Which of the following represents an example of a positive externality in health care?

The optimal choice as an example of a positive externality in health care is the effect of vaccinations reducing disease transmission in the community. Positive externalities occur when an action or decision benefits others who are not directly involved in the action. In this case, when individuals receive vaccinations, they not only protect themselves from the disease but also contribute to herd immunity. This results in fewer outbreaks and reduced transmission of the disease within the community, ultimately benefiting even those who are unvaccinated or not participating in the vaccination program.

The other options do not represent positive externalities in the same way. Hospital readmissions typically signify negative outcomes for patients and indicate inefficiencies in the healthcare system rather than benefits to society. Higher premiums for insurance coverage generally represent increased costs without additional benefits to the public, while long waiting times for appointments reflect systemic issues that detract from the quality of care rather than enhance the health benefits available to the community. Thus, the vaccination scenario stands out as a clear illustration of a positive externality within the realm of health care.