Andrew S Azman1, Lucy A Parker2, John Rumunu3, Fisseha Tadesse4, Francesco Grandesso4, Lul L Deng3, Richard Laku Lino3, Bior K Bior3, Michael Lasuba3, Anne-Laure Page4, Lameck Ontweka5, Augusto E Llosa4, Sandra Cohuet4, Lorenzo Pezzoli6, Dossou Vincent Sodjinou7, Abdinasir Abubakar8, Amanda K Debes9, Allan M Mpairwe10, Joseph F Wamala10, Christine Jamet11, Justin Lessler12, David A Sack9, Marie-Laure Quilici13, Iza Ciglenecki11, Francisco J Luquero14. 1. Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA; Médecins Sans Frontières, Geneva, Switzerland. Electronic address: azman@jhu.edu. 2. Médecins Sans Frontières, Geneva, Switzerland; CIBER Epidemiología y Salud Pública, Universidad Miguel Hernández, Alicante, Spain. 3. Republic of South Sudan Ministry of Health, Juba, South Sudan. 4. Epicentre, Paris, France. 5. AMREF Health Africa, Juba, South Sudan. 6. World Health Organization, Geneva, Switzerland. 7. World Health Organization, Brazzaville, Republic of the Congo. 8. World Health Organization, Cairo, Egypt. 9. Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA. 10. World Health Organization, Juba, South Sudan. 11. Médecins Sans Frontières, Geneva, Switzerland. 12. Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA. 13. Bacterial Pathogens Unit, Institut Pasteur, Paris, France. 14. Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA; Epicentre, Paris, France.
Abstract
BACKGROUND: Oral cholera vaccines represent a new effective tool to fight cholera and are licensed as two-dose regimens with 2-4 weeks between doses. Evidence from previous studies suggests that a single dose of oral cholera vaccine might provide substantial direct protection against cholera. During a cholera outbreak in May, 2015, in Juba, South Sudan, the Ministry of Health, Médecins Sans Frontières, and partners engaged in the first field deployment of a single dose of oral cholera vaccine to enhance the outbreak response. We did a vaccine effectiveness study in conjunction with this large public health intervention. METHODS: We did a case-cohort study, combining information on the vaccination status and disease outcomes from a random cohort recruited from throughout the city of Juba with that from all the cases detected. Eligible cases were those aged 1 year or older on the first day of the vaccination campaign who sought care for diarrhoea at all three cholera treatment centres and seven rehydration posts throughout Juba. Confirmed cases were suspected cases who tested positive to PCR for Vibrio cholerae O1. We estimated the short-term protection (direct and indirect) conferred by one dose of cholera vaccine (Shanchol, Shantha Biotechnics, Hyderabad, India). FINDINGS: Between Aug 9, 2015, and Sept 29, 2015, we enrolled 87 individuals with suspected cholera, and an 898-person cohort from throughout Juba. Of the 87 individuals with suspected cholera, 34 were classified as cholera positive, 52 as cholera negative, and one had indeterminate results. Of the 858 cohort members who completed a follow-up visit, none developed clinical cholera during follow-up. The unadjusted single-dose vaccine effectiveness was 80·2% (95% CI 61·5-100·0) and after adjusting for potential confounders was 87·3% (70·2-100·0). INTERPRETATION: One dose of Shanchol was effective in preventing medically attended cholera in this study. These results support the use of a single-dose strategy in outbreaks in similar epidemiological settings. FUNDING: Médecins Sans Frontières.
BACKGROUND: Oral cholera vaccines represent a new effective tool to fight cholera and are licensed as two-dose regimens with 2-4 weeks between doses. Evidence from previous studies suggests that a single dose of oral cholera vaccine might provide substantial direct protection against cholera. During a cholera outbreak in May, 2015, in Juba, South Sudan, the Ministry of Health, Médecins Sans Frontières, and partners engaged in the first field deployment of a single dose of oral cholera vaccine to enhance the outbreak response. We did a vaccine effectiveness study in conjunction with this large public health intervention. METHODS: We did a case-cohort study, combining information on the vaccination status and disease outcomes from a random cohort recruited from throughout the city of Juba with that from all the cases detected. Eligible cases were those aged 1 year or older on the first day of the vaccination campaign who sought care for diarrhoea at all three cholera treatment centres and seven rehydration posts throughout Juba. Confirmed cases were suspected cases who tested positive to PCR for Vibrio cholerae O1. We estimated the short-term protection (direct and indirect) conferred by one dose of cholera vaccine (Shanchol, Shantha Biotechnics, Hyderabad, India). FINDINGS: Between Aug 9, 2015, and Sept 29, 2015, we enrolled 87 individuals with suspected cholera, and an 898-person cohort from throughout Juba. Of the 87 individuals with suspected cholera, 34 were classified as cholera positive, 52 as cholera negative, and one had indeterminate results. Of the 858 cohort members who completed a follow-up visit, none developed clinical cholera during follow-up. The unadjusted single-dose vaccine effectiveness was 80·2% (95% CI 61·5-100·0) and after adjusting for potential confounders was 87·3% (70·2-100·0). INTERPRETATION: One dose of Shanchol was effective in preventing medically attended cholera in this study. These results support the use of a single-dose strategy in outbreaks in similar epidemiological settings. FUNDING: Médecins Sans Frontières.
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