Outcomes of Bordetella pertussis infection were studied in 3 age groups (1–3, 4–6, and 7–15 years) during outbreaks in one day care center (n = 29) and in two elementary schools (n = 210). A total of 76 children were confirmed as having B. pertussis infection; 74 were confirmed by polymerase chain reaction (PCR) and 18 by culture. A positive PCR result was less common in children 1–3 years old than in those 4–6 (P= .006). Asymptomatic B. pertussis infection was more common in preschool children than in schoolchildren (P< .001), whereas schoolchildren presented with symptoms compatible with clinical pertussis more often than preschool children (60/210 vs, 3/29, P = .029). In the community of 12,691, the attack rate (laboratory-confirmed patients/l00,000) was 317 in children 15 years. The protection provided by conventional pertussis vaccine is evidently rather short-lived, and booster vaccinations are needed to eradicate pertussis among schoolchildren and adults.