	Adults	1,166 (16)	2,246 (15)	0.52 [0.22, 1.19]	Live Micro-neutralization assay

Geometric mean titre neutralization assay against Omicron variant (D14)

Reference	Type of prime vaccination	Prime schedule	Intervention 1	Intervention 2	Follow up days	Participants	GMT1(N1)	GMT2(N2)	GMR [95% CI]	Evaluated by	Risk of bias
											A	B	C	D	E	Overall
Lien C, 2022 b	Protein subunit	MVC-COV1901	Boost MVC-COV1901+boost MVC-COV1901-Beta 15 mcg	Boost MVC-COV1901+boost MVC-COV1901	28	Adults including healthy or stable co-morbidities	222 (19)	137 (18)	1.62 [0.86, 3.05]	Pseudovirus neutralisation assay
Lien C, 2022 b	Protein subunit	MVC-COV1901	Boost MVC-COV1901+boost MVC-COV1901-Beta 25 mcg	Boost MVC-COV1901+boost MVC-COV1901	28	Adults including healthy or stable co-morbidities	155 (18)	137 (18)	1.13 [0.67, 1.89]	Pseudovirus neutralisation assay
Branche A, 2023	Any COVID-19 vaccine	BNT162b2 OR mRNA-1273 OR Ad26.COV2.S	2nd Boost BNT162b2 Omicron BA.1	2nd Boost BNT162b2 Omicron BA.4/5	14	Adults including healthy or stable co-morbidities	3,546 (98)	5,939 (98)	0.60 [0.43, 0.83]	Pseudovirus neutralization assay
Branche A, 2022 a	Any COVID-19 vaccine	Completed primary and booster COVID-19 vaccine series, either homologous or heterologous	Boost mRNA Omicron + Beta vaccine	Boost Original mRNA-1273 vaccine	15	Adults	4,784 (198)	2,699 (97)	1.77 [1.24, 2.53]	Pseudotyped lentiviruses
Branche A, 2022 a	Any COVID-19 vaccine	Completed primary and booster COVID-19 vaccine series, either homologous or heterologous	Boost mRNA Omicron + Delta vaccine	Boost Original mRNA-1273 vaccine	15	Adults	4,503 (99)	2,699 (97)	1.67 [1.09, 2.54]	Pseudotyped lentiviruses
Branche A, 2022 a	Any COVID-19 vaccine	Completed primary and booster COVID-19 vaccine series, either homologous or heterologous	Boost mRNA Omicron + Original mRNA-1273 vaccine	Boost Original mRNA-1273 vaccine	15	Adults	5,322 (96)	2,699 (97)	1.97 [1.31, 2.95]	Pseudotyped lentiviruses
Branche A, 2022 a	Any COVID-19 vaccine	Completed primary and booster COVID-19 vaccine series, either homologous or heterologous	Boost mRNA Omicron vaccine	Boost Original mRNA-1273 vaccine	15	Adults	6,011 (96)	2,699 (97)	2.23 [1.52, 3.26]	Pseudotyped lentiviruses
He Q, 2022 b	Inactivated virus	CoronaVac or BBIBP-CorV	Boost BV-01-B5	Boost BV-01-B5	14	Healthy adults	500 (24)	500 (24)	3.68 [1.15, 11.77]	Pseudovirus neutralization assay
Barda N, 2023	RNA based vaccine	BNT162b2	Boost BNT161b2-OMI 30mcg	Boost BNT162b2	30	Adults	575 (18)	402 (20)	1.43 [0.67, 3.06]	Live Micro-neutralization assay
Barda N, 2023	RNA based vaccine	BNT162b2	Boost BNT161b2-OMI 60mcg	Boost BNT162b2	30	Adults	765 (19)	402 (20)	1.90 [0.82, 4.44]	Live Micro-neutralization assay
Barda N, 2023	RNA based vaccine	BNT162b2	Boost BNT161b2-OMI 15/15mcg	Boost BNT162b2	30	Adults	1,062 (19)	402 (20)	2.64 [1.07, 6.53]	Live Micro-neutralization assay
Barda N, 2023	RNA based vaccine	BNT162b2	Boost BNT161b2-OMI 30/30mcg	Boost BNT162b2	30	Adults	478 (20)	402 (20)	1.19 [0.50, 2.87]	Live Micro-neutralization assay
Barda N, 2023	RNA based vaccine	BNT162b2	Boost BNT162b2 60mcg	Boost BNT162b2	30	Adults	188 (18)	402 (20)	0.47 [1.19, 1.17]	Live Micro-neutralization assay
Winokur P, 2023	RNA based vaccine	BNT162b2	Boost biv BNT162b2 OMI 15/15mcg	Boost BNT162b2	30	Adults	884 (216)	663 (221)	1.33 [0.99, 1.78]	Recombinant SARS-CoV-2 neutralization assay
Winokur P, 2023	RNA based vaccine	BNT162b2	Boost BNT162b2 OMI 60mcg	Boost BNT162b2	30	Adults	1,836 (218)	663 (221)	2.76 [2.08, 3.67]	Recombinant SARS-CoV-2 neutralization assay
Winokur P, 2023	RNA based vaccine	BNT162b2	Boost biv BNT162b2 OMI 30/30mcg	Boost BNT162b2	30	Adults	1,140 (216)	663 (221)	1.71 [1.27, 2.32]	Recombinant SARS-CoV-2 neutralization assay
Winokur P, 2023	RNA based vaccine	BNT162b2	Boost BNT162b2 OMI 30mcg	Boost BNT162b2	30	Adults	1,346 (222)	663 (221)	2.03 [1.51, 2.72]	Recombinant SARS-CoV-2 neutralization assay
Winokur P, 2023	RNA based vaccine	BNT162b2	Boost BNT162b2 60mcg	Boost BNT162b2	30	Adults	821 (220)	663 (221)	1.23 [0.92, 1.65]	Recombinant SARS-CoV-2 neutralization assay
Tang R, 2023	Inactivated virus	Coronavac	Boost Coronovac/BoostAd5-nCoV IN	Boost Coronovac/boost Coronavac	14	Healthy adults	63 (117)	21 (116)	3.0 [2.3, 3.8]	Pseudovirus neutralisation tests
Tang R, 2023	Inactivated virus	Coronavac	Boost Coronovac/Ad5-nCoV INCoV IM	Boost Coronovac/boost Coronavac	14	Healthy adults	117 (118)	21 (116)	5.6 [4.6, 7.3]	Pseudovirus neutralisation tests
He Q, 2022 a	Protein subunit	CoronaVac or BBIBP-CorV	Boost V-01D-351	Boost CoronaVac	14	Healthy adults	192 (11)	16 (9)	12 [3.33, 43.19]	Pseudovirus neutralization assay

