Table 2.
The effectiveness of COVID-19 vaccines to prevent SARS-CoV-2 Delta variant infection.
| Variant | No. of studies | Adjust OR (95% CI) | P h/I 2 (%) & | VE (%) (95% CI)# | P | Vaccine name |
|---|---|---|---|---|---|---|
| Case–control studies | ||||||
| To prevent SARS-CoV-2 infection | ||||||
| Overall | 25 | 0.205 (0.161, 0.262) | <0.001/99.1 | 79.5 (73.9, 83.8) | <0.001 | |
| RNA-based vaccine | 14 | 0.179 (0.119, 0.269) | <0.001/99.4 | 82.1 (73.1, 88.1) | <0.001 | BNT162b2; mRNA-1273 |
| Viral vector (non-replicating) | 6 | 0.316 (0.274, 0.366) | 0.002/73.2 | 68.4 (63.4, 72.6) | <0.001 | ChAdOx1 nCoV-19 |
| Inactivated virus | 1 | 0.401 (0.312, 0.513) | NA | 59.9 (48.7, 68.8) | <0.001 | CoronaVac |
| To prevent asymptomatic SARS-CoV-2 infection | ||||||
| Overall | 3 | 0.527 (0.457, 0.608) | 0.735/0.0 | 47.3 (39.2, 54.3) | <0.001 | BNT162b2; mRNA-1273 |
| To prevent symptomatic COVID-19 | ||||||
| Overall | 19 | 0.198 (0.151, 0.259) | <0.001/99.0 | 80.2 (74.1, 84.9) | <0.001 | |
| RNA-based vaccine | 13 | 0.159 (0.112, 0.226) | <0.001/98.5 | 84.1 (77.4, 88.8) | <0.001 | BNT162b2; mRNA-1273 |
| Viral vector (non-replicating) | 5 | 0.342 (0.269, 0.431) | <0.001/91.5 | 65.8 (56.9, 73.1) | <0.001 | ChAdOx1 nCoV-19 |
| Inactivated virus | 1 | 0.412 (0.195, 0.862) | NA | 58.8 (13.8, 81.5) | 0.019 | CoronaVac; HB02; WIV04 |
| 12 to 17 years old | 2 | 0.086 (0.048, 0.151) | 0.104/62.1 | 91.4 (84.9, 95.2) | <0.001 | BNT162b2 |
| ≥ 65 years old | 1 | 0.332 (0.297, 0.366) | NA | 66.8 (63.4, 70.3) | <0.001 | BNT162b2 |
| To prevent severe COVID-19 | ||||||
| Overall | 25 | 0.049 (0.035, 0.069) | <0.001/95.8 | 95.1 (93.1, 96.5) | <0.001 | |
| RNA-based vaccine | 18 | 0.046 (0.031, 0.070) | <0.001/96.7 | 95.4 (93.0, 96.9) | <0.001 | BNT162b2; mRNA-1273 |
| Viral vector (non-replicating) | 5 | 0.097 (0.071, 0.132) | 0.223/29.8 | 90.3 (86.8, 92.9) | <0.001 | ChAdOx1 nCoV-19 |
| 12 to 18 years old | 1 | 0.077 (0.054, 0.119) | NA | 92.3 (88.1, 94.6) | <0.001 | BNT162b2 |
| ≥ 65 years old | 2 | 0.108 (0.035, 0.334) | <0.001/97.0 | 89.2 (66.6, 96.5) | <0.001 | BNT162b2, mRNA-1273 |
| To prevent COVID-19-related death | ||||||
| Overall | 3 | 0.076 (0.051, 0.114) | 0.198/38.2 | 92.4 (88.6, 94.9) | <0.001 | |
| RNA-based vaccine | 2 | 0.062 (0.043, 0.089) | 0.737/0.0 | 93.8 (91.1, 95.7) | <0.001 | BNT162b2; mRNA-1273 |
| Viral vector (non-replicating) | 1 | 0.11 (0.07, 0.20) | NA | 89.0 (80.0, 93.0) | <0.001 | ChAdOx1 nCoV-19 |
| Cohort studies | ||||||
| To prevent SARS-CoV-2 infection | ||||||
| Overall | 25 | 0.286 (0.252, 0.324) | <0.001/96.9 | 71.4 (67.6, 74.8) | <0.001 | |
| RNA-based vaccine | 16 | 0.254 (0.211, 0.307) | <0.001/97.5 | 74.6 (69.3, 78.9) | <0.001 | BNT162b2; mRNA-1273 |
| Viral vector (non-replicating) | 3 | 0.497 (0.396, 0.624) | 0.410/0.0 | 50.3 (37.6, 60.4) | <0.001 | ChAdOx1 nCoV-19; Ad26.COV2.S |
| Inactivated virus | 1 | 0.482 (0.163, 0.786) | NA | 51.8 (19.4, 83.7) | 0.0391 | HB02; WIV04; CoronaVac |
| 12-18 years old | 4 | 0.128 (0.092, 0.177) | 0.012/72.7 | 87.2 (82.3, 90.8) | <0.001 | BNT162b2 |
| 60-79 years old | 1 | 0.441 (0.393, 0.492) | NA | 55.9 (50.8, 60.7) | <0.001 | BNT162b2; mRNA-1273 |
| ≥ 80 years old | 1 | 0.652 (0.514, 0.828) | NA | 34.8 (17.2, 48.6) | 0.001 | BNT162b2; mRNA-1273 |
| To prevent symptomatic COVID-19 | ||||||
| Overall | 3 | 0.162 (0.056, 0.458) | 0.011/77.8 | 83.8 (54.2, 94.4) | 0.001 | |
| RNA-based vaccine | 2 | 0.098 (0.044, 0.216) | 0.182/43.9 | 90.2 (78.4, 95.6) | <0.001 | BNT162b2; mRNA-1273 |
| Inactivated virus | 1 | 0.403 (0.112, 0.684) | NA | 59.7 (31.6, 88.8) | 0.035 | CoronaVac; HB02; WIV04 |
| To prevent severe COVID-19 | ||||||
| Overall | 6 | 0.103 (0.066, 0.163) | <0.001/98.8 | 89.7 (83.7, 93.4) | <0.001 | |
| RNA-based vaccine | 4 | 0.085 (0.054, 0.134) | <0.001/96.0 | 90.5 (86.6, 94.6) | <0.001 | BNT162b2; mRNA-1273 |
| ≥ 80 years old | 1 | 0.228 (0.176, 0.314) | NA | 77.2 (68.6, 82.4) | <0.001 | BNT162b2; mRNA-1273 |
| To prevent COVID-19-related death | ||||||
| Overall | 3 | 0.167 (0.075, 0.370) | <0.001/97.5 | 83.3 (63.0, 92.5) | <0.001 | BNT162b2, mRNA-1273, Ad26.COV2.S et al. |
#Vaccine effectiveness = 100*(1–RR/OR) %.
&NA, not available.