Examining the Role of Social Networks and Herd Immunity in a Cholera Vaccine Trial in Bangladesh

Sophia Giebultowicz, University of North Carolina at Chapel Hill
Elisabeth D. Root, University of North Carolina at Chapel Hill
Michael Emch, University of North Carolina at Chapel Hill

A recent study found that in a field trial for a killed oral cholera vaccine in Matlab, Bangladesh, the vaccine conferred herd protection to non-vaccinated individuals based on the levels of coverage in their neighborhood. However, as in traditional vaccine trials, the study assumed equal contact amongst all individuals. This research develops social networks based on demographic data from the vaccine trial population to evaluate whether or not these networks of contacts confer the same protection as levels of neighborhood vaccine coverage. We calculated the number of vaccinated individuals every person in the study area is connected to and found that levels of vaccine coverage in one's social network are positively associated with decreased cholera risk. The results were more significant for vaccinees than for placebo recipients. We plan to also integrate spatial distance into our model to assess the effects of geographic distance between individuals on these protective effects.