Systematic review of immunogenicity and duration of immunity of currently licensed pertussis wP vaccines in children

Abstract

Background: Currently recommended whole cell pertussis (wP) vaccination schedule for children includes a 3-dose primary schedule, and at least one booster dose. When estimating the impact of additional strategies to reduce pertussis burden through modelling, duration of immunity conferred by childhood immunization is among the parameters models are most sensitive to. We aim to assess the duration of immunity of currently available wP vaccines in children and the additional protection conferred by booster doses. Methods: We conducted a systematic review of published studies of current commercially available vaccines indexed in Medline, Embase, Web of Science, Lilacs, SciELO and Central until September 2021. We included clinical trials, observational longitudinal, and cross-sectional studies. Citation screening, data extraction, and risk of bias and methodological quality assessment were done in duplicate by independent reviewers, following the study protocol registered in PROSPERO. Studies were included if they reported primary data on the protection, immunity, or duration of immunity conferred by ≥3 doses of wP vaccine in healthy children, without restriction to time or location of the study. Outcomes included clinical events or serological evidence of protection. Results: We included 12 studies conducted from 2007-2020 with heterogeneous methodological quality. Studies report on 5 of the 18 currently available wP vaccines in use. After primary immunization, geometric mean concentration (GMC) of anti-pertussis toxin ranged from 9.1 EU/mL (95% confidence intervals [CI]: 8.1-10.2) to 50.9 (95%CI: 45.9-56.4). Prior to the 1st booster, GMC titers were low ranging from 4.7 to 10 EU/mL, and after the 1st booster averaged around 42 EU/mL. Conclusions: The limited available evidence on immunogenicity of currently available wP vaccines reinforces the need for booster doses and suggests that the duration of wP immunity is short, probably <5 years. This is important information for vaccination policy makers, investigators and modelers. PROSPERO registration: CRD42018107309