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

• Main Authors: Justin Im (Author), Md Taufiqul Islam (Author), Deok Ryun Kim (Author), Faisal Ahmmed (Author), Yun Chon (Author), K Zaman (Author), Ashraful Islam Khan (Author), Mohammad Ali (Author), Dipika Sur (Author), Suman Kanungo (Author), Shanta Dutta (Author), Sujit K Bhattacharya (Author), Gordon Dougan (Author), Kathryn E Holt (Author), Florian Marks (Author), Jerome H Kim (Author), Firdausi Qadri (Author), John D Clemens (Author)
• Format: Book
• Published: Public Library of Science (PLoS), 2020-08-01T00:00:00Z.
• Subjects: article
• Online Access: Connect to this object online.

Summary

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.

Item Description

1935-2727
1935-2735
10.1371/journal.pntd.0008530