Comparison of multiple estimates of efficacy for influenza vaccine

Influenza vaccine trials typically report vaccine efficacy for infection-confirmed symptomatic illness. Data on indirect vaccine efficacy for susceptibility, the degree of vaccine protection to susceptibles, or indirect vaccine efficacy for illness given infection, are sparse. Using inactivated influenza vaccine randomized trial data, we calculated indirect vaccine efficacy for susceptibility of 20% [95% CI 9-30] and indirect vaccine efficacy …