Table 4.
Comparison of vaccine effectiveness according to several factors observed in TND studies. (95% confidence intervals are presented in brackets; a p-value lower than 0.05 or 0.01 is identified with * or **; a comparison between studies that only use the TIV vaccine and the other; b comparison between studies where vaccine and circulating strains match and mismatch, only for TIV studies; c comparison between studies that only use the QIV vaccine and the other; d comparison between studies that only use the LAIV vaccine and the other, e comparison between studies where vaccine and circulating strains match and mismatch, all studies; f comparison between studies that include individuals with severe symptoms and those that do not; g comparison between studies that include inpatient individuals and those that do not; h comparison between studies that confirm the presence of the influenza virus using only PCR and those that do not).
| Yes | No | p-Value | (%) | |
|---|---|---|---|---|
| Adjusted estimate? | 39.9 (30.5–47.9) | 41.0 (36.8–44.9) | 0.419 | 77.9 |
| TIV? a | 44.9 (39.1–50.1) | 30.3 (22.0–37.7) | 0.010 * | 76.9 |
| Match circulating strains, TIV? b | 48.3 (41.7–54.2) | 40.1 (29.1–49.4) | 0.080 | 61.4 |
| QIV? c | 34.3 (29.6–38.7) | 42.7 (36.4–48.3) | 0.454 | 80.8 |
| LAIV? d | 5.4 (−20.7–25.9) | 41.4 (37.1–45.4) | 0.001 ** | 78.5 |
| Match circulating strains? e | 45.1 (38.7–50.8) | 35.1 (29.0–40.7) | 0.017 * | 69.8 |
| Not only ILI? f | 38.7 (33.5–43.5) | 43.9 (37.7–49.5) | 0.176 | 73.9 |
| Not only outpatients? g | 43.1 (33.2–51.6) | 39.6 (35.1–43.8) | 0.497 | 80.3 |
| Only PCR? h | 42.7 (38.3–46.8) | 29.7 (20.4–37.9) | 0.012 * | 76.3 |
| Northern Hemisphere? | 39.1 (34.4–43.4) | 44.7 (36.1–52.2) | 0.196 | 80.2 |