Vaccine Induced Protection Against Influenza: Persistence of Serum Antibodies, Vaccine Efficacy as a Function of Time, and Use of Transmission Models to Estimate Vaccine Effectiveness in Household Cohort Studies.

Abstract

Influenza vaccine is currently the best available means of preventing influenza infection, though vaccine effectiveness can vary year to year based on factors such as match between circulating viruses and those included in the vaccine. We studied additional sources of variation in vaccine effectiveness estimates, both biological and methodological, including duration of vaccine induced protection, and model choice in household cohort studies. Duration of protection was examined by quantifying the persistence of serum antibodies and by estimating vaccine efficacy as a function of time. We also extended a model specifying household structure and within-household transmission, and compared influenza vaccine effectiveness estimates to those from Cox-proportional hazards models.