Covid-19 living Data

COVID-19 vaccine effectiveness
(Randomized evidence)

Methods

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 .

On December 7, 2022, we published results of the systematic review "Efficacy and safety of COVID‐19 vaccines" which 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:

Vaccine types

COVID-19 BOOSTER DOSE VACCINATION: updated daily

Vaccine efficacy, immunogenicity and safety of booster vs no booster (tables)

Reference	Type of prime vaccination	Prime schedule	Intervention 1	Intervention 2	Follow up months	Participants	r1/N1	r2/N2	Vaccine efficacy [95% CI]	Risk of bias
	A	B	C	D	E	Overall
Toledo-Romani ME, 2022 b Full text Full text	Protein subunit	FINLAY-FR-2-25 mcg	Boost FINLAY-FR-1-50 mcg	Placebo	*	Adults	0 / 13828	6 / 12486	100.0 [*, 100]

Efficacy
Severe or critical COVID-19 after complete vaccination
Confirmed symptomatic COVID-19 after complete vaccination

Reference	Type of prime vaccination	Prime schedule	Intervention 1	Intervention 2	Follow up months	Participants	r1/N1	r2/N2	VE [95% CI]
	A	B	C	D	E	Overall
Moreira E D, 2022	RNA based vaccine	BNT162b2	Boost BNT162b2	Placebo	2.5	Adults and adolescents	6 / 4695	123 / 4671	95.3 [89.5, 98.3]
Wang X-Y, 2022	Inactivated virus	BBIBP-CorV or CoronaVac	Boost V-01	Placebo	2	Healthy adults	NR	NR	47.8 [22.6, 64.7]
Toledo-Romani ME, 2022 b	Protein subunit	FINLAY-FR-2-25 mcg	Boost FINLAY-FR-1-50 mcg	Placebo	*	Adults	NR	NR	92.0 [80.4, 96.7]

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
Geometric mean titre neutralization assay against -wild type

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
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 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 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
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
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.
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

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- omicron

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		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		Adults	901 (75)	58 (72)	15.0 [10.7, 21.1]	Plaque Reduction Neutralization Assay (PRNT50)

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
Tabarsi P, 2022	Any COVID-19 vaccine	Any Covid-19 vaccine	Boost SpikoGen	Placebo	0.5	Adults	0 / 250	0 / 50	NR
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]
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 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 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
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
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]
Vadrevu KM, 2022	Inactivated virus	BBV152	Boost BBV152	Placebo	1	Adolescents and adults	0 / 80	0 / 87	NR
Toledo-Romani ME, 2022 b	Protein subunit	FINLAY-FR-2-25 mcg	Boost FINLAY-FR-1-50 mcg	Placebo	2.7	Adults	1 / 14677	3 / 14675	0.33 [0.03 - 3.2]
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
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]
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

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
Vadrevu KM, 2022	Inactivated virus	BBV152	Boost BBV152	Placebo	1	Adolescents and adults	0 / 80	0 / 87	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
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
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

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.

Vaccine efficacy, immunogenicity and safety of booster VS booster (tables)

Immunogenicity
Geometric mean titre specific antibodies

Reference	Type of prime vaccination	Prime schedule	Intervention 1	Intervention 2	Follow up days	Participants	GMT Boost1 (N1)	GMT Boost2 (N2)	GMR [95% CI]	Evaluated by	Risk of bias
											A	B	C	D	E	Overall
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
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
Cao Y, 2021	Inactivated virus	CoronaVac	Boost ZF2001	Boost CoronaVac	14	Healthcare workers	10,417 (81)	7,496 (40)	*1.38 [, ]*	ELISA
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.
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
Puthanakit T, 2022 b	Any COVID-19 vaccine	CoronaVac 3 mcg (0.5mL)/BNT162b2 30 mcg or BNT162b2 20 mcg	Boost BNT162b2 15mcg	Boost BNT162b2 30mcg	14	Adolescents	NR (18)	2,828 (17)	0.91 [0.73, 1.13]	ELISA
Puthanakit T, 2022 b	Any COVID-19 vaccine	CoronaVac 3 mcg (0.5mL)/BNT162b2 30 mcg or BNT162b2 20 mcg	Boost BNT162b2 10mcg	Boost BNT162b2 30mcg	14	Adolescents	NR (17)	2,828 (17)	0.73 [0.58, 0.91]	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
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
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
Launay O, 2022	RNA based vaccine	BNT162b2	Boost MV B.1.351	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
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

