Vaccination strategies for epidemic cholera in Haiti with implications for the developing world
Dennis L. Chao
a, M. Elizabeth Hallorana,b, and Ira M. Longini, Jr.
a Center for Statistics and Quantitative Infectious Diseases, Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle,
WA 98109; and
b Department of Biostatistics, School of Public Health, University of Washington, Seattle, WA 98195
Edited by G. Balakrish Nair, National Institute of Cholera and Enteric Diseases, Kolkata, India, and approved March 16, 2011 (received for review February 9, 2011)
Full text is at http://www.pnas.org/content/early/2011/04/05/1102149108.full.pdf
In October 2010, a virulent South Asian strain of El Tor cholera began to spread in Haiti. Interventions have included treatment of cases and improved sanitation. Use of cholera vaccines would likely have further reduced morbidity and mortality, but such vaccines are in short supply and little is known about effective vaccination strategies for epidemic cholera. We use a mathematical cholera transmission model to assess different vaccination strategies. With limited vaccine quantities, concentrating vaccine in high-risk areas is always most efficient. We show that targeting one million doses of vaccine to areas with high exposure to Vibrio cholerae, enough for two doses for 5% of the population, would reduce the number of cases by 11%. The same strategy with enough vaccine for 30% of the population with modest hygienic improvement could reduce cases by 55% and save 3,320 lives. For epidemic cholera, we recommend a large mobile stockpile of enough vaccine to cover 30% of a country s population to be reactively targeted to populations at high risk of exposure.