<p>Governments face the choice of whether to make vaccinations mandatory. Individuals may not know the quality of the vaccine nor the preferences of the government. In a stylized model, it is shown that if sanctions for non-compliance are sufficiently high, then individuals will be less likely to believe that the government is taking the vaccine’s quality into consideration. Low prior belief that it does so discourages vaccination. If a government is competent in evaluating vaccines and individuals believe that it is taking vaccine quality into account, then an equilibrium exists in which vaccination is voluntary.</p>