Geometric mean titre neutralization assay against -wild type

Reference	Type of prime vaccination	Prime schedule	Intervention 1	Intervention 2	Follow up days	Participants	GMT Boost1 (N1)	GMT Boost2 (N2)	GMR [95% CI]	Evaluated by	Risk of bias
											A	B	C	D	E	Overall
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
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
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)
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
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)
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
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
Puthanakit T, 2022 b	Any COVID-19 vaccine	CoronaVac 3 mcg (0.5mL)/BNT162b2 30 mcg or BNT162b2 20 mcg	Boost BNT162b2 15mcg	Boost BNT162b2 30mcg	14	Adolescents	NR (*)	NR (*)	NR	*
Puthanakit T, 2022 b	Any COVID-19 vaccine	CoronaVac 3 mcg (0.5mL)/BNT162b2 30 mcg or BNT162b2 20 mcg	Boost BNT162b2 10mcg	Boost BNT162b2 30mcg	14	Adolescents	NR (*)	NR (*)	NR	*
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
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
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]	Pseudovirion-based neutralisation 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
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
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)
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
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
Jin P, 2022 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
Launay O, 2022	RNA based vaccine	BNT162b2	Boost MV B.1.351	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
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
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
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)

Geometric mean titre neutralization assay- omicron

Reference	Type of prime vaccination	Prime schedule	Intervention 1	Intervention 2	Follow up days	Participants	GMT Boost1 (N1)	GMT Boost2 (N2)	GMR [95% CI]	Evaluated by	Risk of bias
											A	B	C	D	E	Overall
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
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
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)
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
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
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.
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
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
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)
Chuang C-H, 2022	Non replicating viral vector	ChAdOx1	Boost mRNA-1273 (half dose)	Boost BNT162b2	28	Healthcare workers	204 (30)	146 (30)	5.51 [3.42, 8.90]	Live virus neutralization
Chuang C-H, 2022	Non replicating viral vector	ChAdOx1	Boost mRNA-1273	Boost BNT162b2	28	Healthcare workers	250 (30)	146 (30)	6.75 [4.30, 10.61]	Live virus neutralization
Chuang C-H, 2022	Non replicating viral vector	ChAdOx1	Boost MVC-COV1901	Boost BNT162b2	28	Healthcare workers	37 (30)	146 (30)	0.25 [0.16, 0.38]	Live virus neutralization
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)
Jin P, 2022 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
Launay O, 2022	RNA based vaccine	BNT162b2	Boost MV B.1.351	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
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
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
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)

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
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]
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
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]
Shinkai M, 2022	RNA based vaccine	BNT162b2	Boost S-268019-b	Boost BNT162b2	NR	Adults	0 / 101	0 / 103	NR
Poh XY, 2022	RNA based vaccine	BNT162b2	Boost mRNA-1273	Boost BNT162b2	28	Adults	0 / 48	0 / 50	NR
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]
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
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]
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
Li J, 2022	Inactivated virus	CoronaVac	Boost Ad5-vectored	Boost Coronavac	1	Healthy adults	0 / 96	0 / 102	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
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]
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
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]
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]
Al Kaabi N, 2023	Inactivated virus	BBIBP-CorV	Boost NVSI-06-09	Boost BBIBP-CorV	1	Healthy adults	0 / 260	0 / 256	NR
Jin P, 2022 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]
Launay O, 2022	RNA based vaccine	BNT162b2	Boost MV B.1.351	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]
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]
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
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]
Wang L, 2022	Inactivated virus	CoronaVax	Boost CoronaVax	Boost CoronaVax	1	Children and adolescents	1 / 173	0 / 173	3 [0.12 - 73.14]

