 Although collective action in the form of government intervention is thus not a necessary condition of public health, government intervention is still central to public health. Achieving good public health outcomes frequently requires extensive coordination on the part of many actors. To secure coordination, incentive structures for individuals often need to be changed, and it is most often governments that have the authority to make these changes. Because of this authority, governments are especially well-suited to overcome characteristic challenges in promoting or realizing public health. Consider, for example, a paradigmatic challenge in deploying vaccines to combat infectious disease. If enough people are not willing to be vaccinated, then herd immunity is undermined. A central though contested function of government is to disincentivize going unvaccinated by implementing policies that penalize those who refuse vaccination.