Studying the Herd Immunity Effect of the Varicella Vaccine in the Community of Valencia, Spain

摘要

In 2013, the Spanish Agency of Medicines blocked the varicella vaccine distribution based on a partial coverage of the vaccine that hypothetically could induce an increase of cases in adults: as non vaccinated children reach adulthood without having had contact with the virus in case the herd immunity stopped the virus circulation, or a hypothetical loss of vaccine protection in the long run. Also, this measure wanted to avoid increasing the number of cases of herpes zoster in adults. In this paper we develop a mathematical model to study the transmission dynamics of varicella in order to assess the impact of the partial coverage of the vaccination program. This is of paramount importance because, from the Public Health point of view, the herd immunity may be an undesirable effect of the partial vaccination due to that varicella and/or herpes zoster in adults use to be severe.