RESUMO
OBJECTIVES AND METHOD: We conducted a prospective study in 2013 to compare the whole-cell versus acellular pertussis vaccines effectiveness and duration of protection, following the occurrence of pertussis clusters. RESULTS: During seven school outbreaks, we identified 102 clinical pertussis cases, including 10 cases biologically confirmed by Bordetella pertussis specific PCR, among a cohort of 305 children in 2nd to 6th grade. The risk of pertussis when vaccinated with an acellular vaccine alone was 1.6 (RR=1.6; 95% CI=1.1-2.5) times higher than when vaccinated with a whole-cell vaccine or using a combined schedule. CONCLUSIONS: The limited duration of protection conferred by the acellular vaccine reinforces the 2013 introduction of the pertussis booster at six years old.
