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Whenever news of a measles outbreak hits, it’s totally valid to wonder about your own susceptibility to the virus. Even if you were vaccinated as a kid, is there a chance you need a measles booster as an adult? The most recent event that’s resurfaced this question: a measles outbreak in west Texas, where 90 cases have been reported since January 2025. Of those cases, five people are vaccinated against the disease, and the rest are either unvaccinated or have an unknown vaccination status. Sixteen people have been hospitalized. The Texas Department of State Health Services is anticipating more cases in the outbreak area and surrounding communities considering how contagious the disease is.
This…shouldn’t be happening. In 2000, measles was officially “eliminated” from the United States, thanks to widespread, effective vaccination. But, as we’ve seen more and more, the virus still pops up from time to time. (For example, last winter, measles cases were reported in Philadelphia, Washington state, New Jersey, and Georgia.) Given that measles spreads very easily and can cause gnarly symptoms (and long-term complications), it’s understandable if you have questions about how to stay safe. Booster vaccines are common practice for viral illnesses like the flu and COVID-19, so should you consider the same for measles? We asked infectious disease experts to share everything you need to know.
First, here’s how the measles vaccine works.
In the US, the measles vaccine also protects against mumps and rubella, and is known as the MMR vaccine. (There’s also an option that includes chickenpox, or varicella.) It’s a live attenuated virus vaccine, which means it contains weakened viruses that spark an immune response so the body is primed to protect against future exposures. This can trigger few (if any) symptoms before your body eradicates the viruses. During this process, your immune system works hard to produce specific infection-fighting immune cells and proteins, so if you happen to come across the virus that causes measles in the future, your body remembers how to respond to it swiftly.
“This is a remarkably effective vaccine,” William Schaffner, MD, an infectious disease specialist and professor of preventive medicine at the Vanderbilt University School of Medicine in Nashville, tells SELF. Just one dose of the shot is 93% effective against measles, while the recommended two doses offer 97% protection.
The MMR vaccine should have been baked into your childhood immunization schedule. (If you were vaccinated in the 1960s, there’s a chance you received an inactivated version that is not effective, and should get the live attenuated version.) It’s recommended that kids get the first dose between the ages of 12 to 15 months and the second between the ages of four and six years. “If you attend public school in the US, you typically need to have had the MMR vaccine,” Dr. Schaffner says. However, some private schools do not require the MMR vaccine, and depending on the state you live in, there may be religious or philosophical exemptions for vaccines (all 50 states allow for medical-related exemptions). So it’s possible to reach adulthood without ever receiving it, he notes.
Can measles immunity wane over time?
It’s a fair question—and one that we don’t have as much data on as we’d like, says Tony Moody, MD, a professor in the department of pediatrics, division of infectious diseases and professor in the department of integrative immunobiology at Duke University Medical Center. From the research we do have on the subject of waning vaccine immunity, it seems that measles immunity, specifically, is quite persistent.
“As a vaccine, it’s super effective,” Dr. Moody tells SELF. “We think that once you’ve got immunity, it probably does last for the rest of your life.” But there are some potential reasons immunity may weaken a tad over time. First, most of us have had a total lack of exposure to the measles virus since vaccine coverage became widespread. “We know from things like chickenpox that when you are exposed, you get a little boost to keep up your immunity,” Dr. Moody explains. “Now that we don’t have as much measles circulating in the country, that might not happen.” To be clear, this doesn’t mean your immunity is going to eventually disappear, just that we may not be getting that additional exposure-based immunity anymore.
Also, immune function in general declines with age, Dr. Moody says. The immune system just doesn’t stay as strong or efficient as we get older, which is part of why elderly populations are at a higher risk of getting seriously ill from things like RSV, COVID-19, and the flu.
Can you test for measles immunity?
In short, yes. An antibody titer test is a blood test that can check your immunity to the measles virus. It’s available via your doctor or a technician at a pharmacy like CVS, though you may need to pay out of pocket for it.
However, Dr. Moody notes that antibodies are only one part of the picture. “We don’t really think the antibodies themselves are protecting you against measles,” he says. “It’s probably a T-cell response.” T-cells are white blood cells that fight germs and protect you from disease. When you have the measles or get the vaccine, for example, a number of these cells detect the virus and then adapt. Their sole purpose from that moment forward is to remember that specific virus and fight it off if you’re exposed to it again in the future. T-cells also help direct another type of immune cell (B-cells) to create antibodies, which are proteins that bind to the antigen and neutralize it, or prevent it from invading healthy cells and causing infection.
“The antibody test is a nice surrogate for [overall immunity], but it doesn’t tell you if the antibodies have gone away that the T-cell response has too,” Dr. Moody explains. However, testing for T-cells is harder to do and roll out at scale, he adds, so it’s not typically done for this purpose.
So yes, you could go and get a measles antibody test. But “it’s sometimes easier to just get the vaccine and be done with it,” says Dr. Moody.
How to know if you might need a measles booster
Hearing about an outbreak can be nerve-wracking, but as long as you are up-to-date on your recommended shots, experts say you should feel confident that you’re well protected.
Overall, "it’s extraordinarily rare” to get the measles if you've been fully vaccinated, Thomas Russo, MD, chief of the division of infectious diseases at the University at Buffalo in New York, tells SELF. The Centers for Disease Control and Prevention estimates that about 3 in 100 people who receive two doses of the MMR vaccine will still get sick if they’re exposed to the virus. (Again, immunity isn’t a perfect science!) Fully vaccinated people who become infected usually have a milder case, and are much less likely to spread measles to others.
That said, it is important to be sure you’re fully vaccinated. “Fully” is the keyword here: If you weren’t vaccinated but had measles as a kid, Dr. Russo says it’s “presumed” that you have immunity against the virus—but most health care providers still recommend getting the vaccine, just in case. If you had just one dose of the shot as a kid, you don’t necessarily need a second dose as an adult—but it also doesn’t hurt, especially if you travel a lot or work in health care or education and have a higher likelihood of exposure. “The safest course is to get two doses,” Dr. Russo says.
Ultimately, here’s no harm in getting an MMR booster if your doctor thinks it makes sense for you and your particular circumstances. “Everybody has to judge their own risk personally and talk to their physician about it,” Dr. Moody says. Is a booster necessary for most people? Probably not. But if you live in or are going to travel to an area where there’s an outbreak or low vaccination rates and you’re concerned, there’s nothing wrong with getting another one just in case, he says. “They’re very effective and very, very safe.”
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