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.
A list of studies pending extraction is available here.
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)
- Immunogenicity
Geometric mean titre specific antibodiesReference Type of prime vaccination Prime schedule Intervention 1 Intervention 2 Follow up
daysParticipants GMT1(N1) GMT2(N2) GMR [95% CI] Evaluated by Risk of bias 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
Geometric mean titre neutralization assay against -wild typeReference Type of prime vaccination Prime schedule Intervention 1 Intervention 2 Follow up
daysParticipants 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)
Geometric mean titre neutralization assay- omicronReference Type of prime vaccination Prime schedule Intervention 1 Intervention 2 Follow up
daysParticipants 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) Munro A, 2021 d RNA based vaccine BNT162b2 Boost BNT162b2 Placebo 28 Adults, elderly, health care workers 0
(95)0
(93)NR NR Munro A, 2021 d RNA based vaccine BNT162b2 Boost VLA2001 Placebo 28 Adults, elderly, health care workers 0
(91)0
(93)NR NR Munro A, 2021 d RNA based vaccine BNT162b2 Boost VLA2001 half dose Placebo 28 Adults, elderly, health care workers 0
(87)0
(93)NR NR Munro A, 2021 d RNA based vaccine BNT162b2 Boost Ad26.COV2.S Placebo 28 Adults, elderly, health care workers 0
(75)0
(93)NR NR Thuluva S, 2023 a Non replicating viral vector ChAdOx1 Boost BECOV2 Boost Placebo 28 Adults 79
(156)0
(52)NR Pseudovirus Neutralization Assay (PNA) - Safety
Serious adverse eventsReference Type of prime vaccination Prime schedule Intervention 1 Intervention 2 Follow up
monthsParticipants 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
All-cause mortalityReference Type of prime vaccination Prime schedule Intervention 1 Intervention 2 Follow up
monthsParticipants 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 Thuluva S, 2023 a Non replicating viral vector ChAdOx1 Boost BECOV2 Boost Placebo 6 Adults 0 / 156 0 / 52 NR
Vaccine efficacy, immunogenicity and safety of booster VS booster (tables)
- Immunogenicity
Geometric mean titre specific antibodiesReference Type of prime vaccination Prime schedule Intervention 1 Intervention 2 Follow up
daysParticipants GMT Boost1 (N1) GMT Boost2 (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 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 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 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 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 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 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 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 neutralization assay against -wild typeReference Type of prime vaccination Prime schedule Intervention 1 Intervention 2 Follow up
daysParticipants GMT Boost1 (N1) GMT Boost2 (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 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) 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 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) 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 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 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 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 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 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 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 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 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 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 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) 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) 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- omicronReference Type of prime vaccination Prime schedule Intervention 1 Intervention 2 Follow up
daysParticipants GMT Boost1 (N1) GMT Boost2 (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 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. 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) 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) 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 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 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 Adolescents 0
(*)0
(*)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 Adolescents 0
(*)0
(*)NR NR Rose W, 2023 Non replicating viral vector ChAdOx1 Boost BBV152 Boost ChAdOx1 Adults 0
(*)0
(*)NR NR Rose W, 2023 Inactivated virus BBV152 Boost ChAdOx1 Boost BBV152 Adults 0
(*)0
(*)NR NR 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 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 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) 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 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 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 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 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 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 - Safety
Serious adverse eventsReference Type of prime vaccination Prime schedule Intervention 1 Intervention 2 Follow up
monthsParticipants 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 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]Al Kaabi N, 2023 Inactivated virus BBIBP-CorV Boost NVSI-06-09 Boost BBIBP-CorV 1 Healthy adults 0 / 260 0 / 256 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 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 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 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]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]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 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]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 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 Natori Y, 2023 RNA based vaccine BNT162b2 Boost Ad26.COV2.S Boost BNT162b2 1 Transplant recipients 0 / 28 0 / 30 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 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 Toback S, 2023 Inactivated virus BBIBP-CorV Boost NVX-CoV2373 Boost BBIBP-CorV 1 Healthy volunteers 0 / 497 0 / 501 NR
All-cause mortalityReference Type of prime vaccination Prime schedule Intervention 1 Intervention 2 Follow up
monthsParticipants r1/N1 r2/N2 RR [95% CI] Risk of bias A B C D E Overall 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 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 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 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 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 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 Corominas J, 2023 RNA based vaccine BNT162b2 Boost PHH-1V Boost BNT162b2 3.2 Healthy adults 0 / 513 0 / 252 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 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 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 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 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
COVID-19 PRIME VACCINATION: Last search date December 14, 2022.
