Alternative observational designs to estimate the effectiveness of one dose of oral cholera vaccine in Lusaka, Zambia

E. Ferreras, A. Blake, O. Chewe, J. Mwaba, G. Zulu, M. Poncin, A. Rakesh, A. L. Page, M. L. Quilici, A. S. Azman, S. Cohuet, I. Ciglenecki, K. Malama, E. Chizema-Kawesha, F. J. Luquero

Research output: Contribution to journalArticlepeer-review

Abstract

We conducted a matched case-control (MCC), test-negative case-control (TNCC), and case-cohort study in 2016 in Lusaka, Zambia, following a mass vaccination campaign. Confirmed cholera cases served as cases in all three study designs. In the TNCC, control-subjects were cases with negative cholera culture and PCR results. Matched controls by age and sex were selected among neighbors of the confirmed cases in the MCC study. For the case-cohort study, we recruited a cohort of randomly selected individuals living in areas considered at risk of cholera. We recruited 211 suspected cases (66 confirmed cholera cases and 145 non-cholera diarrhoea cases), 1055 matched controls and a cohort of 921. Adjusted vaccine effectiveness of one dose of OCV was 88.9% (95% confidence interval (CI): 42.7-97.8%) in the MCC study, 80.2% (95% CI: 16.9-95.3%) in the TNCC design and 89.4% (95% CI: 64.6-96.9%) in the case-cohort study. Three study designs confirmed the short-term effectiveness of single dose OCV. Major healthcare-seeking behavior bias did not appear to affect our estimates. Most of the protection among vaccinated individuals could be attributed to the direct effect of the vaccine.

Original languageEnglish (US)
JournalEpidemiology and infection
DOIs
StateAccepted/In press - 2020

ASJC Scopus subject areas

  • Epidemiology
  • Infectious Diseases

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