Seroprevalence study reveals pertussis underreporting in Brazil and calls for adolescent/young adult boosting: mouse model demonstrates immunity restoration.

BACKGROUND: Pertussis continues to pose a significant threat despite the availability of effective vaccines. The challenge lies in the vulnerability of infants who have not yet completed their vaccination schedule and in adolescents and adults becoming potential disease carriers. METHODS: We evaluated the seroprevalence of pertussis immunity in a cohort of 1,500 healthy Brazilian volunteers. Next, we explored the potential restoration of waning pertussis immunity by administering booster doses of wP, aP or Plow (an economically viable and low reactogenic vaccine in development at Butantan) using a mouse model. FINDINGS: The mean anti-PT IgG levels in the Brazilian volunteers was 39.4 IU/mL. Notably, individuals ≤ 19 years exhibited higher IgG values compared to older age groups (≥ 20 y). Overall, 8.4% of the samples displayed indications of recent or current contact/infection, with IgG levels surpassing 120 IU/mL, particularly in the 15-19 years age group. IgM values were also increased in the 10-19 years age group. Potential recovery of pre-existing but waning immunity investigated in mice, showed that boosting with wP induced higher antibody titers than aP or Plow. Notably, aP and Plow boosts prompted superior effector and memory cell responses from both B and T cells. Upon challenge with B. pertussis, aP or Plow boost provided greater protection as compared to wP. INTERPRETATIONS: Pertussis appears to circulate predominantly among adolescents and young adults. Insights from the mouse model indicate that immunity can be restored with booster doses. Boosting immunity in non-targeted groups could prevent the dissemination of pertussis to infants.