Cholera Vaccine in Refugee Settings

To the Editor.—The article by Dr Naficy and colleagues¹ regarding the potential for use of oral cholera vaccine in refugee settings may have led to invalid conclusions. At the first node of their decision tree, the authors made assumptions about a population that could benefit from either treatment or vaccine, residing in a camp with medical care provided by Médecins Sans Frontières (MSF). The representative case-fatality data were provided by MSF, a group that has much experience with cholera and from which an unusually low case-fatality rate is expected. The greatest risk factor for fatality in cholera is failure to receive care at a good treatment center; hence, the perspective of the analysis should have been of a displaced person at risk of cholera not just those who reside in an MSF camp. Many cholera epidemics in Africa have had case-fatality rates exceeding 10%,² yet the authors' sensitivity analysis for case-fatality rates only went as high as 3%. If the analysis had compared a "usual-case" scenario for treatment (rather than best case) with the alternative being the use of vaccine, the outcome of the analysis most likely would have been considerably different, even more in favor of vaccine.