Table 3. Direct meta-analyses comparing the immunogenicity (rates of seroconversion *) of adjuvanted versus non-adjuvanted H1N1 influenza vaccines.
| Adjuvanted vs Non-adjuvanted, by age | Adults 1 | Elderly 2 | Adolescents 3 | Children 4 | All ages | ||||
| RR (95%CI) | N (ref.) | RR (95%CI) | N (ref.) | RR (95%CI) | N (ref.) | RR (95%CI) | N (ref.) | RR (95%CI) | |
| 7.5 (1 dose only) | 0.84 (0.73–0.98) | 607 [12], [19] | 0.72 (0.60–0.86) | 255 [19] Al | 0.83 (0.77–0.89) | 421 [19] Al | 0.73 (0.63–0.84) | 430 [19] Al | 0.80 (0.74–0.86) |
| 0.81 (0.74–0.89) | 531 [19] Al | ||||||||
| 0.98 (0.72–1.33) | 76 [12] Sq | ||||||||
| 15 (1 dose only) | 1.18 (0.62–2.26) | 1532 [12], [19] | 0.89 (0.79–1.00) | 950 [19] Al | 0.93 (0.88–0.98) | 1295 [19] Al | 0.90 (0.82–0.98) | 1313 [19] Al | 0.92 (0.86–0.98) |
| 0.88 (0.83–0.94) | 1482 [19] Al | ||||||||
| 1.69 (1.13–2.53) | 50 [12] Sq | ||||||||
| All doses, by age ** (1 dose only) | 1.00 (0.88–1.14) | 3362 [12], [19], [39] | 0.83 (0.75–0.92) | 1992 [19] Al | 0.91 (0.84–0.99) | 2684 [19] Al | 0.82 (0.67–1.00) | 1743 [19] Al | 0.90 (0.85–0.95) |
| 0.88 (0.81–0.95) | 3109 [19] Al | ||||||||
| 1.28 (0.99–1.67) | 253 [12], [39] Sq | ||||||||
| 7.5 (2 doses) | 0.97 (0.69–1.35) | 556 [12], [19] | 0.98 (0.89–1.08) | 240 [19] Al | 0.89 (0.85–0.94) | 387 [19] Al | 0.95 (0.91–0.99) | 415 [19] Al | 0.92 (0.86–0.99) |
| 0.83 (0.78–0.89) | 509 [19] Al | ||||||||
| 1.17 (0.92–1.50) | 49 [12] Sq | ||||||||
| 15 (2 doses) | 0.98 (0.94–1.02) | 1321 [19] Al | 0.89 (0.81–0.96) | 812 [19] Al | 0.95 (0.92–0.99) | 1100 [19] Al | 0.99 (0.96–1.01) | 1165 [19] Al | 0.96 (0.93–1.00) |
| All doses, by age ** (2 doses) | 1.01 (0.91–1.12) | 2957 [12], [19], [39] | 0.95 (0.88–1.03) | 1711 [19] Al | 0.95 (0.89–1.02) | 2294 [19] Al | 0.97 (0.94–1.01) | 1580 [19] Al | 0.97 (0.93–1.00) |
| 0.95 (0.82–1.10) | 2783 [19] Al | ||||||||
| 1.17 (1.06–1.28) | 174 [12], [39] Sq | ||||||||
Only randomized trials were included. All doses are in µg. N = total number of subject analyzed; (ref) = References to included studies; RR = Random-effect risk ratio; CI = Confidence Intervals; Ad = Adjuvant.
Adults = from 18 to 64 years;
Elderly = from 65 years;
Adolescents = from 10 to 17 years;
Children = from 6 months to 9 years (see Table S1 for several exceptions).
*Seroconversion = subjects with a pre-vaccination hemagglutinination-inhibition antibody titer < = 1∶10 and a post-vaccination titer > = 1∶40, or a pre-vaccination titer > = 1∶10 and an increase in the titer by a factor of four or more after vaccination.
**The total sample of overall meta-analyses may be lower (higher) than the sum of stratified meta-analyses because some arms had to be split to be included in more than a stratified meta-analysis (some arms were different from the main comparisons shown in the Table); in any case, no subject was counted twice. Al = Only aluminum adjuvants; Sq = Only squalene-based (oil-in-water) adjuvants.