The results of benefit-cost analyses may, however, differ from one country to another, and countries should consider local estimates of disease burden, costs treatment, costs of vaccination, and the rates of adverse events for the vaccine strain of interest. Some countries which have attained high measles vaccine coverage and have concerns about the burden of mumps disease may find that they cannot afford to replace monovalent measles vaccine with MMR because of the cost of the vaccine. Benefit-cost analysis may help in approaching potential donors.