Vaccine efficacy and safety for vaccine vs placebo / no vaccine (forest plots)
Overall efficacy and safety of all vaccines vs placebo - Charts (Last update:2022-04-14)
- Forest plots (last update: 2021-11-19)
- Studies included
- Forest plots (last update: 2023-03-07)
- Studies included
- Forest plots (last update: 2022-11-04)
- Studies included
- Forest plots (last update: 2022-10-06)
- Studies included
- Forest plots (last update: 2023-01-06)
- Studies included
- Forest plots (last update: 2022-07-07)
- Studies included
- Forest plots (last update: 2022-08-04)
- Studies included
Vaccine effectiveness over time
RNA based vaccine
Non replicating viral vector
Inactivated virus
Protein subunit
Virus-Like particle
DNA based vaccine
Vaccine efficacy and safety for vaccine vs vaccine (forest plots)
- BECOV2 vs ChAdOx1 - Forest plots (last update: 2022-06-25)
- BNT162b2 vs mRNA-1273 - Forest plots (last update: 2022-11-18)
- MVC-COV1901 vs ChAdOx1 - Forest plots (last update: 2022-10-06)
- SII-ChAdOx1 nCoV-19 vs ChAdOx1 - Forest plots (last update: 2021-11-26)
- TURKOVAC vs CoronaVac - Forest plots (last update: 2023-01-06)
- VLA2001 vs ChAdOx1 - Forest plots (last update: 2022-11-04)
Vaccine efficacy, immunogenicity and safety of heterologous vs homologous vaccination (tables)
- Efficacy
Severe or critical COVID-19 after complete vaccinationReference Intervention 1 Intervention 2 Follow up
monthsParticipants r1/N1 r2/N2 RR [95% CI] Risk of bias A B C D E Overall Toledo-Romani ME, 2022 b FINLAY-FR-2-25 mcg +FR-1-50 mcg Placebo * Adults 0 / 13828 6 / 12486 100.0
[*, 100]
Confirmed symptomatic COVID-19 after complete vaccinationReference Intervention 1 Intervention 2 Follow up
monthsParticipants r1/N1 r2/N2 VE [95% CI] Risk of bias A B C D E Overall Toledo-Romani ME, 2022 b FINLAY-FR-2-25 mcg +FR-1-50 mcg Placebo * Adults NR NR 92.0
[80.4, 96.7] - Immunogenicity
Geometric mean titre specific antibodiesReference Intervention 1 Intervention 2 Follow up
daysParticipants 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
Geometric mean titre neutralizing antibodiesReference Intervention 1 Intervention 2 Follow up
daysParticipants 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 - Safety
Serious adverse eventsReference Intervention 1 Intervention 2 Follow up
monthsParticipants 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 Toledo-Romani ME, 2022 b FINLAY-FR-2-25 mcg +FR-1-50 mcg Placebo 2.7 Adults 1 / 14677 3 / 14675 0.33
[0.03 - 3.2]
All-cause mortalityReference Intervention 1 Intervention 2 Follow up
monthsParticipants 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 Toledo-Romani ME, 2022 b FINLAY-FR-2-25 mcg +FR-1-50 mcg Placebo 5.4 Adults 11 / 13883 24 / 14303 0.47
[0.23 - 0.96]
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 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
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 |
RCTPhase 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 |
|
CTRI/2022/01/039366 Biological E Limited Thuluva S, medRxiv, 2023 b Full text Commentary |
Protein subunit |
BBV152/Boost BECOV2 |
BBV152/Boost Placebo |
RCTPhase 3 | Adults including elderly and co-morbidities in 7 centres in India. | N= 208 |
Low Details |
|
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 |
RCTPhase 3 | Healthy adults with no history of COVID-19 in multiple centres in China. | N= 420 |
Some concerns Details |
|
CTRI/2022/04/042017 Novavax Kulkarni P, Research Square, 2023 a Full text Commentary |
Heterologous booster |
ChAdOx1/Boost SII-NVX-CoV2373 |
ChAdOx1 /Boost ChAdOx1 |
RCTPhase 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 |
|
CTRI/2022/01/039366 Biological E Limited Thuluva S, medRxiv, 2023 a Full text Commentary |
Heterologous vaccination scheme |
ChAdOx1/Boost BECOV2 |
ChadOx1/boostPlacebo |
RCTPhase 3 | Adults including elderly and co-morbidities in 7 centres in India. | N= 208 |
Low Details |
|
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 |
RCTPhase 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 |
|
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 |
RCTPhase 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 |
|
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 |
RCTPhase 1 | Healthy adults, ≥65 years years of age, SARS-CoV-2 infection-free in a single centre in Japan. | N= 46 |
Some concerns Details |
|
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 |
RCTPhase 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 |
|
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 |
RCTPhase 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 |