How we lost our collective memory of epidemics

Fact Check: How Long Does Protection From The Measles Vaccines Last?

Does the MMR vaccine's protection against measles change over time? MNT asks experts. Image credit: Raquel Natalicchio/Houston Chronicle via Getty Images.This article originally appeared on Medical News Today

As the measles outbreak expands across the United States, public health measures have increased to slow the spread of the disease.

Many people have expressed worries about whether vitamin A can help prevent infection, whether they need a measles vaccine booster, or if measles can have long-term negative consequences on health.

The latest question to fuel concern has been about how long the protection of the measles vaccine lasts, driven by U.S. Secretary of Health and Human Services Robert F. Kennedy Jr.'s recent comments.

Medical News Today speaks to experts to fact-check some prominent claims about measles and the MMR vaccine.

United States Secretary of Health and Human Services RFK Jr. Recently joined other experts and expert medical bodies in endorsing the MMR (measles, mumps and rubella) vaccine as the most effective way to ensure protection against measles.

His comments came in an X post in what many people described as a surprise due to his past skepticism toward vaccine safety and effectiveness.

However, shortly after he shared this message, the secretary was interviewed on CBS News, where he alluded to ebbing immunity from vaccines and other ways to treat people who choose not to get vaccinated.

"We're always going to have measles, no matter what happens, as the vaccine wanes very quickly," Kennedy had said.

So far, there are no other preventive treatments against measles other than the MMR vaccine. Vitamin A, for example, is also only given to lessen the severity of symptoms after a person has contracted measles.

Many medical professionals and the public have been left confused and worried about these comments. To fact-check these claims, Medical News Today spoke to two experts: David Cutler, MD, board certified family medicine physician at Providence Saint John's Health Center in Santa Monica, CA, and Gina Posner, MD, board certified pediatrician at MemorialCare Medical Group in Fountain Valley, CA.

Cutler said:

"It is both disappointing and dangerous that there is so much conflicting and incorrect information from the current U.S. Secretary of Health and Human Services regarding measles and the MMR vaccine. Part of the problem is that infectious diseases, immunity and vaccines are all complicated. But there is also the problem of misleading and absolutely false information coming from a previously trusted government source. So, what is true?"

Claim: The protection of the measles vaccine wanes quickly

Fact: Two doses of the MMR measles vaccine provide lifetime protection.

Referring to RFK Jr.'s recent comments, Posner said it wasn't true that the vaccine's protection waned quickly.

"Most people get the vaccine as young kids (age 1 and 4) and have it lifelong," she said.

Cutler said that in the case of the MMR vaccine for measles, the immunity provided by the innoculation will last a lifetime. However, he reminded of exceptions when it comes to two other infections.

"Sometimes, viruses will change, so the immunity you get from the vaccine may not protect you against future variants of the virus; this is true for influenza and COVID. But the measles virus has been unchanged for centuries," he said.

Is the measles vaccine safe and effective?

Cutler reiterated that measles was eradicated in the U.S. In 2000 thanks to the MMR vaccine, which goes to show its effectiveness and safety.

"However, because there are rare side effects and a very small percentage of people who do not achieve full immunity after vaccination, it is possible that some people will weaponize this uncertainty to claim the danger and ineffectiveness of the MMR vaccine," he added.

"In general, a single dose of the MMR vaccine is 93% effective. Getting a second dose makes it 97% effective. Since there are currently a fair number of unvaccinated people, it is worthwhile for children and other high risk individuals to get two vaccines," Cutler said.

"However, a single vaccine is adequate for adults who have not been previously vaccinated. The value of the second vaccine depends on your individual risk and how much measles is out there," he added.

Why herd immunity is crucial

Posner reiterated that 97% of people get full immunity after the second dose of the vaccine.

"That still does leave 3% as non-responders which is why we need herd immunity to protect both those people and ones who really can't have it," she said.

Cutler underscored the importance of public health and said that for measles spread to be unlikely, approximately 95% of the community will have need to have been vaccinated.

