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

Published version
Peer-reviewed

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Authors

Islam, Md. Taufiqul 
Kim, Deok Ryun 
Ahmmed, Faisal 
Chon, Yun 

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.

Description

Keywords

Research Article, Medicine and health sciences, Biology and life sciences

Journal Title

PLOS Neglected Tropical Diseases

Conference Name

Journal ISSN

1935-2735

Volume Title

14

Publisher

Public Library of Science
Sponsorship
Bill and Melinda Gates Foundation (OPP1171432)