Programmatic Effectiveness of a Pediatric Typhoid Conjugate Vaccine Campaign in Navi Mumbai, India

Abstract

ABSTRACTBackgroundThe WHO recommends vaccines for prevention and control of typhoid fever, especially where antimicrobial-resistant typhoid circulates. In 2018 the Navi Mumbai Municipal Corporation (NMMC), implemented a TCV campaign. The campaign targeted all children aged 9-months through 14-years within NMMC boundaries (∼320,000 children) over 2 vaccination phases. The phase 1 campaign occurred from July 14-August 25, 2018 (71% coverage, ∼113,420 children). We evaluated the campaign’s programmatic effectiveness in reducing typhoid cases at the community level.MethodsWe established prospective, blood culture-based surveillance at 6 hospitals in Navi Mumbai, offering blood cultures to children presenting with fever for at least 3 days. We employed a cluster-randomized test-negative design to estimate the effectiveness of the vaccination campaign on pediatric typhoid cases. We matched culture-confirmed typhoid cases with up to 3 culture-negative controls by age and date of blood culture and assessed community vaccine campaign phase as an exposure using conditional logistic regression.ResultsBetween September 1, 2018–March 31, 2021, we identified 81 typhoid cases and matched these with 238 controls. Cases were 0.44 times as likely to live in vaccine campaign communities (campaign effectiveness, 56%, 95%CI: 25%-74%, p=0.002). Cases ≥ 5-years-old were 0.37 times as likely (95% CI: 0.19-0.70; p-value = 0.002) and cases during the first year of surveillance were 0.30 times as likely (95% CI: 0.14-0.64; p-value = 0.002) to live in vaccine campaign communities.ConclusionsOur findings support the use of TCV mass vaccination campaigns as effective population-based tools to combat typhoid fever.SummaryIn 2018, the Navi Mumbai Municipal Corporation conducted a typhoid conjugate vaccine campaign in half of its communities. Utilizing a test-negative design, we estimate that this campaign reduced typhoid risk by 56% (25-74%) in vaccinated communities compared to non-campaign communities.