Abstract

A POORLY controlled vaccine-preventable disease in the United States, despite a well-established childhood vaccination program and high coverage. 1Although infants have substantially higher rates of pertussis compared with other age groups, data from the National Notifiable Diseases Surveillance System reflect a recent increase in the number of reported pertussis cases among children aged 7 to 10 years.In 2010, this age group had the second highest incidence of pertussis in the United States. 2 The changing epidemiology raises important questions about possible waning protection from the childhood acellular pertussis vaccine series.After the diphtheria, tetanus, and whole-cell pertussis (DTwP) vaccine was introduced in the late 1940s, a dramatic decline occurred in the number of reported pertussis cases.However, whole-cell vaccine was commonly associated with local adverse events (eg, redness, swelling, and pain at the injection site) and less commonly with more serious adverse events. 3,4These safety concerns prompted development and licensure of diphtheria, tetanus, and acellular pertussis (DTaP) vaccines, which were recommended by the