Geometric mean titre neutralization assay against Omicron variant (≥D90)

Reference	Type of prime vaccination	Prime schedule	Intervention 1	Intervention 2	Follow up days	Participants	GMT1(N1)	GMT2(N2)	GMR [95% CI]	Evaluated by	Risk of bias
											A	B	C	D	E	Overall
Barda N, 2023	RNA based vaccine	BNT162b2	Boost BNT161b2-OMI 30mcg	Boost BNT162b2	90	Adults	328 (14)	154 (15)	2.12 [0.57, 7.87]	Live Micro-neutralization assay
Barda N, 2023	RNA based vaccine	BNT162b2	Boost BNT161b2-OMI 60mcg	Boost BNT162b2	90	Adults	512 (14)	154 (15)	3.32 [1.25, 8.83]	Live Micro-neutralization assay
Barda N, 2023	RNA based vaccine	BNT162b2	Boost BNT161b2-OMI 15/15mcg	Boost BNT162b2	90	Adults	435 (17)	154 (15)	2.82 [0.93, 8.49]	Live Micro-neutralization assay
Barda N, 2023	RNA based vaccine	BNT162b2	Boost BNT161b2-OMI 30/30mcg	Boost BNT162b2	90	Adults	246 (17)	154 (15)	1.60 [0.53, 4.79]	Live Micro-neutralization assay
Barda N, 2023	RNA based vaccine	BNT162b2	Boost BNT162b2 60mcg	Boost BNT162b2	90	Adults	95 (16)	154 (15)	0.61 [0.22, 1.72]	Live Micro-neutralization assay

