The Centers for Disease Control and Prevention (CDC) wants at least 90 percent of the population vaccinated against preventable diseases, since the chance of a disease outbreak decreases as vaccine coverage increases. We can conclude that:
A) the external benefits of vaccination likely decrease as more and more people are vaccinated.
B) the private benefits of vaccination increase with vaccine coverage.
C) vaccines create a negative externality once the vaccine covers 90 percent of the population.
D) vaccines create a positive externality once the vaccine covers 90 percent of the population.

Question

Quizplus · Accepted Answer

As more people are vaccinated, the external benefits decrease because the risk of disease spread is reduced, meaning each additional vaccination contributes less to overall herd immunity.

The Centers for Disease Control and Prevention (CDC) Wants at Least