It has been suggested that the incidence of herpes zoster may increase due to lack of natural boosting under large-scale vaccination with the varicella vaccine. To study the possibility and magnitude of such negative consequences of mass vaccination, we built a mathematical model of varicella and zoster epidemiology in the Finnish population. The model was based on serological data on varicella infection, case-notification data on zoster, and new knowledge about close contacts relevant to transmission of infection. According to the analysis, a childhood programme against varicella will increase the incidence of zoster by one to more than two thirds in the next 50 years. This will be due to increase in case numbers in the 35 years age groups. However, high vaccine coverage and a two-dose programme will be very effective in stopping varicella transmission in the population.
(Accepted August 11 2009)
(Online publication October 02 2009)
c1 Author for correspondence: Dr K. Auranen, National Institute for Health and Welfare (THL), Department of Vaccination and Immune Protection, Mannerheimintie 166, FI-00300 Helsinki, Finland. (Email: email@example.com)