Coverage for pertussis vaccination during pregnancy with 4 models of vaccine delivery: a quasiexperimental, multicentre observational study

Background: Vaccination of pregnant people with a vaccine containing acellular pertussis (tetanus–diphtheria–acellular pertussis [Tdap]) has been recommended in Canada since 2018, and the evaluation of delivery models for efficient maternal Tdap administration is a priority for the Quebec Ministry of Health. We implemented 3 vaccine delivery models, in addition to the existing standard of practice model, and compared the vaccine coverage achieved by the 4 models in Quebec. Methods: In this quasiexperimental, multicentre observational study, we recruited pregnant people at less than 21 weeks’ gestation in 4 Quebec regions from April to October 2019. We compared 4 vaccine delivery models: local community service centres (centre local de services communautaires [CLSCs], baseline), family medicine groups (FMGs), obstetrics clinic and the oral glucose challenge test (OGCT). In addition to the CLSCs, 3 FMGs, 1 obstetric clinic and a hospital-based OGCT screening program participated. We determined vaccination status from a self-reported questionnaire, the Quebec Immunization Registry or medical charts. We compared model-specific (for participants recruited to a model and subsequently vaccinated within that model) and overall vaccine coverage (considering all vaccine delivery pathways) and used logistic regression to adjust for sociodemographic variables. Results: Overall, 946 of 1000 recruited pregnant people were eligible for analyses. Vaccination via the FMGs achieved the highest model-specific vaccine coverage (67.8%, 95% confidence interval [CI] 60.5%–74.4%), but coverage was not significantly different from the CLSCs (63.8%, 95% CI 57.6%–69.6%). For overall vaccine coverage, the FMG (86.5%, 95% CI 80.6%–90.9%) and obstetrics models (85.9%, 95% CI 80.9%–89.7%) achieved significantly higher vaccine coverage than the CLSCs (66.3%, 95% CI 60.1%–71.9%). The OGCT model did not improve overall vaccine coverage (61.8%, 95% CI 56.1%–67.2%). Interpretation: Compared with CLSCs, overall vaccine coverage was higher when Tdap was offered in FMGs or an obstetrics clinic providing prenatal care. Health professionals involved in pregnancy follow-up recommending and offering the vaccine may be a key factor in optimizing vaccine coverage.