Serum antibodies to poliomyelitis in Italy.

A seroepidemiological survey was conducted to assess the effectiveness of the Italian nationwide immunization programme against poliomyelitis. Over 3800 serum samples were collected from persons, aged between 6 months and 79 years and residing in urban and rural areas with different socioeconomic conditions and geographic locations.A very high level of protection was found in the target population, confirming the almost 100% history of complete immunization. Almost all subjects over 30 years of age were found to have poliovirus antibodies, although they had never been vaccinated. In Naples, a higher proportion of subjects susceptible to all 3 types of virus was found in the age group 6-23 months, suggesting a delay in the administration of vaccine. This was confirmed by the analysis of the immunization history. No difference was observed between urban and rural areas, in either serological results or history of immunization.The results confirmed the higher immunogenicity of poliovirus type 2 with respect to the other two types, the effectiveness of the vaccine, and, finally, the efficiency of the operational procedures adopted for its administration.