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
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
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
Shinkai M, 2022	RNA based vaccine	BNT162b2	Boost S-268019-b	Boost BNT162b2	*	Adults	0 / 101	0 / 103	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]
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
Corominas J, 2023	RNA based vaccine	BNT162b2	Boost PHH-1V	Boost BNT162b2	3.2	Healthy adults	0 / 513	0 / 252	NR
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
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	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
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
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
Chuang C-H, 2022	Non replicating viral vector	ChAdOx1	Boost mRNA-1273 (half dose)	Boost BNT162b2	5.9	Healthcare workers	0 / 85	0 / 83	NR
Chuang C-H, 2022	Non replicating viral vector	ChAdOx1	Boost mRNA-1273	Boost BNT162b2	5.9	Healthcare workers	0 / 85	0 / 83	NR
Chuang C-H, 2022	Non replicating viral vector	ChAdOx1	Boost MVC-COV1901	Boost BNT162b2	5.9	Healthcare workers	0 / 85	0 / 83	NR
Launay O, 2022	RNA based vaccine	BNT162b2	Boost MV B.1.351	Boost BNT162b2	0.5	Adults including healthy or stable co-morbidities	0 / 80	0 / 82	NR
Launay O, 2022	RNA based vaccine	BNT162b2	Boost MV D614	Boost BNT162b2	0.5	Adults including healthy or stable co-morbidities	0 / 85	0 / 82	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
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
Wang L, 2022	Inactivated virus	CoronaVax	Boost CoronaVax	Boost CoronaVax	1	Children and adolescents	0 / 173	0 / 173	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.

Vaccine efficacy and safety for vaccine vs placebo / no vaccine (forest plots)

Vaccine efficacy and safety for vaccine vs vaccine (forest plots)

Vaccine efficacy, immunogenicity and safety of heterologous vs homologous vaccination (tables)

Immunogenicity
Geometric mean titre specific antibodies

Reference	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
Janssen C, 2022	1 dose BNT162b2/1 dose mRNA-1273	2 doses BNT162b2	28	Adults	3,706 (96)	2,698 (94)	1.37 [1.10, 1.72]	ELISA
Janssen C, 2022	1 dose mRNA-1273 /1 dose BNT162b2	2 doses mRNA-1273	28	Adults	2,690 (103)	3,995 (97)	0.67 [0.55, 0.82]	ELISA
Puthanakit T, 2022 a	CoronaVac followed by BNT162b2 30 at 6week interva	CoronaVac followed by BNT162b2 30 at 3week interva	21	Adolescents	112 (20)	77 (20)	1.28 [1.09, 1.51]	ELISA
Puthanakit T, 2022 a	CoronaVac followed by BNT162b2 20 at 3week interva	CoronaVac followed by BNT162b2 30 at 3week interva	21	Adolescents	84 (17)	77 (20)	0.95 [0.80, 1.13]	ELISA
Puthanakit T, 2022 a	CoronaVac followed by BNT162b2 20 at 6week interva	CoronaVac followed by BNT162b2 30 at 3week interva	21	Adolescents	74 (19)	77 (20)	1.10 [0.94, 1.30]	ELISA
Chen C, 2022	1 dose ChAdOx1 / 1 dose MVC-COV1901	ChAdOx1	10	Healthy adults	8 (50)	5 (50)	1.5 [1.2, 1.9]	ELISA
Li J, 2022	1 dose CoronaVac / 1 dose Ad5-vectored	2 doses CoronaVac	14	Healthy adults	942 (51)	154 (50)	6.11 [3.90, 9.57]	ELISA

