There is an emerging body of evidence on the need for and timing of a booster dose for the currently available COVID-19 vaccines. What is the benefit of taking booster dose(s)?

• A. It is important to elicit a primary immune response against a pathogen in the body.
• B. The constituents of the booster dose kill the pathogen when it enters the body.
• C. It restores body's immunity against a pathogen to protective levels as memory for that pathogen deteriorates over time.
• D. All of the above.

Answer: (C)