Expert Q&A: Should you get a measles vaccine booster?

• With an ongoing measles outbreak across the United States, some questions about the best protective measures have emerged.
• Health and Human Services Secretary Robert F. Kennedy Jr. has joined other experts and expert medical bodies in endorsing measles vaccination as the best way to ensure protection against infection.
• However, depending on when and what type of measles vaccine a person has had, they may need to get a vaccine booster to ensure continued protection.

According to official data from the Centers for Disease Control and Prevention (CDC), as of April 3, 2025, there have been a total of 607 confirmed casesTrusted Source of measles across the United States though the actual numbers may be higher.

Of these, 97% of cases occurred in individuals who were either unvaccinated or whose vaccination status remains unknown.

The consensus remains that vaccination is the best way to protect against measles. United States Health and Human Services Secretary Robert F. Kennedy Jr. has been the latest official to endorse vaccination as “The most effective way to prevent the spread of measles.” 

The vaccine currently in use, referred to as the MMR vaccine, actually confers protection against mumps and rubella as well as measles, hence the abbreviation. Kennedy Jr. has also instructed the CDC to “supply pharmacies and Texas-run clinics with needed MMR vaccines and other medicines and medical supplies.”

Typically, if following recommendations, children will receive two dosesTrusted Source of the MMR vaccine — one at 12–15 months old and another at 4–6 years old — which confer 97% protection against measles.

Receiving a single dose of the vaccine confers 93% protection against measles.

People who have had MMR vaccination are protected for life. However, the current vaccine, developed in 1971Trusted Source, is an improved formula compared to previous vaccinations.

This raises the question: Should people who have already received a measles vaccine at any point receive a booster to ensure continued immunity?

GMHCN has asked David Cutler, MD, a board certified family medicine physician at Providence Saint John’s Health Center in Santa Monica, CA, to help answer these and other related questions.

Cutler pointed out that “there will remain some uncertainty about the risk posed by measles to any one individual due to several factors.” 

• how common measles infections are in their community
• to what extent the individual and their community have achieved immunity to measles either by prior infection or through vaccination
• how vulnerable the individual is to measles infection.

First of all, what is a vaccine booster, exactly, and what does it do?

“A booster vaccine, just like an initial vaccine, will initiate or augment a person’s immune protection against measles,” Cutler explained.

It acts as a “reminder” to the body’s immune system to “watch out” for a specific pathogen that it has already become “trained” to fight against through the initial vaccination.

The first MMR vaccine became available in the U.S. in 1963Trusted Source but, compared to current versions of the vaccine, it had a “weaker” formulation.

So, if you are an adult who was vaccinated in childhood when exactly you got the measles vaccine may determine whether or not you would benefit from a booster. Other factors are at play, too, as Cutler noted.