Table 3.
Comparative protective effectiveness of hybrid immunity relative to previous infection, vaccination, and hybrid immunity with fewer vaccine doses
| Exposure | Comparator | Number of studies | Number of estimates | Pooled relative protection (95% CI) | |
|---|---|---|---|---|---|
| Hybrid immunity vs previous infection | |||||
| Hospital admission or severe disease | Previous infection plus partial primary series vaccine | Previous infection | 2 | 3 | 28·9% (14·4–49·6) |
| Any infection | Previous infection plus partial primary series vaccine | Previous infection | 2 | 2 | 59·0% (51·5–66·1) |
| Hospital admission or severe disease | Previous infection plus full primary series | Previous infection | 3 | 4 | 57·7% (28·6–82·2) |
| Any infection | Previous infection plus full primary series | Previous infection | 4 | 5 | 46·1% (30·6–62·4) |
| Hospital admission or severe disease | Previous infection plus first booster dose | Previous infection | 3 | 3 | 80·1% (48·6–94·5) |
| Any infection | Previous infection plus first booster dose | Previous infection | 4 | 5 | 46·5% (24·6–69·9) |
| Hybrid immunity vs vaccination | |||||
| Any infection | Previous infection plus first booster dose | First booster dose | 1 | 1 | 88·9% (29·5–98·2) |
| Hybrid immunity vs hybrid immunity with fewer vaccine doses | |||||
| Hospital admission or severe disease | Previous infection plus full primary series | Previous infection plus partial primary series vaccine | 1 | 2 | 49·6% (19·9–79·7) |
| Any infection | Previous infection plus full primary series | Previous infection plus partial primary series vaccine | 1 | 1 | 16·3% (11·1–21·2) |
| Hospital admission or severe disease | Previous infection plus first booster dose | Previous infection plus partial primary series vaccine | 1 | 1 | 67·1% (21·1–86·3) |
| Any infection | Previous infection plus first booster dose | Previous infection plus partial primary series vaccine | 2 | 2 | 5·8% (0·2–65·2) |
| Hospital admission or severe disease | Previous infection plus first booster dose | Previous infection plus full primary series | 1 | 2 | 37·0% (6·2–83·9) |
| Any infection | Previous infection plus first booster dose | Previous infection plus full primary series | 3 | 3 | 40·8% (22·0–62·7) |
There were insufficient data available for a sensitivity analysis.