The interplay between WASH practices and vaccination with oral cholera vaccines in protecting against cholera in urban Bangladesh: Reanalysis of a cluster-randomized trial

Fahima Chowdhury; Asma Binte Aziz; Faisal Ahmmed; Tasnuva Ahmed; Sophie Sy Kang; Justin Im; Juyeon Park; Birkneh Tilahun Tadesse; Md Taufiqul Islam; Deok Ryun Kim; Masuma Hoque; Gideok Pak; Farhana Khanam; Nigel A J McMillan; Xinxue Liu; Khalequ Zaman; Ashraful Islam Khan; Jerome H Kim; Florian Marks; Firdausi Qadri; John D Clemens

doi:10.1016/j.vaccine.2023.02.054

The interplay between WASH practices and vaccination with oral cholera vaccines in protecting against cholera in urban Bangladesh: Reanalysis of a cluster-randomized trial

Vaccine. 2023 Mar 31;41(14):2368-2375. doi: 10.1016/j.vaccine.2023.02.054. Epub 2023 Mar 8.

Authors

Fahima Chowdhury¹, Asma Binte Aziz², Faisal Ahmmed³, Tasnuva Ahmed³, Sophie Sy Kang², Justin Im², Juyeon Park⁴, Birkneh Tilahun Tadesse², Md Taufiqul Islam³, Deok Ryun Kim², Masuma Hoque³, Gideok Pak², Farhana Khanam³, Nigel A J McMillan⁵, Xinxue Liu⁶, Khalequ Zaman³, Ashraful Islam Khan³, Jerome H Kim², Florian Marks⁷, Firdausi Qadri³, John D Clemens⁸

Affiliations

¹ International Centre for Diarrheal Disease Research, Bangladesh, Dhaka, Bangladesh; Menzies Health Institute Queensland, Griffith University, Gold Coast, Australia. Electronic address: fchowdhury@icddrb.org.
² International Vaccine Institute, Seoul, Republic of Korea.
³ International Centre for Diarrheal Disease Research, Bangladesh, Dhaka, Bangladesh.
⁴ International Vaccine Institute, Seoul, Republic of Korea; Department of Medicine, University of Cambridge, Cambridge, United Kingdom.
⁵ Menzies Health Institute Queensland, Griffith University, Gold Coast, Australia.
⁶ Oxford Vaccine Group, Department of Pediatrics, University of Oxford, Oxford OX3 9DU, United Kingdom.
⁷ International Vaccine Institute, Seoul, Republic of Korea; Department of Medicine, University of Cambridge, Cambridge, United Kingdom; University of Antananarivo, Antananarivo, Madagascar.
⁸ International Centre for Diarrheal Disease Research, Bangladesh, Dhaka, Bangladesh; International Vaccine Institute, Seoul, Republic of Korea; UCLA Fielding School of Public Health, Los Angeles, CA 90095-1772, USA.

Abstract

The current global initiative to end Cholera by 2030 emphasizes the use of oral cholera vaccine (OCV) combined with feasible household Water-Sanitation-Hygiene (WASH) interventions. However, little is known about how improved WASH practices and behaviors and OCV interact to reduce the risk of cholera. We reanalyzed two arms of a cluster-randomized trial in urban Bangladesh, to evaluate the effectiveness of OCV given as a 2-dose regimen. One arm (30 clusters, n = 94,675) was randomized to vaccination of persons aged one year and older with OCV, and the other arm (30 clusters, n = 80,056) to no intervention. We evaluated the prevention of cholera by household WASH, classified at baseline using a previously validated rule, and OCV over 2 years of follow-up. When analyzed by assignment to OCV clusters rather than receipt of OCV, in comparison to persons living in "Not Better WASH" households in the control clusters, reduction of severe cholera (the primary outcome) was similar for persons in "Not Better WASH" households in vaccine clusters (46%, 95% CI:24,62), for persons in "Better WASH" households in the control clusters (48%, 95% CI:25,64), and for persons in "Better WASH" households in the vaccine clusters (48%, 95% CI:16,67). In contrast, when analyzed by actual receipt of a complete OCV regimen, , in comparison to persons in "Not Better WASH" households in the control clusters, protection against severe cholera increased steadily from 39% (95% CI:13,58) in residents of "Better WASH" households in the control clusters to 57% (95% CI:35,72) in vaccinated persons in "Not Better WASH" households to 63% (95% CI:21,83) in vaccinated persons in "Better WASH" households. This analysis suggests that improved household WASH and OCV received may interact to provide greater protection against cholera. However, the divergence between findings related to intent to vaccinate versus those pertaining to actual receipt of OCV underscores the need for further research on this topic.

Keywords: Cholera; Cluster randomized trials; Oral cholera vaccine; Vaccine effectiveness; WASH.

Publication types

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

MeSH terms

Administration, Oral
Bangladesh
Cholera Vaccines*
Cholera* / epidemiology
Cholera* / prevention & control
Humans
Hygiene
Sanitation
Vaccination
Water

Substances

Cholera Vaccines
Water