Safety
Serious adverse events

Reference	Type of prime vaccination	Prime schedule	Intervention 1	Intervention 2	Follow up months	Participants	r1/N1	r2/N2	RR [95% CI]	Risk of bias
										A	B	C	D	E	Overall
Lien C, 2022 b	Protein subunit	MVC-COV1901	Boost MVC-COV1901+boost MVC-COV1901-Beta 15 mcg	Boost MVC-COV1901+boost MVC-COV1901	0.9	Adults including healthy or stable co-morbidities	0 / 21	0 / 21	NR
Lien C, 2022 b	Protein subunit	MVC-COV1901	Boost MVC-COV1901+boost MVC-COV1901-Beta 25 mcg	Boost MVC-COV1901+boost MVC-COV1901	0.9	Adults including healthy or stable co-morbidities	0 / 20	0 / 21	NR
Lee I, 2023 a	Any COVID-19 vaccine	Any authorized COVID	Boost mRNA-1273.529	Boost mRNA-1273	1	Aged at least 16 years including healthy, elderly and/or stable co-morbidities	5 / 367	1 / 357	4.86 [0.57 - 41.43]
Lee l, 2023 b	Any COVID-19 vaccine	Any authorized COVID-19 vaccine of: BNT162b2, mRNA-1273, ChAdOx1, Ad26.COV2.S	Boost mRNA-1273.214	Boost mRNA-1273	1	Aged at least 16 years including healthy, elderly and/or stable co-morbidities	6 / 1422	5 / 1402	1.18 [0.36 - 3.87]
Branche A, 2023	Any COVID-19 vaccine	BNT162b2 OR mRNA-1273 OR Ad26.COV2.S	2nd Boost BNT162b2 Omicron BA.1	2nd Boost BNT162b2 Omicron BA.4/5	29	Adults including healthy or stable co-morbidities	0 / 101	0 / 101	NR
He Q, 2022 b	Inactivated virus	CoronaVac or BBIBP-CorV	Boost BV-01-B5	Boost BV-01-B5	1	Healthy adults	0 / 24	0 / 24	NR
Winokur P, 2023	RNA based vaccine	BNT162b2	Boost biv BNT162b2 OMI 15/15mcg	Boost BNT162b2	1.7	Adults	1 / 305	2 / 305	0.5 [0.05 - 5.49]
Winokur P, 2023	RNA based vaccine	BNT162b2	Boost BNT162b2 OMI 60mcg	Boost BNT162b2	1.7	Adults	0 / 306	2 / 305	0.2 [0.01 - 4.14]
Winokur P, 2023	RNA based vaccine	BNT162b2	Boost biv BNT162b2 OMI 30/30mcg	Boost BNT162b2	1.7	Adults	2 / 316	2 / 305	0.97 [0.14 - 6.81]
Winokur P, 2023	RNA based vaccine	BNT162b2	Boost BNT162b2 OMI 30mcg	Boost BNT162b2	1.7	Adults	3 / 307	2 / 305	1.49 [0.25 - 8.86]
Winokur P, 2023	RNA based vaccine	BNT162b2	Boost BNT162b2 60mcg	Boost BNT162b2	1.7	Adults	0 / 302	2 / 305	0.2 [0.01 - 4.19]
Munro APS, 2022	RNA based vaccine	BNT162b2 + boost BNT162b2	Boost BNT162b2	Boost half dose m-RNA 1273	1.7	Healthy adults	1 / 39	0 / 39	3 [0.13 - 71.37]
Munro APS, 2022	Non replicating viral vector	ChadOx1 + boost BNT162b2	Boost BNT162b2	Boost half dose m-RNA 1273	1.7	Healthy adults	2 / 44	0 / 44	5 [0.25 - 101.12]
Tang R, 2023	Inactivated virus	Coronavac	Boost Coronovac/BoostAd5-nCoV IN	Boost Coronovac/boost Coronavac	0.9	Healthy adults	0 / 117	0 / 119	NR
Tang R, 2023	Inactivated virus	Coronavac	Boost Coronovac/Ad5-nCoV INCoV IM	Boost Coronovac/boost Coronavac	0.9	Healthy adults	0 / 120	0 / 119	NR
He Q, 2022 a	Protein subunit	CoronaVac or BBIBP-CorV	Boost V-01D-351	Boost CoronaVac	0.9	Healthy adults	0 / 11	0 / 9	NR
Toback S, 2023	Inactivated virus	BBIBP-CorV	Boost NVX-CoV2373	Boost BBIBP-CorV	1	Healthy volunteers	0 / 497	0 / 501	NR

r1: Number of events in intervention 1, r2: Number of events in intervention 2, N1: Number of patients analyzed in intervention 1; N2: Number of patients analyzed in intervention 2.

