Which statement best describes the MMR vaccine?

• A. It is an inactivated vaccine
• B. It is a live attenuated vaccine protecting against measles, mumps, and rubella
• C. It contains only the measles component
• D. It is contraindicated in pregnancy due to live virus

Answer: (B)

The main concept is that MMR is a live attenuated combination vaccine against three viruses. It uses weakened forms of measles, mumps, and rubella so the viruses can replicate just enough to train the immune system without causing disease in healthy individuals. This is why it’s described as a live attenuated vaccine that protects against all three diseases with a single formulation. It isn’t inactivated, and it isn’t limited to just measles. The note about pregnancy being a contraindication reflects safety considerations for live vaccines, since they can pose risks to the fetus, but the essential description of the vaccine is that it combines three live, attenuated viruses.