Table 2.
Summary of meta-analyses* of vaccine effectiveness for two consecutive seasons' vaccination history and influenza type or subtype
| Current season | Previous season | Current and previous season | ΔVEc† | ΔVEp† | |
|---|---|---|---|---|---|
| A(H1N1)pdm09 | 58% (48 to 66) | 33% (21 to 43) | 53% (44 to 60) | −9% (−16 to −1) | 21% (11 to 30) |
| A(H3N2) | 37% (29 to 45%) | 9% (−3 to 19) | 20% (12 to 27) | −18% (−26 to −11) | 7% (−4 to 18) |
| B | 54% (49 to 59) | 21% (12 to 29) | 47% (41 to 53) | −7% (−14 to 0) | 25% (16 to 34) |
| B infection and B/Victoria in TIV | 47% (38 to 55) | 19% (6 to 31) | 45% (35 to 54) | −2% (−13 to 9) | 26% (11 to 40) |
| B infection and B/Yamagata in TIV | 61% (54 to 67) | 23% (11 to 34) | 48% (39 to 55) | −10% (−19 to −2) | 24% (12 to 37) |
| B-Victoria infection | 61% (43 to 73) | 31% (0 to 53) | 52% (38 to 63) | −10% (−31 to 12) | 15% (−10 to 41) |
| B-Yamagata infection | 56% (39 to 68) | 38% (25 to 49) | 52% (42 to 60) | −5% (−17 to 6) | 14 (0 to 28) |
Data are vaccine effectiveness estimates (95% CI). TIV=trivalent influenza vaccine. VE=vaccine effectiveness.
*
Random effect model results shown; for fixed effect estimates refer to the appendix (pp 41–55).
†
ΔVE>0 implies higher vaccine effective estimate when vaccinated in current and previous seasons compared with the current (VEC) or previous (VEP) season only.