Each year enormous effort goes into producing influenza vaccines for that specific year and delivering them to appropriate sections of the population. Is this effort justified?
Public policy worldwide recommends the use of inactivated influenza vaccines to prevent seasonal outbreaks.
Because viral circulation and antigenic match vary each year and non-randomised studies predominate, systematic reviews of large datasets from several decades provide the best information on vaccine performance.
Evidence from systematic reviews shows that inactivated vaccines have little or no effect on the effects measured.
Most studies are of poor methodological quality and the impact of confounders is high.
Little comparative evidence exists on the safety of these vaccines.
Reasons for the current gap between policy and evidence are unclear, but given the huge resources involved, a re-evaluation should be urgently undertaken.