[The concept of herd immunity applied to the evaluation of vaccination programs].
The article concerns the definition and ways of estimation of indicators of herd immunity as applied to the analysis of the efficiency of vaccination programmes. Some important factors are discussed which determine the proportion of vaccinated individuals in the population necessary for decrease of incidence and eventually for elimination of the disease from a population. The problems related to definition and calculation of herd immunity in populations non uniform in terms of individual risk of infection are discussed.