Estimated prevalence of immunity to poliomyelitis in the city of Säo Paulo, Brazil: a population-based survey

RESUMO

OBJECTIVES: Estimate the prevalence of immunity to poliomyelitis (anti-polio antibodies) in the city of Säo Paulo/Brazil through a population-based survey. METHODS: A quantitative and inductive method was used to draw a representative sample of the population. Randomization and stratification (based on sex, age and residence region) was done, and 1,059 individuals were studied on a home-visit basis (structured questionnaires and blood samples). A microneutralization test was performed to detect anti-polio antibodies against serotypes 1, 2 and 3. RESULTS: The estimated prevalence of immunity to poliomyelitis was high, with 94.6 percent prevalence of anti-polio 1 antibodies, 98.8 percent anti-polio 2 and 91.9 percent anti-polio 3. Despite this high prevalence, there were significantly lower prevalence levels in some groups, specially among age and residence region groups. DISCUSSION: Routine child immunization and NIDs with OPV have provided excellent levels of serological immunity to poliomyelitis in the population of the city of Säo Paulo, Brazil. However, there may be specific groups with a lower prevalence of immunity. Estimations of the prevalence of immunity to poliomyelitis were made in a population-based survey, which could be used as an auxiliary tool for supporting the polio eradication program