All-cause mortality

Reference	Type of prime vaccination	Prime schedule	Intervention 1	Intervention 2	Follow up months	Participants	r1/N1	r2/N2	RR [95% CI]	Risk of bias
										A	B	C	D	E	Overall
Tang R, 2023	Inactivated virus	Coronavac	Boost Coronovac/BoostAd5-nCoV IN	Boost Coronovac/boost Coronavac	0.9	Healthy adults	0 / 117	0 / 119	NR
Tang R, 2023	Inactivated virus	Coronavac	Boost Coronovac/Ad5-nCoV INCoV IM	Boost Coronovac/boost Coronavac	0.9	Healthy adults	0 / 120	0 / 119	NR
Lien C, 2022 b	Protein subunit	MVC-COV1901	Boost MVC-COV1901+boost MVC-COV1901-Beta 15 mcg	Boost MVC-COV1901+boost MVC-COV1901	0.9	Adults including healthy or stable co-morbidities	0 / 21	0 / 21	NR
Lien C, 2022 b	Protein subunit	MVC-COV1901	Boost MVC-COV1901+boost MVC-COV1901-Beta 25 mcg	Boost MVC-COV1901+boost MVC-COV1901	0.9	Adults including healthy or stable co-morbidities	0 / 20	0 / 21	NR
Lee I, 2023 a	Any COVID-19 vaccine	Any authorized COVID	Boost mRNA-1273.529	Boost mRNA-1273	4.6	Aged at least 16 years including healthy, elderly and/or stable co-morbidities	0 / 367	0 / 357	NR
Lee l, 2023 b	Any COVID-19 vaccine	Any authorized COVID-19 vaccine of: BNT162b2, mRNA-1273, ChAdOx1, Ad26.COV2.S	Boost mRNA-1273.214	Boost mRNA-1273	2.9	Aged at least 16 years including healthy, elderly and/or stable co-morbidities	0 / 1422	0 / 1402	NR
Winokur P, 2023	RNA based vaccine	BNT162b2	Boost biv BNT162b2 OMI 15/15mcg	Boost BNT162b2	1.7	Adults	0 / 305	0 / 305	NR
Winokur P, 2023	RNA based vaccine	BNT162b2	Boost BNT162b2 OMI 60mcg	Boost BNT162b2	1.7	Adults	0 / 306	0 / 305	NR
Winokur P, 2023	RNA based vaccine	BNT162b2	Boost biv BNT162b2 OMI 30/30mcg	Boost BNT162b2	1.7	Adults	0 / 316	0 / 305	NR
Winokur P, 2023	RNA based vaccine	BNT162b2	Boost BNT162b2 OMI 30mcg	Boost BNT162b2	1.7	Adults	0 / 307	0 / 305	NR
Winokur P, 2023	RNA based vaccine	BNT162b2	Boost BNT162b2 60mcg	Boost BNT162b2	1.7	Adults	0 / 302	0 / 305	NR

r1: Number of events in intervention 1, r2: Number of events in intervention 2, N1: Number of patients analyzed in intervention 1; N2: Number of patients analyzed in intervention 2.

COVID-19 PRIME VACCINATION: Last search date December 14, 2022.

Click here to see Covid-19 prime vaccination studies

Trials reports under extraction

In addition to the below included trials, we have included and presently extracting 12 new vaccine randomized trials

Description of primary studies

In this table, we report the main characteristics of the COVID-19 vaccine candidates from RCTs identified, in addition to the overall risk of bias assessment.

For prime vaccination, early phase trials were extracted only when the dose has been selected. Results from phase 1-2 studies are included in forest plots for the chosen vaccine dose and schedule only. List of early phases included but not extracted are detailed on here .

