Mass Vaccination Against Poliomyelitis in Mexico

In 1959, oral poliovirus vaccine ( OPV ) was introduced as an antiepidemic measure in Mexico. As in many other developing countries, the vaccine was misused, coverages achieved were often poor, and an adequate cold chain was lacking. However, in 1972 a mass campaign reached 70% of children younger than five years of age, and consequently the reported cases declined sharply from 1.9 to 0.4 per 100,000 population. Due to economic restrictions, only single doses of monovalent type 1 OPV were administered to 80% of the target population in 1981, 1982, and 1983. The present incidence of poliomyelitis of 0.1 per 100,000 population represents a 96.7% reduction from the rate during the prevaccine era, when the annual average rate was 4.26 per 100,000. The present aim of poliomyelitis control is to maintain and decrease the present incidence of disease. Future plans are to continue mass vaccination in an attempt to reach small and isolated villages that have been without vaccination and limit possible rural foci of wild poliovirus.