Combined live and inactivated poliovirus vaccine to control poliomyelitis in a developing country--five years after.

The Gaza Strip is an area in transition which in the 1960's had a high prevalence of malnutrition and infectious diseases. The infant mortality was approximatively 140 per 1000 live births. Pediatric Services were almost non-existant. Trivalent oral poliovaccine (TOPV) has been used since 1967. Coverage however did not exceed 70%. From 1973 a network of comprehensive Child Health Centers was spread throughout the area, a set of laws was passed which made vaccination obligatory and the community became heavily involved in health education. These measures resulted in a vaccination coverage, from fixed centers, of over 90% of the susceptible infant population. Though infant mortality decreased rapidly, poliomyelitis was less affected and the mean annual incidence of the paralytic disease until 1977 continued to be 10 per 100,000 inhabitants. Two outbreaks caused by poliovirus Type 1 were registered in 1974 and 1976 with an incidence of 18 per 100,000 inhabitants. In these outbreaks 34% and 50% of the affected children, respectively, had received 3-4 doses of (TOPV). A new vaccination schedule was implemented in 1978 combining TOPV and inactivated polio vaccine in the form of an injectable quadruple vaccine. In the first three years following this change the annual incidence of the paralytic disease dropped from 10 to 2.2 per 100,000 inhabitants. In the following 5 years (1981-1985) only 4 cases of paralytic poliomyelitis were discovered, an annual incidence of 0.16 per 100,000 inhabitants. A serosurvey was done in 1980 on 117 immunized children age 6 months to three years.(ABSTRACT TRUNCATED AT 250 WORDS)