Protection conferred by typhoid fever against recurrent typhoid fever in urban Kolkata

PLoS Negl Trop Dis. 2020 Aug 17;14(8):e0008530. doi: 10.1371/journal.pntd.0008530. eCollection 2020 Aug.

Abstract

We evaluated the protection conferred by a first documented visit for clinical care of typhoid fever against recurrent typhoid fever prompting a visit. This study takes advantage of multi-year follow-up of a population with endemic typhoid participating in a cluster-randomized control trial of Vi capsular polysaccharide typhoid vaccine in Kolkata, India. A population of 70,566 individuals, of whom 37,673 were vaccinated with one dose of either Vi vaccine or a control (Hepatitis A) vaccine, were observed for four years. Surveillance detected 315 first typhoid visits, among whom 4 developed subsequent typhoid, 3 due to reinfection, defined using genomic criteria and corresponding to -124% (95% CI: -599, 28) protection by the initial illness. Point estimates of protection conferred by an initial illness were negative or negligible in both vaccinated and non-vaccinated subjects, though confidence intervals around the point estimates were wide. These data provide little support for a protective immunizing effect of clinically treated typhoid illness, though modest levels of protection cannot be excluded.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antibodies, Bacterial
  • Humans
  • India / epidemiology
  • Salmonella typhi / immunology
  • Typhoid Fever / epidemiology*
  • Typhoid Fever / immunology
  • Typhoid Fever / prevention & control*
  • Typhoid-Paratyphoid Vaccines / administration & dosage*
  • Typhoid-Paratyphoid Vaccines / therapeutic use
  • Vaccination

Substances

  • Antibodies, Bacterial
  • Typhoid-Paratyphoid Vaccines