The Epidemiology of Nationally Reported Pertussis in the United States, 2000-2016

Abstract

Background: Despite successful vaccination programs, pertussis remains endemic in the United States, and increasing incidence has been reported. We used national surveillance data to describe pertussis epidemiology, including patient demographic characteristics, geographic distribution, and temporal trends.

Methods: We included cases reported through the National Notifiable Diseases Surveillance System between 1 January 2000 and 31 December 2016. Differences in case characteristics were compared using Pearson χ2. Average annual incidence (cases per 100 000 population) was calculated overall and by age (<1 year, 1-6 years, 7-10 years, 11-18 years, 19-39 years, 30-64 years, and ≥65 years) and geographic subgroup. Annual percent change was estimated using negative bionomial regression.

Results: During 2000-2016, 339 420 pertussis cases were reported. The majority were in white (88.2%) and non-Hispanic (81.3%) persons, 9.9% were hospitalized, and 0.1% were fatal; however, differences existed by age. Infants had the highest incidence (75.3/100 000 population), accounting for 88.8% of deaths. Incidence increased significantly over time (P = .0019), increases were observed for all groups except persons aged <1 year and 19-64 years. Elevated case counts among persons aged 7-10 and 11-18 years coincided with the aging of acellular-primed cohorts. Incidence varied by geographic region, with some similarities in disease cyclicity.

Conclusions: Increasing baseline incidence and changing age distribution of pertussis suggest a central role of the transition to acellular vaccines in the US disease resurgence. Continued monitoring of national data is important to evaluate and optimize pertussis prevention and control strategies.

Keywords: DTaP; Tdap; immunization; pertussis; waning immunity.