N1: 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

Geometric mean titre neutralizing antibodies

Reference	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
Janssen C, 2022	1 dose BNT162b2/1 dose mRNA-1273	2 doses BNT162b2	28	Adults	523 (96)	396 (94)	1.31 [1.02, 1.69]	CPE (cytopathic effect)-based virus neutralization test (VNT)
Chen C, 2022	1 dose ChAdOx1 / 1 dose MVC-COV1901	ChAdOx1	10	Healthy adults	202 (50)	78 (50)	2.6 [1.7, 4.0]	Plaque reduction neutralization
Li J, 2022	1 dose CoronaVac / 1 dose Ad5-vectored	2 doses CoronaVac	14	Healthy adults	54 (51)	13 (50)	4.3 [2.5, 7.3]	CPE-based microneutralization assay-wild-type
Jin P, 2022 b	CoronaVac/Ad5-nCoV	CoronaVac	14	Elderly	71 (48)	9 (47)	7.62 [4.44, 13.1]	Microneutralization assay

N1: 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

Safety
Serious adverse events

Reference	Intervention 1	Intervention 2	Follow up months	Participants	r1/N1	r2/N2	RR [95% CI]	Risk of bias
								A	B	C	D	E	Overall
Macchia A, 2022	Gam-COVID-Vac rAd26-S	Gam-COVID-Vac rAd26-S/BBIBP-CorV	1	Adults	0 / 87	0 / 65	NR
Stuart A, 2021 a	1 dose ChAdOx1 followed by 1 dose NVX-CoV2373	2 doses ChAdOx1	NR	Older adults	1 / 179	3 / 180	0.34 [0.04 - 3.19]
Stuart A, 2021 a	1 dose ChAdOx1 followed by 1 dose mRNA-1273	2 doses ChAdOx1	NR	Older adults	3 / 181	3 / 180	0.99 [0.2 - 4.86]
Stuart A, 2021 b	1 dose BNT162b2 followed by 1 dose NVX-CoV2373	2 doses BNT162b2	NR	Older adults	3 / 180	2 / 175	1.46 [0.25 - 8.62]
Stuart A, 2021 b	1 dose BNT162b2 followed by 1 dose mRNA-1273	2 doses BNT162b2	NR	Older adults	3 / 177	2 / 175	1.48 [0.25 - 8.77]
Janssen C, 2022	1 dose BNT162b2/1 dose mRNA-1273	2 doses BNT162b2	0.9	Adults	0 / 102	0 / 101	NR
Janssen C, 2022	1 dose mRNA-1273 /1 dose BNT162b2	2 doses mRNA-1273	0.9	Adults	0 / 106	0 / 105	NR
Liu X, 2022	1 dose ChAdOx1/ 1 dose BNT162b2	2 doses ChAdOx1	8.3	Adults	2 / 114	1 / 115	2.02 [0.19 - 21.94]
Liu X, 2022	1 dose BNT162b2 /1 dose ChAdOx1	2 doses BNT162b2	8.3	Adults	2 / 115	1 / 119	2.07 [0.19 - 22.51]
Bánki Z, 2022	1 dose ChAdOx1/ 1 dose BNT162b2	ChAdOx1	1	Healthy adults	1 / 114	0 / 108	2.84 [0.12 - 69.03]
Chen C, 2022	1 dose ChAdOx1 / 1 dose MVC-COV1901	ChAdOx1	0.9	Healthy adults	0 / 50	0 / 50	NR
Li J, 2022	1 dose CoronaVac / 1 dose Ad5-vectored	2 doses CoronaVac	1	Healthy adults	0 / 51	0 / 50	NR
Jin P, 2022 b	CoronaVac/Ad5-nCoV	CoronaVac	6	Elderly	1 / 50	2 / 50	0.5 [0.05 - 5.33]
Niyomnaitham S, 2022 a	CoronaVac/ChAdOx1	BNT162b2	2.8	Adults	0 / 30	0 / 26	NR
Niyomnaitham S, 2022 a	CoronaVac/BNT162b2	BNT162b2	2.8	Adults	0 / 30	0 / 26	NR
Niyomnaitham S, 2022 a	ChAdOx1/CoronaVac	BNT162b2	2.8	Adults	0 / 29	0 / 26	NR
Niyomnaitham S, 2022 a	ChAdOx1/BNT162b2	BNT162b2	2.8	Adults	0 / 26	0 / 26	NR
Niyomnaitham S, 2022 a	BNT162b2/CoronaVac	BNT162b2	2.8	Adults	0 / 29	0 / 26	NR
Niyomnaitham S, 2022 a	BNT162b2+ChAdOx1	BNT162b2	2.8	Adults	0 / 30	0 / 26	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	Intervention 1	Intervention 2	Follow up months	Participants	r1/N1	r2/N2	RR [95% CI]	Risk of bias
	A	B	C	D	E	Overall
Chen C, 2022	1 dose ChAdOx1 / 1 dose MVC-COV1901	ChAdOx1	0.9	Healthy adults	0 / 50	0 / 50	NR

