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. 2022 Nov 11;12(11):e066945.
doi: 10.1136/bmjopen-2022-066945.

Effectiveness of two doses of Euvichol-plus oral cholera vaccine in response to the 2017/2018 outbreak: a matched case-control study in Lusaka, Zambia

Cephas Sialubanje  1 , Muzala Kapina  2 , Orbrie Chewe  3   4 , Belem Blamwell Matapo  5   6 , Albertina Moraes Ngomah  7 , Brittany Gianetti  8 , William Ngosa  7 , Mpanga Kasonde  9 , Kunda Musonda  4   10 , Modest Mulenga  11 , C Michelo  12 , Nyambe Sinyange  13 , Patricia Bobo  4 , Khozya Zyambo  14 , Lucy Mazyanga  2 , Nathan Bakyaita  5 , Victor M Mukonka  2   15
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Effectiveness of two doses of Euvichol-plus oral cholera vaccine in response to the 2017/2018 outbreak: a matched case-control study in Lusaka, Zambia

Cephas Sialubanje et al. BMJ Open. .

Abstract

Introduction: Zambia experienced a major cholera outbreak in 2017-2018, with more than 5905 cases reported countrywide, predominantly from the peri-urban slums of Lusaka city. The WHO recommends the use of oral cholera vaccines (OCVs) together with traditional control measures, including health promotion, provision of safe water and improving sanitation, in cholera endemic areas and during cholera outbreaks. In response to this outbreak, the Zambian government implemented the OVC campaign and administered the Euvichol-plus vaccine in the high-risk subdistricts of Lusaka. Although OCVs have been shown to be effective in preventing cholera infection in cholera endemic and outbreak settings, the effectiveness of the Euvichol-plus vaccine has not yet been evaluated in Zambia. This study aimed to determine the effectiveness of two doses of OCV administered during the 2017/2018 vaccination campaign.

Methods: We conducted a matched case-control study involving 79 cases and 316 controls following the mass vaccination campaign in the four subdistricts of Lusaka (Chawama, Chipata, Kanyama and Matero). Matching of controls was based on the place of residence, age and sex. Conditional logistic regression was used for analysis. Adjusted OR (AOR), 95% CI and vaccine effectiveness (1-AOR) for two doses of Euvichol-plus vaccine and any dose were estimated (p<0.05).

Results: The AOR vaccine effectiveness for two doses of Euvichol-plus OCV was 81.0% (95% CI 66.0% to 78.0%; p<0.01). Secondary analysis showed that vaccine effectiveness for any dose was 74.0% (95% CI 50.0% to 86.0%; p<0.01).

Conclusion: These findings show that two doses of Euvichol-plus OCV are effective in a cholera outbreak setting in Lusaka, Zambia. The findings also indicate that two doses are more effective than a single dose and thus support the use of two doses of the vaccine as part of an integrated intervention to cholera control during outbreaks.

Keywords: Epidemiology; Public health; STATISTICS & RESEARCH METHODS.

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Conflict of interest statement

Competing interests: None declared.

Figures

Figure 1
Figure 1
Participant recruitment algorithm. CTC, cholera treatment centre.
See this image and copyright information in PMC

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