The MMR vaccine should be given at what age?

• A. 6 months
• B. 1 year
• C. 18 months
• D. 2 years

Answer: (B)

The timing of the first MMR dose is chosen to balance two things: the child’s ability to mount a strong immune response and the need to protect early in life. After birth, maternal antibodies against measles, mumps, and rubella decline over the first year. If the vaccine is given too early—around 6 months—these maternal antibodies can interfere with the vaccine and the child may not develop good protective immunity. By about 12 months, maternal antibodies have decreased enough and the immune system can respond reliably, producing protective antibodies. That’s why the first dose is typically given at around 12 months (1 year). Delaying beyond this leaves children unprotected during a vulnerable period, and giving it earlier than 12 months isn’t reliably effective.