Table 7.
The effectiveness of booster immunization of COVID-19 vaccines to prevent SARS-CoV-2 infection and COVID-19 caused by Omicron variants*.
| Type of disease | Variant | No. of studies | RR/OR (95% CI) | P h/I 2 (%) & | VE (%) (95% CI) # | P | Vaccine name |
|---|---|---|---|---|---|---|---|
| Omicron variant (B.1.1.529) | |||||||
|
Cohort studies：
SARS-CoV-2 infection |
Overall | 6 | 0.361 (0.212, 0.624) | <0.001/99.4 | 63.9 (37.6, 78.8) | <0.001 | |
| RNA-based vaccine | 4 | 0.313 (0.169, 0.578) | <0.001/93.2 | 68.7 (42.2, 83.1) | <0.001 | BNT16b2; mRNA-1273 | |
| Severe COVID-19 | Overall | 4 | 0.151 (0.123, 0.185) | <0.001/88.5 | 84.9 (81.5, 87.7) | <0.001 | |
| RNA-based vaccine | 2 | 0.147 (0.099, 0.219) | <0.001/92.6 | 85.3 (78.1, 90.1) | <0.001 | BNT16b2; mRNA-1273 | |
| COVID-19-related death | Overall | 2 | 0.046 (0.003, 0.782) | <0.001/94.0 | 95.4 (20.8, 99.7) | <0.001 | |
|
Case–control studies：
SARS-CoV-2 infection |
Overall | 3 | 0.393 (0.291, 0.532) | <0.001/96.7 | 60.7 (46.8, 70.9) | <0.001 | |
| RNA-based vaccine | 2 | 0.351 (0.258, 0.477) | <0.001/98.2 | 64.9 (52.3, 74.2) | <0.001 | BNT16b2; mRNA-1273 | |
| Symptomatic COVID-19 | Overall | 9 | 0.352 (0.311, 0.393) | <0.001/92.7 | 64.8 (60.7, 68.9) | <0.001 | BNT16b2; mRNA-1273 |
| Severe COVID-19 | Overall | 7 | 0.093 (0.058, 0.138) | 0.053/51.8 | 90.7 (86.2, 94.2) | <0.001 | |
| RNA-based vaccine | 6 | 0.081 (0.052, 0.133) | 0.036/58.1 | 91.9 (86.7, 94.8) | <0.001 | BNT162b2, mRNA-1273 | |
| COVID-19-related death | RNA-based vaccine | 1 | 0.060 (0.020, 0.150) | NA | 94.0 (85.0, 98.0) | <0.001 | BNT162b2, mRNA-1273 |
| Omicron variant (BA.2) | |||||||
| Cohort studies: Symptomatic COVID-19 |
Overall | 4 | 0.393 (0.281, 0.554) | 0.238/29.1 | 60.7 (44.6, 71.9) | <0.001 | |
| RNA-based vaccine | 2 | 0.282 (0.178, 0.437) | 1.00/0.0 | 71.8 (56.3, 82.2) | <0.001 | BNT16b2; mRNA-1273 | |
| Inactivated virus | 2 | 0.512 (0.354, 0.743) | 0.837/0.0 | 48.8 (25.7, 64.6) | <0.001 | CoronaVac | |
| Severe COVID-19 | Overall | 4 | 0.023 (0.014, 0.037) | 0.138/46.0 | 97.7 (96.3, 98.6) | <0.001 | |
| RNA-based vaccine | 2 | 0.027 (0.014, 0.052) | 0.180/44.3 | 97.3 (94.8, 98.6) | <0.001 | BNT16b2 | |
| Inactivated virus | 2 | 0.022 (0.007, 0.045) | 0.074/68.7 | 97.8 (95.5, 99.3) | <0.001 | CoronaVac | |
| COVID-19-related death | Overall | 6 | 0.017 (0.009, 0.032) | 0.415/0.2 | 98.3 (96.8, 99.1) | <0.001 | |
| RNA-based vaccine | 3 | 0.017 (0.005, 0.052) | 0.136/49.8 | 98.3 (94.8, 99.5) | <0.001 | BNT16b2 | |
| Inactivated virus | 3 | 0.014 (0.005, 0.039) | 0.707/0.0 | 98.6 (96.1, 99.5) | <0.001 | CoronaVac | |
*Comparison between booster vaccinees and unvaccinated group; #Vaccine effectiveness = 100*(1–RR) % or 100*(1–OR) %; & NA, not available.