Prevention of Typhoid Fever by Existing Improvements in Household Water, Sanitation, and Hygiene, and the Use of the Vi Polysaccharide Typhoid Vaccine in Poor Urban Slums: Results from a Cluster-Randomized Trial

• Published in: The American journal of tropical medicine and hygiene Vol. 106; no. 4; pp. 1149 - 1155
• Main Authors: Im, Justin, Khanam, Farhana, Ahmmed, Faisal, Kim, Deok Ryun, Kang, Sophie, Tadesse, Birkneh Tilahun, Chowdhury, Fahima, Ahmed, Tasnuva, Aziz, Asma Binte, Hoque, Masuma, Islam, Md Taufiqul, Park, Juyeon, Liu, Xinxue, Sur, Dipika, Pak, Gideok, Jeon, Hyon Jin, Zaman, Khalequ, Khan, Ashraful Islam, Qadri, Firdausi, Marks, Florian, Kim, Jerome H, Clemens, John D
• Format: Journal Article
• Language: English
• Published: United States Institute of Tropical Medicine 01.04.2022; The American Society of Tropical Medicine and Hygiene
• Subjects: Dietary Carbohydrates; Households; Humans; Hygiene; Immunization; Medicin och hälsovetenskap; Poverty Areas; Sanitation; Typhoid; Typhoid Fever - epidemiology; Typhoid Fever - prevention & control; Typhoid-Paratyphoid Vaccines; Vaccines; Water
• ISSN: 0002-9637; 1476-1645; 1476-1645
• DOI: 10.4269/ajtmh.21-1034

Modest improvements in household water, sanitation, and hygiene (WASH) and typhoid vaccination can reduce typhoid risk in endemic settings. However, empiric evaluation of their combined impact is lacking. A total of 62,756 persons residing in 80 clusters in a Kolkata slum were allocated randomly 1:1 to either the typhoid Vi polysaccharide (ViPS) vaccine or hepatitis A (Hep A) vaccine. Surveillance was conducted for 2 years before and 2 years after vaccination. We classified households as having "better" or "not better" WASH, and calculated the prevalence of better WASH households in clusters using previously validated criteria. We evaluated the protection by better household WASH, better household WASH prevalence, and ViPS vaccination against typhoid in all cluster members present at baseline using Cox proportional hazard models. Overall, ViPS vaccination was associated with a 55% (P < 0.001; 95% CI, 35-69) reduction of typhoid risk and was similar regardless of better WASH in the residence. Living in a better WASH household was associated with a typhoid risk reduction of 31% (P = 0.16; 95% CI, -16 to 59) overall. The reduction was 48% (P = 0.05; 95% CI, -1 to 73) in Hep A clusters, 6% (P = 0.85; 95% CI, -82 to 51) in ViPS clusters, and 57% (P < 0.05; 95% CI, 15-78) in the population during the 2 years preceding the trial. These findings demonstrate a preventive association of better household WASH in the non-ViPS population, but, unexpectedly, an absence of additional protection from ViPS by better WASH in the ViPS population. This analysis highlights the importance of assessing the combination of WASH in conjunction with typhoid vaccines, and has implications for the evaluation of new-generation typhoid conjugate vaccines.