Pertussis over two decades: seroepidemiological study in a large population of the Siena Province, Tuscany Region, Central Italy.

Since 2002, approximately half of the population over 22 years of age have low IgG titres and are presumably susceptible to acquiring and transmitting pertussis infection. In addition, in 2013-2016, almost one-third of subjects aged 12-22 years, that is, the age group most likely to have been vaccinated against pertussis in infancy, had low antibody levels. Improving vaccination coverage and implementing careful surveillance are therefore recommended in order to prevent morbidity and mortality due to pertussis.