Table 2.
Characteristics of included studies on the efficacy of COVID-19 vaccines.
| Study | Vaccine | Administration (no. of doses, intervals, dosage) | Age range | No. of participants (vaccination/control) | Country | Study types (phase, no. of centers, blinding) | Vaccine efficacy(95% CI) |
|---|---|---|---|---|---|---|---|
| Bravo 2022 (50) | SCB-2019 | 2, 21 d, 30 µg | ≥ 65 | 121/127 | Belgium, Brazil, Colombia, Philippines, South Africa | II/III, 31, double-blind | 58.4% (−73.4, 92.9)† |
| Ella 2021* (53) | BBV152 vaccine | 2, 28 d, 6 µg | ≥ 60 | 893/965 | Indian | III, 25, double-blind | 67.8% (8.0, 90.0) |
| Falsey 2021 (54) | ChAdOx1-S- (AZD1222) | 2, 28 d, 5 × 1010 VP | ≥ 65 | 3696/1812 | the United States, Chile, Peru | III, 88, double-blind | 83.5% (54.2, 94.1) |
| Halperin 2022 (57) | Ad5-nCoV | 1, −, 5 × 1010 VP | ≥ 60 | 1323/1347 | Pakistan, Mexico, Russia, Chile, Argentina | III, 66, double-blind | 53.3% (0.9, 78.0) |
| Heath 2021 (59) | NVX-CoV 2373 |
2, 21 d, 5 µg | ≥ 65 | 1953/1957 | the UK | III, 33, observer-blinded | 88.9% (12.8, 98.6) |
| Logunov 2021* (64) | Gam-COVID-Vac | 2, 21 d, 1 × 1011 VP | > 60 | 1611/533 | Russia | III, 25, double-blind | 91.8% (67.1, 98.3) |
| Sadoff 2022 (70) | Ad26.COV2.S | 1, −, 5 × 1010 VP | ≥ 60 | 6735/6724 | Latin America, Argentina, Brazil, Chile, Colombia, Mexico, Peru, South Africa, the United States | III, 8, double-blind | 55.0% (42.9, 64.7)† |
| Sahly 2021 (71) | mRNA-1273 | 2, 28 d, 100 µg | ≥ 65 | 3626/3595 | the United States | III, 99, observer-blinded | 91.5% (83.2, 95.7) |
| Thomas 2021 (73) | BNT162b2 | 2, 21 d, 30 µg | ≥ 55 | 8194/8208 | the United States, Argentina, Brazil, Germany, South Africa, Turkey | II/III, 152, observer-blinded | 90.9% (86.3, 94.2)† |
Vp, viral particles. The vaccine efficacy (with 95% confidence intervals) in this table was based on what was reported in the original literature. †Indicated that the vaccine efficacy in the original literature was calculated on person-years, the total time for the given endpoint across all participants at risk within each group. *Indicated that the vaccine efficacy in the original literature was calculated based on symptomatic cases of COVID-19.