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Table 4 Meta-analysis on primary outcome for adults and children

From: Natural attack rate of influenza in unvaccinated children and adults: a meta-regression analysis

Type of influenza # Influenza seasons Sample size (placebo group) # Influenza cases (placebo group) Natural attack rate % (lower 95% CI, upper 95% CI) I 2
Adults
All 19 28748 627 3.50 (2.30, 4.60) 98.0%
Influenza A 19 28748 482 2.32 (1.47, 3.17) 97.90%
Influenza B 19 28748 150 0.59 (0.28, 0.91) 98.11%
Children
All 13 6187 1040 15.20 (11.40, 18.90) 94.0%
Influenza A 10 5432 714 12.27 (8.56, 15.97) 94.59%
Influenza B 11 5926 341 5.50 (3.49, 7.51) 94.69%
  1. Abbreviations: CI confidence interval.