Fig. 4

Proportions of individuals with seroconversion. Overall and age-specific seroconversion proportions between study rounds (column) against different influenza A strains (row). Overall proportions are estimated by the proportion of seroconversoins that would have been obtained in each age group had the age distribution of study participant been perfectly representative to that of the general population. Vertical bars represent the 95% confidence intervals assuming the binomial distribution