With a growing measles outbreak across the United States, the question of whether adults need a vaccine booster is more relevant than ever.
Here are some key facts about who needs a booster — and why it matters.
Measles is spreading
As of April 2025, there have been 607 confirmed measles cases in the U.S.
A staggering 97 % of these occurred in individuals who were either unvaccinated or whose vaccination status is unknown. That makes vaccination more critical than ever.
The MMR vaccine is your best protection
The MMR vaccine doesn’t just protect against measles — it also protects against mumps and rubella.
Two doses provide about 97 % protection against measles, while one dose offers 93%.
A booster is like a “reminder” for your immune system
A vaccine booster strengthens your immune memory, reminding your body to stay alert against the measles virus.
It helps ensure your protection remains strong, especially during outbreaks.
The vaccine has improved since 1963
The first measles vaccine appeared in 1963, but it was a weaker formulation.
People vaccinated between 1963 and 1967 may have received an inactivated version that provides less protection, making a booster worth considering.
Born before 1957?
People born before 1957 are assumed to have natural immunity because they likely contracted measles during childhood.
Still, a blood test can confirm if you’re truly protected.
You can check your immunity with a blood test
A simple IgG blood test can determine if you have enough antibodies to measles.
If you’re unsure about your vaccine history, this test can provide peace of mind and clarity.
These people might need a booster
You might need a booster, if you only received one dose as a child, got the inactivated vaccine in the ’60s, belong to a high-risk group, or test low for antibodies.
The specifics of your medical history and lifestyle matter.
Some adults should receive two MMR doses
Adults at higher risk of exposure — including healthcare workers, international travelers, and college students — should have two MMR doses in adulthood if not previously vaccinated.
Not everyone can safely get the MMR vaccine
The MMR vaccine is a live attenuated virus vaccine.
Those with severe allergies, certain immune disorders, or who are undergoing immunosuppressive therapy may not be able to receive it safely and should consult their physician.
Always consult your doctor first
While general guidelines exist, your personal health circumstances should guide your vaccine decisions.
Talk with your primary care provider to assess risks and benefits before getting a booster.
This article is based on information from Medicalnewstoday.com.