Pediatric vaccines Q&A with Professor Dr. Margaret Quinn

Q: Tell me in simple terms what is the MMR vaccine?

A: MMR is one vaccine that protects against three separate viral illnesses: measles, mumps and rubella. It is a live, weakened vaccine that teaches the immune system to recognize those viruses and fight them without causing the diseases themselves.

We have over 50 years of experience with this vaccine. The combined MMR vaccine was first licensed in the United States in 1971, and today's vaccines have an extensive history of safety and effectiveness. For measles specifically, one dose is about 93% effective and two doses are about 97% effective, according to the CDC. 

Q: What age should children get the MMR?

A: For most children, the first MMR vaccine is given between 12 and 15 months of age, and the second dose is given between 4 and 6 years of age—[typically] before they start kindergarten.

Q: Why are MMR vaccines important?

A: Measles is one of the most contagious infections we know. It can cause pneumonia, inflammation of the brain, hospitalization and, in rare cases, death.

Rubella is particularly dangerous during pregnancy, because it can cause miscarriage or severe congenital abnormalities in the developing [fetus.] Mumps can cause complications such as meningitis, hearing loss and inflammation of the testes or ovaries which can cause sterility.

Vaccinating one child also helps protect infants who are too young to be routinely vaccinated, pregnant women, and people whose immune systems prevent them from receiving a live vaccine.

This is both individual protection and community protection.

Q: What vaccination schedule should parents and children follow from birth through age 12?

A: I recommend that families discuss this with their pediatric provider and consider following the 2026 American Academy of Pediatrics  childhood and adolescent immunization schedule. This evidence-based schedule is supported by numerous national medical organizations, including the National Association of Pediatric Nurse Practitioners. (HealthyChildren.org)

Not every child receives every vaccine at exactly the same visit. Medical conditions, previous doses, travel and other circumstances can modify the schedule.  There are many resources available to parents, and they should check with their primary care or pediatric provider to ask any questions about the schedule.

Q: Do tweens or teens require MMR boosters?

A: Not routinely.  If a tween or teenager received two appropriately timed MMR doses as a child, we do not routinely give another MMR booster simply because they have reached adolescence.

However, if they have received only one dose, have no vaccination documentation, or are otherwise not considered immune, we catch them up. Two doses should be separated by at least 28 days.

There are also certain outbreak situations—particularly involving mumps—where public health authorities may recommend an additional dose for people at increased risk.

Q: What about adults? Should adults who previously received an MMR ever get a booster?

A: Most people born before 1957 are immune to measles.  Adults vaccinated between 1963 and 1968 should check their immunization status to determine whether they have the most current formulation. Most born after 1968 have received the current vaccination formula and are protected. Certain adults may need a booster.  Anyone living in a group setting, healthcare personnel, or international travelers may need a booster.

There are some adults for whom vaccination history becomes especially important: healthcare workers, international travelers, college students, people exposed during an outbreak, and adults who are unsure whether they were adequately vaccinated.

I would not tell an appropriately vaccinated adult to simply go out and get another MMR "just in case." I would look at age, vaccine records, risk factors, travel and potential exposure.

This Q&A has been edited for length and clarity.

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