"Epidemiologists estimate that if 95% of people in a community are vaccinated, then there will not be enough susceptible people to prolong an outbreak. In addition to vaccines, isolating [people with infections] will help prevent the spread of the disease," he said.

Claim: I need to get a measles vaccine booster

Fact check: False, for the majority of people. If you have received two doses of the MMR vaccine, you will have lifelong protection. However, some people — such as people born before 1957, people vaccinated with an inactivated measles vaccine before 1968, and immunocompromised individuals — may require another dose if they are found to not have immunity.

"Some people get tested for immunity later in life (like pregnant people) and if they are found not to have immunity, once they give birth, they are told to get another dose (or two)," Posner added to highlight exceptions.

"If [a] virus mutates, then a different strain needs to be given with a new vaccine. Also, sometimes we don't develop as strong of an immune reaction to a certain vaccine and then we must repeat it every so often (like our Tdap needing to be done every 10 years). MMR is not one of those. It is given at age 1 and 4 typically and that is it."— Gina Posner, MD

Cutler said some infectious diseases may require boosters periodically but that measles was not one of them.

"Another reason you may need a booster vaccine is if your immunity wanes with time. This is true for tetanus shots. That is why tetanus boosters are recommended every 10 years. But this is not true for measles. Once immune from either the vaccine or prior infection, your measles immunity persists," he said.

Claim: There is no need to get vaccinated against measles

Fact check: The only tested and effective way a person can protect themselves against measles is via the MMR vaccine. There are no other effective preventive treatments for measles. However, vitamin A can be used to lessen the severity of disease in people who are already experiencing a measles infection.

"Severe cases of measles can be treated with two doses of vitamin A to prevent complications of the disease. However, the risks of high doses of vitamin A need to be considered prior to initiating this therapy. There is no evidence that vitamin A or any dietary supplement prevents acquiring measles infection," Cutler said.

"The true value of the vaccine can only be achieved when very high percentages of people are vaccinated, even when disease risk is low. People acting in their own self-interest by avoiding vaccines puts us all at greater risk. Adequate funding, staffing, and resourcing of public health efforts are essential for disseminating accurate information and providing services to protect everyone from diseases like measles."— David Cutler, MD

View the original article on Medical News Today

Should Babies Get The Measles Vaccine Before Age 1?

As the measles outbreak expands rapidly across the U.S., parents of infants face an agonizing dilemma: Is it safe to take my baby into public spaces?

For decades, American parents have relied on high levels of vaccination in the community to keep their babies safe from measles from the time they are born until they can get the measles, mumps, and rubella (MMR) vaccine at 12 months of age.

In 2025, with the virus now spreading and at least one child dead, should parents vaccinate their baby before they are 1 year old?

How Big Is the Current Measles Outbreak?

Since the beginning of 2025, an outbreak in West Texas has led to measles outbreaks across the country. As of March 27, 2025, CDC reports that there are 483 confirmed cases in 19 states. The actual number of ill people may be substantially higher, because CDC is only reporting cases that are confirmed by a laboratory test or by an epidemiologic link to a laboratory-confirmed case.

Of the 483 confirmed cases, 70 have been sick enough to require hospitalization. Most troubling, a child under the age of 5 has died—the first measles-related death reported in the U.S. Since 2015.

Measles is one of the most contagious diseases on earth, transmitted through the air by people who may not even have symptoms yet. Once measles enters a community with low vaccination coverage, it spreads rapidly, especially in places like daycares, schools, airports, and doctors' offices.

Child with classic measles rash.

Source: Dr. Philip Nader/CDC

Does Measles Cause Long-Term Damage?

Measles is not simply a rash and fever. It can lead to pneumonia, deafness, blindness, and acute encephalitis, a life-threatening inflammation of the brain.

Even children who appear to recover from the illness can suffer long-term complications, such as encephalitis, weeks to months after infection or, in children infected before age 2, a deadly condition called subacute sclerosing panencephalitis (SSPE) 10 years after infection.

Almost all people who have measles develop prolonged suppression of their immune system, putting them at risk of infections from other bacteria and viruses, even those they were previously vaccinated against.

