A Population-Based Study of Recurrent Symptomatic Bordetella pertussis Infections in Children in California, 2010-2015

Background. Natural infection with Bordetella pertussis is thought to result in 4-20 years of immunity against subsequent symptomatic pertussis infection. However, these estimates are based on studies in unvaccinated or whole-cell pertussis-vaccinated children. We conducted a population-based study of pertussis infection and reinfection during a 5-year period in California in an cohort vaccinated exclusively with acellular pertussis (aP) vaccine. Methods. California surveillance data were reviewed to identify all children with 2 reported incidents of pertussis with symptom onset between 1 January 2010 and 31 December 2015. Case investigation reports were reviewed, and children with ≥2 episodes of symptomatic pertussis infection that met the case definition were included. Results. Of 26 259 pertussis cases reported in children (aged <18 years), 27 children met the inclusion criteria. Recurrent cases occurred among children of all ages; 5 (19%) were <6 months of age at the time of their first illness. The time from initial infection to reinfection was <1 year in 11 (41%) cases. Twenty-one children (78%) had received ≥3 doses of diphtheria and tetanus toxoids and aP vaccine at the time of their first pertussis infection, 1 (4%) had received 1 dose, and 5 (19%) were unvaccinated. Conclusions. Recurrent cases of pertussis infection are extremely rare. Based on this surveillance data, approximately 0.1% of children who were infected with pertussis experienced a clinically significant second episode of pertussis within 4 years. More research is needed to understand the immune response to B. pertussis infection in children vaccinated with aP vaccines.