Vaccine efficacy and safety against variants of concern (forest plots)

Trials reports under extraction

In addition to the below included trials, we have included and presently extracting 18 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

Sort by: Most recent studiesFirst Author
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Trial	Type	Comparisons		Design	Participants	Sample size	Overall risk of bias Highest assessment	Full description
		Intervention 1	Intervention 2
NCT04551547 Sinovac Wang L, Nat Commun, 2022 New Full text Commentary Commentary	Inactivated virus	Coronavac 1.5mcg/boost Coronavac 1.5 mcg	Coronavac 3 mcg/boost Coronavac 3 mcg	RCT Phase 2	Children and adolescents aged 3-17 years without previous history of SARS-CoV-2 infection at a single center in China.	N= 346	Some concerns Details	Full description
TCTR20210720007 Pfizer/BioNTech+Fosun Pharma; AstraZeneca+University of Oxford ;Sinovac Niyomnaitham S, Hum Vaccin Immunother, 2022 a New Full text Commentary	Heterologous vaccination scheme	CoronaVac/ChAdOx1 CoronaVac/BNT162b2 ChAdOx1/CoronaVac ChAdOx1/BNT162b2 BNT162b2/CoronaVac BNT162b2+ChAdOx1	BNT162b2	RCT Phase 2	Adults including healthy or stable co-morbidities that were SARS-CoV-2 infection-free in a single centre in Thailand.	N= 210	Some concerns Details	Full description
N/A Sinocelltech Ltd. Hannawi S, J Infect, 2022 New Full text Commentary	Heterologous booster	BBIBP-CorV/Boost SCTV01C 20mcg BBIBP-CorV/Boost SCTV01C 40mcg	BBIBP-CorV/Boost Placebo	RCT Phase 1-2	Adults previously vaccinated with primary series of BBIBP-CorV with no history of COVID-19 in a single center in the United Arab Emirates.	N= 234	Some concerns Details	Full description
NCT04979949 Erciyes University and the Health Institutes of Turkey (TUSEB); Sinovac Omma A, Hum Vaccines Immunother, 2022 New Full text Commentary	Heterologous booster	CoronaVac/Boost TURKOVAC	CoronaVac/Boost CoronaVac	RCT Phase 2	Adults including healthy or stable co-morbidities with no recent history of COVID-19 in 4 centres in Turkiye.	N= 222	Some concerns Details	Full description
TCTR20210731003 AstraZeneca+University of Oxford/Sinopharm Tawinprai K, Expert Rev Vaccines, 2022 Full text Commentary	Heterologous booster	CoronaVac/Boost ChAdOx1	CoronaVac/Boost BBIBP-CorV	RCT Phase 2	Adults, including elderly, without active underlying disease and with no history of COVID-19, who completed 2 doses of CoronaVac, in a single centre in Thailand.	N= 81	Some concerns Details	Full description
NCT05188677 Sinovac/Clover Biopharmaceuticals Inc. Dynavax Rao C, medRxiv, 2022 Full text Commentary Commentary	Heterologous booster	CoronaVac/Boost SCB-2019	CoronaVac/Boost CoronaVac	RCT Phase 3	Adults who are healthy or have a stable pre-existing medical condition and SARS-CoV-2 infection-free in multiple centres in the Philippines.	N= 430	Some concerns Details	Full description
EudraCT, 2022-000063-51; NCT05249829 ModernaTX/ National Institute of Allergy and Infectious Diseases (NIAID) Lee I, medRxiv, 2023 a Full text Commentary Commentary	Heterologous booster	Any prime vaccine/Boost mRNA vaccine/ mRNA-1273.529	Any prime vaccine/Boost mRNA vaccine/ mRNA-1273	RCT Phase 2-3	Healthy or stable co-morbidities, at least 16 years who had previously received 2 injections of an authorized Covid-19 primary series vaccine with or without an mRNA-based booster as the third dose in 28 centres in UK.	N= 724	Some concerns Details	Full description
EudraCT, 2022-000063-51; NCT05249829 ModernaTX/National Institute of Allergy and Infectious Diseases (NIAID) Lee l, medRxiv, 2023 b Full text Commentary Commentary	Heterologous booster	Any prime vaccine/Boost mRNA vaccine/ mRNA-1273.214	Any prime vaccine/Boost mRNA vaccine/ mRNA-1273	RCT Phase 2-3	Healthy or stable co-morbidities, at least 16 years who had previously received 2 injections of an authorized Covid-19 primary series vaccine with or without an mRNA-based booster as the third dose in 28 centres in UK.	N= 2,824	Some concerns Details	Full description
NCT05289037 Pfizer/BioNTech+Fosun Pharma Branche A, Clin. Infect. Dis., 2023 COVAIL Full text Full text Full text Commentary Commentary Commentary	Heterologous booster	Any COVID-19 Vaccine/Boost any COVID-19 Vaccine/Boost BNT162b2 Omicron BA.1	Any COVID-19 Vaccine/Boost any COVID-19 Vaccine/Boost BNT162b2 Omicron BA.4/5	RCT Phase 2	Adults 18-49 who are healthy or have stable co-morbidities in 20 centres in the USA.	N= 202	Some concerns Details	Full description
NCT05057169 Sinovac Research and Development Co., Ltd; Pfizer/BioNTech + Fosun Pharma Leung N, medRxiv, 2022 Cobovax Full text Commentary Commentary	Heterologous booster	BNT162b2/Boost CoronaVac CoronaVac + boost BNT162b2	BNT162b2/boostBNT CoronaVac/Boost CoronaVac	RCT Phase 4	Adults including co-morbidities that were HIV-negative with no history of COVID-19 infection and who had previously completed CoronaVac or BNT162b2 primary schedules in multiple centres in Hong Kong (China).	N= 770	Some concerns Details	Full description

