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CHILD SURVIVAL UPDATE 54/2009: TWO ON ORAL CHOLERA VACCINES
For many decades, 'cholera vaccine' was a four letter word among public
health people. No more, with the advent of oral formulations. Does any
reader know of countrywide use of oral cholera vaccines? Is it doable?
Good reading.
Bob Davis
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1) ORAL CHOLERA VACCINES FOR CONTROL OF ENDEMIC CHOLERA
In this article from PLOS/Medicine, Longini and colleagues make the case
for the use of oral cholera vaccines to control endemic cholera.
Full text at
http://medicine.plosjournals.org/perlserv/?request=get-document&doi=10.1371%2Fjournal.pmed.0040331
2) MAHALANABIS ON ORAL CHOLERA VACCINE
This article reports a randomized, placebo-controlled trial of the bivalent
killed, whole-cell, oral cholera vaccine in adults and children in a
cholera endemic area in Kolkata, India.
Full text is at
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0002323
Good reading.
Bob Davis
‘Controlling Endemic Cholera with Oral Vaccines’
Ira M. Longini, Jr.1,2*, Azhar Nizam3, Mohammad Ali4, Mohammad Yunus5,
Neeta Shenvi3, John D. Clemens4
1 Vaccine and Infectious Disease Institute, Fred Hutchinson Cancer Research
Center, Seattle, Washington, United States of America, 2 Department of
Biostatistics, School of Public Health and Community Medicine, University
of Washington, Seattle, Washington, United States of America, 3 Department
of Biostatistics, The Rollins School of Public Health, Emory University,
Atlanta, Georgia, United States of America, 4 International Vaccine
Institute, Seoul, Korea, 5 International Centre for Diarrhoeal Disease
Research, Bangladesh, Dhaka, Bangladesh
Background
Although advances in rehydration therapy have made cholera a treatable
disease with low case-fatality in settings with appropriate medical care,
cholera continues to impose considerable mortality in the world's most
impoverished populations. Internationally licensed, killed whole-cell based
oral cholera vaccines (OCVs) have been available for over a decade, but
have not been used for the control of cholera. Recently, these vaccines
were shown to confer significant levels of herd protection, suggesting that
the protective potential of these vaccines has been underestimated and that
these vaccines may be highly effective in cholera control when deployed in
mass immunization programs. We used a large-scale stochastic simulation
model to investigate the possibility of controlling endemic cholera with
OCVs.
Methods and Findings
We construct a large-scale, stochastic cholera transmission model of
Matlab, Bangladesh. We find that cholera transmission could be controlled
in endemic areas with 50% coverage with OCVs. At this level of coverage,
the model predicts that there would be an 89% (95% confidence interval [CI]
72%–98%) reduction in cholera cases among the unvaccinated, and a 93% (95%
CI 82%–99%) reduction overall in the entire population. Even a more modest
coverage of 30% would result in a 76% (95% CI 44%–95%) reduction in cholera
incidence for the population area covered. For populations that have less
natural immunity than the population of Matlab, 70% coverage would probably
be necessary for cholera control, i.e., an annual incidence rate of ≤ 1
case per 1,000 people in the population.
Conclusions
Endemic cholera could be reduced to an annual incidence rate of ≤ 1 case
per 1,000 people in endemic areas with biennial vaccination with OCVs if
coverage could reach 50%–70% depending on the level of prior immunity in
the population. These vaccination efforts could be targeted with careful
use of ecological data.
Citation: Longini IM Jr, Nizam A, Ali M, Yunus M, Shenvi N, et al. (2007)
Controlling Endemic Cholera with Oral Vaccines. PLoS Med 4(11): e336.
doi:10.1371/journal.pmed.0040336
Received: March 5, 2007; Accepted: October 15, 2007; Published: November
27, 2007
Copyright: © 2007 Longini et al. This is an open-access article distributed
under the terms of the Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any medium, provided
the original author and source are credited.
Funding: This work was supported by the National Institute of General
Medical Sciences MIDAS grant U01-GM070749, US National Institute of Allergy
and Infectious Diseases (USAID) grants R01-AI32042 and R01-A139129, and a
grant from the International Vaccine Institute. This work was also
supported by the Diseases of the Most Impoverished Program, funded by the
Bill and Melinda Gates Foundation and coordinated by the International
Vaccine Institute. We also acknowledge the International Centre for
Diarrhoeal Disease Research, Bangladesh (ICDDR,B) for the use of data from
the 1985–1989 Oral Cholera Vaccine Trial conducted with support from USAID
and ICDDR,B unrestricted funds. None of the funding agencies played any
role in study design, data collection and analysis, decision to publish, or
preparation of the manuscript.
Competing interests: The authors have declared that no competing interests
exist.
Abbreviations: CI, confidence interval; ICDDR,B, International Centre for
Diarrhoeal Disease Research, Bangladesh; Research, Bangladesh OCV, oral
cholera vaccine; VE, vaccine efficacy
* To whom correspondence should be addressed. E-mail: longini@scharp.org