Pertussis Epidemic in Lower-Grade Schoolchildren Without Preschool Vaccination Boosters.

We investigated the characteristics of patients with pertussis who did not receive preschool vaccination boosters. Fifteen patients with laboratory-confirmed pertussis and 29 pertussis-negative patients were compared. All pertussis-positive patients, but only 17% of pertussis-negative patients, were elementary school age and older. There is a need to study the utility of routine preschool pertussis vaccine booster in Japan.