Immunization with oral poliovirus vaccine in China

China began to produce oral, live poliovirus vaccine ( OPV ) in 1960. During 1960-1964, OPV was introduced in major cities only and subsequently was used throughout the country. Since that time the incidence of poliomyelitis has dropped dramatically, and the percentage of the healthy population with antibody has clearly risen. Data from many observations showed a high rate of isolation of other enteroviruses in the healthy population and in individuals with poliomyelitis. These findings indicate that some paralytic cases may be caused by other enteroviruses. Localized outbreaks of poliomyelitis still occur, however, and their elimination will require a campaign to ensure that greater than 90% of susceptible individuals are immunized.