Administering cholera vaccines to people in Haiti who live in high-risk areas could drive down the number of cholera infections and deaths in the country, according to a study published online Monday in the Proceedings of the National Academy of Sciences, Nature News reports. The study is the latest to weigh in on the impact such vaccination efforts could have on reducing the spread of the disease, which has sickened 274,418 people and led to the deaths of 4,787 in Haiti, according to the publication (Brower, 4/11).

“Using computer models that replicated the spread of the epidemic that began [in Haiti] last October,” researchers from Fred Hutchinson Cancer Center in Seattle, Washington, “simulated various proactive and reactive vaccination strategies,” according to a Fred Hutchison Cancer Research Center press release (4/11). 

According to the model, the researchers found “combined with basic public-health measures, vaccinating the 5% of Haitians most at risk of the disease would reduce the number of cholera cases by 11%. Vaccinating 30% of the population could cut cases by 55%, preventing 3,320 deaths,” the publication writes.

“What we are saying is embarrassingly simple,” lead author Dennis Chao, an epidemiologist at Fred Hutchison Cancer Center, said, adding, “If there is a limited amount of vaccine, obviously we should vaccinate people in areas with big numbers of the disease.” However, “even vaccinating 5% of Haitians would require more doses – a million – than are currently available,” Nature News writes.

Researchers estimate there are roughly between 400,000 and 600,000 doses of oral cholera vaccines, study co-author Ira Longini, an epidemiologist at the University of Washington in Seattle, explained, adding that each vaccination requires two doses. The article describes how the global shortage of cholera vaccines has influenced the country’s response to the outbreak and the two available vaccines that currently exist – Dukoral, which has received approval by the WHO, and the lower-cost Shanchol, which is licensed in India, but “is still undergoing the WHO’s approval process.”

“We believe there should be a comprehensive global plan for the use of cholera vaccine for epidemic cholera,” including the creation of “a large international mobile stockpile of oral cholera vaccine,” the authors write in the study. “This stockpile should be large enough to vaccinate reactively 50-70% of the population at risk for high exposure in the affected country. … Because both vaccines can be made relatively cheaply, current cost of about $5 U.S. for Dukoral and $1.50 U.S. for Shanchol, an international investment case could be made to support production and distribution of these vaccines,” they write (Chao et al., 4/11).

According to Nature News, “[t]he International Vaccine Institute in Seoul is preparing a report for the WHO that will detail how many cholera vaccines should be stockpiled” (4/11).