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

• Published in: PLoS neglected tropical diseases Vol. 14; no. 8; p. e0008530
• Main Authors: Im, Justin, Islam, Md. Taufiqul, Kim, Deok Ryun, Ahmmed, Faisal, Chon, Yun, Zaman, K., Khan, Ashraful Islam, Ali, Mohammad, Sur, Dipika, Kanungo, Suman, Dutta, Shanta, Bhattacharya, Sujit K., Dougan, Gordon, Holt, Kathryn E., Marks, Florian, Kim, Jerome H., Qadri, Firdausi, Clemens, John D.
• Format: Journal Article
• Language: English
• Published: San Francisco Public Library of Science 01.08.2020; Public Library of Science (PLoS)
• Subjects: Age; Antibiotics; Bacterial infections; Biology and Life Sciences; Capsular polysaccharides; Cholera; Confidence intervals; Disease; Disease control; Fever; Genomes; Genomics; Health aspects; Health surveillance; Hepatitis; Hepatitis A; Illnesses; Immunity (Physiology); Immunization; Infections; Medical research; Medicine and Health Sciences; Physiological aspects; Polysaccharides; Prevention; Protection; Public health; Recurrence (Disease); Supervision; Tropical diseases; Typhoid; Typhoid fever; Typhoid vaccines; Vaccination; Vaccines; Waterborne diseases; India; Los Angeles California; Bangladesh; South Korea; West Bengal India; United Kingdom > UK; United States > US; California; Kolkata India
• ISSN: 1935-2735; 1935-2727; 1935-2735
• DOI: 10.1371/journal.pntd.0008530

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.