Effectiveness of one dose of killed oral cholera vaccine in an endemic community in the Democratic Republic of the Congo: a matched case-control study

A global shortage of cholera vaccines has increased the use of single-dose regimens, rather than the standard two-dose regimen. There is sparse evidence on single-dose protection, particularly in children. In 2020, a mass vaccination campaign was conducted in Uvira, an endemic urban setting in easte...

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Published in:The Lancet infectious diseases 2024-05, Vol.24 (5), p.514-522
Main Authors: Malembaka, Espoir Bwenge, Bugeme, Patrick Musole, Hutchins, Chloe, Xu, Hanmeng, Hulse, Juan Dent, Demby, Maya N, Gallandat, Karin, Saidi, Jaime Mufitini, Rumedeka, Baron Bashige, Itongwa, Moïse, Tshiwedi-Tsilabia, Esperance, Kitoga, Faida, Bodisa-Matamu, Tavia, Kavunga-Membo, Hugo, Bengehya, Justin, Kulondwa, Jean-Claude, Debes, Amanda K, Taty, Nagède, Lee, Elizabeth C, Lunguya, Octavie, Lessler, Justin, Leung, Daniel T, Cumming, Oliver, Okitayemba, Placide Welo, Mukadi-Bamuleka, Daniel, Knee, Jackie, Azman, Andrew S
Format: Article
Language:English
Subjects:
Administration, Oral
Adolescent
Adult
Case studies
Case-Control Studies
Child
Child, Preschool
Children
Cholera
Cholera - epidemiology
Cholera - prevention & control
Cholera Vaccines - administration & dosage
Cholera Vaccines - immunology
Democratic Republic of the Congo - epidemiology
Demographic variables
Demographics
Drinking water
Effectiveness
Endemic Diseases - prevention & control
Epidemics
Estimates
Female
Health facilities
Households
Humans
Immunization
Infant
Male
Mass Vaccination
Middle Aged
Observational studies
Regression analysis
Regression models
Urban areas
Urban environments
Vaccination
Vaccination - statistics & numerical data
Vaccine Efficacy
Vaccines
Vaccines, Inactivated - administration & dosage
Vaccines, Inactivated - immunology
Waterborne diseases
Young Adult
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Summary:A global shortage of cholera vaccines has increased the use of single-dose regimens, rather than the standard two-dose regimen. There is sparse evidence on single-dose protection, particularly in children. In 2020, a mass vaccination campaign was conducted in Uvira, an endemic urban setting in eastern Democratic Republic of the Congo, resulting in largely single-dose coverage. We examined the effectiveness of a single-dose of the oral cholera vaccine Euvichol-Plus in this high-burden setting. In this matched case-control study, we recruited individuals with medically attended confirmed cholera in the two cholera treatment facilities in the city of Uvira. The control group consisted of age-matched, sex-matched, and neighbourhood-matched community individuals. We recruited across two distinct periods: Oct 14, 2021, to March 10, 2022 (12–17 months after vaccination), and Nov 21, 2022, to Oct 18, 2023 (24–36 months after vaccination). Study staff administered structured questionnaires to all participants to capture demographics, household conditions, potential confounding variables, and vaccination status. The odds of vaccination for the case and control groups were contrasted in conditional logistic regression models to estimate unadjusted and adjusted vaccine effectiveness. We enrolled 658 individuals with confirmed cholera and 2274 matched individuals for the control group. 99 (15·1%) individuals in the case group were younger than 5 years at the time of vaccination. The adjusted single-dose vaccine effectiveness was 52·7% (95% CI 31·4 to 67·4) 12–17 months after vaccination and 44·7% (24·8 to 59·4) 24–36 months after vaccination. Although protection in the first 12–17 months after vaccination was similar for children aged 1–4 years and older individuals, the estimate of protection in children aged 1–4 years appeared to wane during the third year after vaccination (adjusted vaccine effectiveness 32·9%, 95% CI –30·7 to 65·5), with CIs spanning the null. A single dose of Euvichol-Plus provided substantial protection against medically attended cholera for at least 36 months after vaccination in this cholera-endemic setting. Although the evidence provides support for similar levels of protection in young children and others in the short term, protection among children younger than 5 years might wane significantly during the third year after vaccination. Wellcome Trust and Gavi, the Vaccine Alliance.
ISSN:1473-3099
1474-4457
DOI:10.1016/S1473-3099(23)00742-9