RESUMO
Immunization is an important disease prevention measure, and evaluating the effectiveness of immunization programs is crucial to ensuring their success. This study describes the results of a household survey in four cities in the state of São Paulo, Brazil: Francisco Morato, Guarulhos, Osasco, and São Paulo. The survey was done in order to estimate immunization coverage for the cohort of children born in 1996. The city of São Paulo was divided into five strata, according to socioeconomic and living conditions. The survey followed the methodology that the Pan American Health Organization recommends for immunization coverage surveys. The proportion of children who had received a complete set of the recommended vaccinations at the time of the interview, taking into account both oral reports and information recorded on the children's immunization cards, was above 90% for all the cities except Francisco Morato, which had the worst living conditions. In the city of São Paulo, the worst coverage was found in the lowest and highest strata. When only the doses received during the first year of life were considered, the coverage was not adequate to produce herd immunity. The use of private vaccination services was higher in the areas with better living conditions. The difference between the coverage calculated based on data from health services and the coverage calculated based on the survey was inversely proportional to living conditions. Our results suggest that surveys similar to the one described here should be carried out in other cities. Employees who provide vaccination services should be trained to correctly record vaccination data. In addition, it is important to make health professionals aware of the official immunization calendar, and to facilitate the public's access to health services.