Search studies

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Trial	Type	Comparisons		Design	Participants	Sample size	Overall risk of bias Highest assessment	Full description
		Intervention 1	Intervention 2
NCT05249816 Novavax, Inc Toback S, medRxiv, 2023 Full text Commentary	Heterologous booster	2 or 3 doses of BBIBP-CorV/Boost NVX-CoV2373	2 or 3 doses of BBIBP-CorV/Boost BBIBP-CorV	RCT Phase 3	Healthy adult volunteers who had received a complete 2 doses series of BBIBP-CorV vaccine with or without a a third dose booster of BBIBP-CorV vaccine in 2 centres in UAE	N= 1000	Some concerns Details	Full description
CTRI/2022/01/039366 Biological E Limited Thuluva S, medRxiv, 2023 b Full text Commentary	Protein subunit	BBV152/Boost BECOV2	BBV152/Boost Placebo	RCT Phase 3	Adults including elderly and co-morbidities in 7 centres in India.	N= 208	Low Details	Full description
NCT05204589 Institute of Biotechnology (Beijing, China); CanSino Biologics Li X, SSRN, 2023 Full text Commentary	Heterologous vaccination scheme	Any inactivated COVID-19 vaccine/Boost aerosolized Ad5-nCoV	Any inactivated COVID-19 vaccine/Boost homologous	RCT Phase 3	Healthy adults with no history of COVID-19 in multiple centres in China.	N= 420	Some concerns Details	Full description
CTRI/2022/04/042017 Novavax Kulkarni P, Research Square, 2023 a Full text Commentary	Heterologous booster	ChAdOx1/Boost SII-NVX-CoV2373	ChAdOx1 /Boost ChAdOx1	RCT Phase 3	Adults including elderly and controlled co-morbidities,primed with viral vector and inactivated vaccines, with no history of COVID-19 in 8 centres in India.	N= 186	Some concerns Details	Full description
CTRI/2022/01/039366 Biological E Limited Thuluva S, medRxiv, 2023 a Full text Commentary	Heterologous vaccination scheme	ChAdOx1/Boost BECOV2	ChadOx1/boostPlacebo	RCT Phase 3	Adults including elderly and co-morbidities in 7 centres in India.	N= 208	Low Details	Full description
ChiCTR2100051391 Beijing Wantai Biological Pharmacy Enterprise Co., Ltd. Xia N, Research Square, 2023 Full text Commentary	Heterologous booster	Any COVID-19 vaccine/Boost dNS1-RBD	Any COVID-19 vaccine/Boost Placebo	RCT Phase 3	Adultsincluding healthy and mild stable co-morbidities without prior COVID-19 history in 33 centres in Philippines, South Africa, Colombia and Vietnam	N= 17210	Some concerns Details	Full description
CTRI/2022/04/042017 Novavax; Bharat Biotech Kulkarni P , Research Square, 2023 b Full text Commentary	Heterologous booster	BBV152/Boost SII-NVX-CoV2373	BBV152 Booster	RCT Phase 3	Adults including elderly and controlled co-morbidities, primed with viral vector and inactivated vaccines, with no history of COVID-19 in 8 centres in India.	N= 186	Some concerns Details	Full description
jRCT2051210164 VLP Therapeutics Japan; Pfizer/BioNTech + Fosun Pharma Akahata W, SSRN, 2023 a Full text Full text Commentary Commentary	saRNA based vaccine	BNT162b2/Boost VLPCOV-01 0.3 mcg BNT162b2/Boost VLPCOV-01 1 mcg BNT162b2/Boost VLPCOV-01 3 mcg	BNT162b2/boostBNT	RCT Phase 1	Healthy adults, 18 to 55 years of age, SARS-CoV-2 infection-free in a single centre in Japan.	N= 46	Some concerns Details	Full description
jRCT2051210164 VLP Therapeutics Japan; Pfizer/BioNTech + Fosun Pharma Akahata W , SSRN, 2023 b Full text Full text Commentary Commentary	saRNA based vaccine	BNT162b2/Boost VLPCOV-01 0.3 mcg BNT162b2/Boost VLPCOV-01 1 mcg BNT162b2/Boost VLPCOV-01 3 mcg	BNT162b2/boostBNT	RCT Phase 1	Healthy adults, ≥65 years years of age, SARS-CoV-2 infection-free in a single centre in Japan.	N= 46	Some concerns Details	Full description
NCT05583357 Livzon Pharmaceutical Group Inc He Q, J. Clin. Med., 2022 a Full text Commentary	Protein subunit	Any inactivated COVID-19 vaccine/Boost inactivated COVID-19 vaccine/Boost V-01D-351	Any inactivated COVID-19 vaccine/Boost inactivated COVID-19 vaccine/Boost CoronaVac	RCT Phase 1	Healthy adults with no history of SARS-CoV-2 infection and 3 doses of CoronaVac or BBIBP-CorV in one centre in China	N= 20	Some concerns Details	Full description

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COVID-19 vaccine effectiveness(Randomized evidence)

Methods

Latest news:Last search date July 30, 2023. No further screening is planned after this date. Extraction is ongoing for all pending studies.

meta-COVID

COVID-19 BOOSTER DOSE VACCINATION: updated daily

COVID-19 PRIME VACCINATION: Last search date December 14, 2022.

Trials reports under extraction

Description of primary studies

Search studies

COVID-19 vaccine effectiveness
(Randomized evidence)