The costs and benefits of vaccinating troops on United Nations tours in Yugoslavia against hepatitis A were compared. The marginal cost of one case of hepatitis A avoided by vaccination was calculated and compared with the marginal cost of achieving the same outcome by passive immunization. The cost-benefit ratio (medium estimate) for troops at low risk of contracting hepatitis A was 0.01 and for those at high risk was 0.03.
Vaccinating troops against hepatitis A for a single deployment appears to be an inefficient procedure, especially in troops at low risk. However, in professional troops from countries of low hepatitis A endemicity who are likely to be involved in several operational deployments, vaccination becomes more efficient the more times the same troops are deployed.