Study shows benefits of mass vaccination post-cholera outbreak

Mass vaccinations for cholera can be beneficial even after an outbreak has begun, according to a new study.

Results of two studies on cholera by the Seoul-based International Vaccine Institute were recently published in PLoS Neglected Tropical Diseases, an online journal published by the Public Library of Science, according to

Experts say the findings could be critical in light of the severe cholera outbreak in Haiti that has left 4,000 dead since October 2010.

“The recent outbreaks of cholera in Haiti, Pakistan and Zimbabwe suggest that current global action plans against cholera are failing,” Edward T. Ryan, a physician from Massachusetts General Hospital said in an article accompanying the study, according to “Less clear is the role that cholera vaccine could play once an outbreak has started."

In one of the two studies, Dang Duc Anh, Anna Lena Lopez and their colleagues from IVI describe a case-control study of an oral vaccine using inactive cholera pathogens that was administered in Hanoi three years previously. The vaccine was later found to be effective 76 percent of the time, reports.

“The findings from this study suggest that reactive use of killed oral cholera vaccines provides protection against the disease and may be a potential tool in times of outbreaks. Further studies must be conducted to confirm these,” the authors of the study wrote, according to

In the other study, IVI researchers Rita Reyburn, Lorenz von Seidlein and John Clemens evaluated the effectiveness of reactive vaccination campaigns.

The researchers used the existing data from cholera outbreaks to simulate a number of preventable cases, assuming that 50 percent to 75 percent of the population would participate in the campaign and that the immunization process would take between 10 to 33 weeks following the first report of an outbreak.

“Even a delayed response can save a substantial number of cases and deaths in long, drawn-out outbreaks,” the study’s authors said, reports.