Vaccination against cholera in Juba
TLDR
It is shown that WaSH activities must remain the cornerstone of cholera control and elimination strategies, even if they are difficult to implement, and that Reactive vaccination campaigns might help, provided they are promptly rolled out and include two doses as originally recommended.Abstract:
In an interesting Personal View, Lucy Parker and colleagues1 reported the difficulties regarding implementation of a reactive oral cholera vaccination (OCV) campaign during the 2015 cholera epidemic in Juba, South Sudan.1 They support the choice to address the global shortage of vaccines by providing just one dose to twice the number of people. However, the epidemic curve provided by Parker and colleagues suggests that the South Sudan epidemic was not hugely affected by this campaign. Indeed, the basic reproductive number (R0), which we calculated as previously described2 using data extracted from this curve with the Plot Digitizer tool and R software, using the R0 package, was not reduced after the campaign was finally launched on July 31, 2015; the R0 was already less than 1 between the first peak on June 28 and the start of the OCV campaign (0·94 [95% CI 0·92–0·95]), only 0·72 (0·66–0·78) between the second peak on July 19 and the start of OCV, and still 0·92 (0·90–0·94) from the start of OCV until the last confirmed case on Sept 12, 2015.
Several complementary factors might explain such a disappointing effect. First, vaccine effectiveness of this one-dose campaign could have been lower than the 87·3% (95% CI 70·2 – 100) calculated in a case-cohort observational study by the same group of authors.3 Efficacy of one-dose OCV was estimated to be about 40% (95% CI 11–60) in a double-blind placebo-controlled clinical trial.4 Using the WHO screening method5 with provided data, we calculated that 36% of cholera cases were expected to occur in vaccinated individuals in Juba. The observed proportion was only 6%,3 which suggests biases that the authors could not address despite their efforts to do so. Second, one-dose OCV did not generate any obvious herd immunity, even in the area targeted by mass vaccination, where coverage reached 64%;3 surprisingly, vaccine effectiveness tended to be much higher there (97%) than in the non-mass-vaccinated area (66% with 19% coverage),3 and the calculated cholera attack rate among non-vaccinees was two times higher than in the non-mass-vaccinated area (2·5 vs 1·3 cases per 10 000 inhabitants). 3 Finally, this late campaign probably provided little additional protection to a population in which adaptations to water sanitation and hygiene (WaSH) behaviour—rather than acquired immunity—were probably already reducing cholera transmission.
This insightful cholera vaccination field report shows that WaSH activities must remain the cornerstone of cholera control and elimination strategies, even if they are difficult to implement. Reactive vaccination campaigns might help, provided they are promptly rolled out and include two doses as originally recommended.read more
Citations
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Journal ArticleDOI
The cholera outbreak in Yemen: lessons learned and way forward
Frederik Federspiel,Mohammad Ali +1 more
TL;DR: The Yemen cholera outbreak highlights the importance for international humanitarian health organizations to have a continuous discussion about whether and to what extent they should increase their focus on pre-emptively addressing the environmental determinants of communicable diseases in humanitarian emergencies.
Journal ArticleDOI
Prolonging herd immunity to cholera via vaccination: Accounting for human mobility and waning vaccine effects.
TL;DR: It is shown that vaccination may be best targeted at populations with intermediate degrees of mobility as compared to communities with very high or very low population turnover, and a community could be protected longer by a blended “Mass and Maintain” strategy.
References
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Host and Pathogen Factors for Clostridium difficile Infection and Colonization
Vivian G. Loo,Anne-Marie Bourgault,Louise Poirier,François Lamothe,Sophie Michaud,Nathalie Turgeon,Baldwin Toye,Axelle Beaudoin,Eric Frost,Rodica Gilca,Paul Brassard,Nandini Dendukuri,Claire Béliveau,Matthew Oughton,Ivan Brukner,Andre Dascal +15 more
TL;DR: Health care-associated C. difficile infection and colonization were differentially associated with defined host and pathogen variables, whereas asymptomatic patients were more likely to be colonized with other strains.
Journal Article
Field evaluation of vaccine efficacy.
Walter A. Orenstein,Roger H. Bernier,Dondero Tj,Alan R. Hinman,Marks Js,Kenneth J. Bart,Sirotkin B +6 more
TL;DR: The epidemiological techniques available for measuring vaccine efficacy are described and a practical approach to their use is recommended, including screening, outbreak investigations, secondary attack rates in families or clusters, vaccine coverage assessment, and case-control studies.
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Impact of a Reduction in the Use of High-Risk Antibiotics on the Course of an Epidemic of Clostridium difficile-Associated Disease Caused by the Hypervirulent NAP1/027 Strain
TL;DR: It is suggested that nonrestrictive measures to optimize antibiotic usage can yield exceptional results when physicians are motivated and that such measures should be a mandatory component of n-CDAD control.
Journal ArticleDOI
Efficacy of a Single-Dose, Inactivated Oral Cholera Vaccine in Bangladesh.
Firdausi Qadri,Thomas F. Wierzba,Mohammad Ali,Fahima Chowdhury,Ashraful Islam Khan,Amit Saha,Iqbal Ahmed Khan,Muhammad Asaduzzaman,Afroza Akter,Arifuzzaman Khan,Yasmin Ara Begum,Taufiqur Rahman Bhuiyan,Farhana Khanam,Mohiul I. Chowdhury,Taufiqul Islam,Atique Iqbal Chowdhury,Anisur Rahman,Shah Alam Siddique,Young Ae You,Deok Ryun Kim,Ashraf Siddik,Nirod Chandra Saha,Alamgir Kabir,Alejandro Cravioto,Sachin N. Desai,Ajit Pal Singh,John D. Clemens,John D. Clemens +27 more
TL;DR: A single dose of the oral cholera vaccine was efficacious in older children (≥5 years of age) and in adults in a setting with a high level of cholERA endemicity, although the differences according to age were not significant.
Journal ArticleDOI
Effectiveness of one dose of oral cholera vaccine in response to an outbreak: a case-cohort study.
Andrew S. Azman,Andrew S. Azman,Lucy Anne Parker,Lucy Anne Parker,John Rumunu,Fisseha Tadesse,Francesco Grandesso,Lul Deng,Richard Laku Lino,Bior K. Bior,Michael Lasuba,Anne Laure Page,Lameck Ontweka,Augusto E. Llosa,Sandra Cohuet,Lorenzo Pezzoli,Dossou Vincent Sodjinou,Abdinasir Abubakar,Amanda K. Debes,Allan M. Mpairwe,Joseph F. Wamala,Christine Jamet,Justin Lessler,David A. Sack,Marie Laure Quilici,Iza Ciglenecki,Francisco J. Luquero +26 more
TL;DR: One dose of Shanchol was effective in preventing medically attended cholera in this study and support the use of a single-dose strategy in outbreaks in similar epidemiological settings.