Vaccine conditions reduce disease by 99% by motivating behavior.

Consider, for example, the case of compulsory vaccination. Compulsory immunization relies on the threat of sanctions to motivate a desired behavior. For instance, states might withhold school entrance or restrict place of residence for those who fail to comply. This kind of policy has met with great success in eradicating several diseases. Some comparative studies show that compulsory immunization programs have reduced vaccine-preventable diseases by 98-99% in many developed countries (Salmon et al., 2006). Other things being equal, the possibility of administering vaccines on a voluntary basis can increase the risk of multiple diseases that could be controlled under a compulsory scheme. Even though there are anti-vaccination movements, it seems difficult to make the case that all vaccines should be administrated on a voluntary basis, since the costs in terms of individual freedom are relatively low and the benefits each individual receives by living in a healthy society relatively high.