Use of surveillance data to estimate the effectiveness of the 7-valent conjugate pneumococcal vaccine in children less than 5 years of age over a 9 year period

► The indirect cohort method appears suitable for estimating pneumococcal conjugate vaccine effectiveness. ► An indirect cohort design confirms the findings of the case-control study. ► This method would be most useful shortly after vaccine introduction. ► The method is less useful in a setting of high vaccine coverage and few vaccine-type cases.