Which statement describes a pro of live attenuated vaccines?

• A. Immune reaction similar to natural infection and lifetime immunity with one dose
• B. They require multiple boosters and are less durable
• C. They cannot cause any adverse reactions
• D. They require no special storage

Answer: (A)

Live, weakened vaccines provoke an immune response that closely resembles what happens during a natural infection. Because the organism can replicate in the body, the immune system is exposed to the pathogen’s antigens in a way that trains it effectively, often creating strong, lasting protection after just one dose. This is why they’re considered a pro: they can produce immunity similar to natural exposure and, for many vaccines, durable protection with minimal dosing.

The idea that boosters are always required, that adverse reactions can be avoided entirely, or that no special storage is needed does not fit this approach. Live attenuated vaccines can sometimes require boosters, can cause mild reactions in some people, and usually need careful temperature-controlled storage to remain effective.