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

      Ferreras, E; Blake, A; Chewe, O; Mwaba, J; Zulu, G; Poncin, M; Rakesh, A; Page, AL; Quilici, ML; Azman, AS; et al. (Cambridge University Press, 2020-03-13)
      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 polymerase chain reaction results. Matched controls by age and sex were selected among neighbours 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 oral cholera vaccine (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 behaviour 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.
    • Alternative observational designs to estimate the effectiveness of one dose of oral cholera vaccine in Lusaka, Zambia

      Ferreras, E; Blake, A; Chewe, O; Mwaba, J; Zulu, G; Poncin, M; Rakesh, A; Page, AL; Quilici, ML; Azman, AS; et al. (Cambridge University Press, 2020-03-13)
      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 polymerase chain reaction results. Matched controls by age and sex were selected among neighbours 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 oral cholera vaccine (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 behaviour 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.
    • Effectiveness of oral cholera vaccine in preventing cholera among fishermen in Lake Chilwa, Malawi: A case-control study

      Grandesso, F; Kasambara, W; Page, AL; Debes, AK; M'bang'ombe, M; Palomares, A; Lechevalier, P; Pezzoli, L; Alley, I; Salumu, L; et al. (Elsevier, 2019-06-19)
      Background: In response to a cholera outbreak among mobile, difficult-to-reach fishermen on Lake Chilwa, Malawi in 2016, a novel vaccine distribution strategy exploited the proven vaccine thermostability. Fishermen, while taking the first vaccine dose under supervision, received the second dose in a sealed bag, and were told to drink it two weeks later. This study assessed short-term vaccine protection of this strategy. Methods: Patients with diarrhoea admitted to health facilities around lake were interviewed and a stool sample collected for PCR testing. Vaccine effectiveness was assessed in a case-control test-negative design by comparing cases (PCR-positive for V. cholerae O1) and controls (patients with diarrhoea but PCR-negative) and with the screening method that compared the proportions of vaccinated among cholera cases versus the general fishermen population. Results: Of 145 study participants, 120 were fishermen living on the lake. Vaccine effectiveness at three-months was 90.0% [95%CI:38.8;98.4] among fishermen and 83.3% [95%CI: 20.8; 96.5] among all participants in the case-control test-negative design, and 97.5% [95%CI: 90.9;99.3] with the screening method. Conclusion: This strategy was effective in providing short-term protection in fishermen against cholera. Further research is needed to determine the adding value of the second dose and to identify the optimal vaccination strategies for different contexts.
    • Highly targeted cholera vaccination campaigns in urban setting are feasible: The experience in Kalemie, Democratic Republic of Congo

      Massing, LA; Aboubakar, S; Blake, A; Page, AL; Cohuet, S; Ngandwe, A; Mukomena Sompwe, E; Ramazani, R; Allheimen, M; Levaillant, P; et al. (Public Library of Science, 2018-05-07)
      Oral cholera vaccines are primarily recommended by the World Health Organization for cholera control in endemic countries. However, the number of cholera vaccines currently produced is very limited and examples of OCV use in endemic countries, and especially in urban settings, are scarce. A vaccination campaign was organized by Médecins Sans Frontières and the Ministry of Health in a highly endemic area in the Democratic Republic of Congo. This study aims to describe the vaccine coverage achieved with this highly targeted vaccination campaign and the acceptability among the vaccinated communities.
    • Oral cholera vaccination in hard-to-reach communities, Lake Chilwa, Malawi

      Grandesso, F; Rafael, F; Chipeta, S; Alley, I; Saussier, C; Nogareda, F; Burns, M; Lechevalier, P; Page, AL; Salumu, L; et al. (The World Health Organization, 2018-12-01)
      To evaluate vaccination coverage, identify reasons for non-vaccination and assess satisfaction with two innovative strategies for distributing second doses in an oral cholera vaccine campaign in 2016 in Lake Chilwa, Malawi, in response to a cholera outbreak.
    • Oral cholera vaccination in hard-to-reach communities, Lake Chilwa, Malawi

      Grandesso, F; Rafael, F; Chipeta, S; Alley, I; Saussier, C; Nogareda, F; Burns, M; Lechevalier, P; Page, AL; Salumu, L; et al. (World Health Organization, 2018-09-27)
    • Single-Dose Cholera Vaccine in Response to an Outbreak in Zambia

      Ferreras, E; Chizema-Kawesha, E; Blake, A; Chewe, O; Mwaba, J; Zulu, G; Poncin, M; Rakesh, A; Page, AL; Stoitsova, S; et al. (Massachusetts Medical Society, 2018-02-08)