Akahata W, SSRN, 2023	Safety and Immunogenicity of SARS-CoV-2 Self-Amplifying RNA Vaccine Expressing Anchored RBD: A Randomised, Observer-Blind, Phase 1 Study
Al Kaabi N, Vaccines, 2023	Efficacy and Safety of a Booster Vaccination with Two Inactivated SARS-CoV-2 Vaccines on Symptomatic COVID-19 Infection in Adults: Results of a Double-Blind, Randomized, Placebo-Controlled, Phase 3 Trial in Abu Dhabi
Barda N, Clin Microbiol Infect, 2023	Immunogenicity of Omicron BA.1-adapted BNT162b2 vaccines; randomized trial, 3 months follow-up.
Estephan L,Vaccine	Safety and immunogenicity of homologous versus heterologous booster dose with AZD1222, mRNA-1273, or MVC-COV1901 SARS-CoV-2 vaccines in adults: An observer-blinded, multi-center, phase 2 randomized trial
Griessbach A, Open Forum Infect Dis, 2023	Antibody Response After Third Vaccination With mRNA-1273 or BNT162b2: Extension of a Randomized Controlled SARS-CoV-2 Noninferiority Vaccine Trial in Patients With Different Levels of Immunosuppression (COVERALL-2).
Hannawi S, J Infect, 2022	Safety and Immunogenicity of a Bivalent SARS-CoV-2 Protein Booster Vaccine, SCTV01C in Adults Previously Vaccinated with Inactivated Vaccine: a Randomized, Double-blind, Placebo-controlled Phase 1/2 Clinical Trial
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COVID-19 vaccine effectiveness(Randomized evidence)

Methods

meta-COVID

Vaccine types

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)