What is the primary purpose of vaccines in population health?

• A. To treat infections that already exist.
• B. To prevent infectious diseases and protect vulnerable groups.
• C. To monitor vaccine supply.
• D. To cure common illnesses.

Answer: (B)

Vaccines primarily serve as a preventive measure that reduces disease in a population by building immunity before exposure. By vaccinating a large portion of people, the spread of infection slows or stops, protecting those who are most vulnerable—such as infants, older adults, and individuals with weakened immune systems—who may not be able to be vaccinated or respond well to vaccines. This collective protection, known as herd immunity, lowers overall illness, hospitalizations, and deaths and helps prevent outbreaks.

This is why the other options don’t fit the main goal: vaccines do not treat infections that are already occurring or cure illnesses; they are not intended to monitor vaccine supply, which is a logistical function rather than the purpose of vaccination themselves.