The efficacy of polio vaccination in Finland.

The inactivated polio vaccine has eliminated not only the disease but also polioviruses from Finland. The last endemic cases of poliomyelitis were seen in 1961, and two were imported in 1964. To check whether polioviruses were still circulating in Finland, an intensified search for polioviruses was carried out in 1972-1974 in sewage, among patients with polio-like diseases and among healthy preschool children. Viruses, mostly Coxsackie B viruses, were isolated from sewage in 67% of the samples, but no polioviruses. The etiology of aseptic meningitis and other polio-like diseases was explained in 52% of the cases, but without isolation of any polioviruses. Faeces samples from 4878 different preschool children were examined: 15.7% of them excreted viruses, but not polioviruses.