[Herd immunity and effectiveness of vaccination]

Abstract

The effectiveness of vaccinations is discussed in relation to vaccine efficacy and effectiveness of vaccination programs. The types of epidemiological studies used in the assessment of vaccine effectiveness are presented, and most common sources of bias in such studies are listed. Basic formulas for calculation of vaccine effectiveness are given as applied for cohort and case-control studies. The definitions and ways of estimation of indicators of herd immunity as applied to the analysis of the effectiveness of vaccinations are presented.