Epidemiology team

Monday, July 18, 2016

IDM Explores Potential Cost-Effective Vaccine Campaign

Cholera is a disease that affects millions in the developing world each year. Untreated, severe dehydration from cholera can kill a person in less than a day. In the 1960's, it was found that inexpensive oral rehydration solution could usually save the lives of those with severe diarrhea. However, when cholera outbreaks strike unprepared and vulnerable populations, as happened in Haiti in 2010, death tolls can be high. The outbreak in Haiti, which continues to this day, renewed interest in using vaccines against cholera.

Bangladesh has a high burden of diarrheal disease, and cholera is responsible for a substantial number of the cases with severe dehydration. Many parts of Bangladesh have predictable seasonal outbreaks. The use of oral cholera vaccine (OCV) offers a possible solution to help reduce and potentially prevent these outbreaks, until there is a sustainable way for these populations to have access to clean water and high-quality sanitation. IDM, in a collaboration with colleagues from other institutions is in the process of preparing a report that will estimate the cost and benefits (reduced cholera cases and deaths) from mass vaccination in Dhaka. Mathematical modeling will be used to estimate how effective mass vaccination can be in reducing the burden of cholera.

Cholera vaccine has only moderately efficacy around 65%. However, if you can vaccinate a large proportion of a vulnerable population, even unvaccinated people benefit from herd protection. If enough people are vaccinated, about 50-70%, cholera transmission could slow to a trickle. Estimating the amount of herd protection, a vulnerable population receives from mass vaccination can be difficult, and mathematical modeling may be required. However, these kinds of calculations are needed to estimate the full benefit of large-scale public health interventions against infectious diseases. IDM’s efforts in Bangladesh and elsewhere will help countries decide how to allocate scarce resources to public health problems.