There are no drugs to treat measles, which is why vaccination is so important.

Why Is the First Measles Shot Given at 12 Months?

The current U.S. Vaccine schedule calls for the first MMR dose to be given no sooner than 12 months of age and up to 15 months of age. It then calls for a second dose between the ages of 4 and 6. This schedule is based on extensive research on the immunology of the vaccine and detailed analysis of real-world data both here in the U.S. And in other countries.

Infants carry antibodies from their mother that help protect them during their first few months of life. The ability of these antibodies to protect a baby against measles fades over the first 12 months, but there are often just enough antibodies to interfere with the vaccine. These antibodies may prevent the infant's immune system from mounting a strong response if they are vaccinated before 12 months. That's why early vaccination was not recommended in the past.

Historically, experts believed that a single dose given at 1 year of age provided lifelong protection. But after large outbreaks occurred in vaccinated school-aged children during the late 1980s and early 1990s, researchers discovered that about 5 percent of children failed to respond to the first dose. That's when public health experts began recommending a second dose between the ages of 4 and 6 to ensure long-term immunity.

Is Early Vaccination Safe and Effective?

When traveling with a baby to an area with high rates of measles, CDC and World Health Organization (WHO) recommend an early dose of MMR vaccine as early as 6 months of age. This is standard practice in low- and middle-income countries where measles is common, and multiple studies have confirmed its safety.

What's different about an early dose is that public health agencies do not count this early vaccine as part of the required two-dose series. Immunity from this early dose may not last. Therefore, babies who receive an early dose must still get two additional doses—one at 12 to 15 months and another at 4 to 6 years. Fortunately, receiving additional doses is safe.

Can I Check if My Baby Is Immune After an Early Measles Shot?

Some infants vaccinated before 12 months do achieve long-term protection, especially if:

Maternal antibody levels are low

The vaccine was given at 9 to 11 months of age

There are no widely available or affordable tests to identify whether a baby has developed a strong enough response to the first dose that they do not need additional doses after 12 months of age. Tests to assess immune response—such as for high-avidity antibodies or T-cell activation—are available only in research settings and are not reliable enough for guiding clinical decisions. It is safest, therefore, to receive the standard two doses after the baby is 12 months old.

When to Get an Early Measles Shot?

Here's why you may want to consider vaccinating your baby for measles before they are 12 months old.

Geographic location and exposure risk: Are there confirmed cases of measles in your city or state? Are you traveling to a place with an outbreak?

Community vaccination coverage: Does your daycare, school, or local community have high rates of vaccination? Is your baby routinely spending time with unvaccinated children or adults?

Infant's age and health: Infants 6 to 11 months old are eligible for early vaccination. Babies younger than 6 months are not, and their best protection is to avoid high-risk settings.

If you and your pediatrician agree that an early dose is appropriate, you should also discuss plans for completing the full vaccine series.

How Will the Measles Outbreak End?

Measles is preventable. We have a safe, highly effective vaccine. The reason this virus is spreading in the U.S. In 2025 is that not enough people are getting vaccinated.

My hope is that this outbreak ends quickly as more parents vaccinate on time and more unvaccinated people catch up. Until then, if you're the parent of a baby under 12 months old and you live in or are traveling to an area with measles cases, consider getting your child an early dose of measles vaccine.

An early dose may not have been part of your original plan— but given what we're facing now, it may be the right choice.

Can You Get The Measles Vaccine While Pregnant?

Feb. 28, 2025

Updated Apr. 6, 2025 at 10:26 a.M. CDT

2 min. Read

Measles, mumps and rubella vaccines sit in a cooler at the Rockland County Health Department in Pomona, N.Y.

Update:

10:25 a.M. April 6, 2025: This story was updated with the latest case numbers and a new death.

Texas' measles outbreak reached nearly 500 cases on Friday.

Measles is one of the most contagious viruses in the world and spreads mostly among unvaccinated people. Two school-age children have died.

Dr. Lara Johnson, a pediatrician and the chief medical officer at Covenant Children's Hospital in Lubbock, said she has also seen several cases of measles in pregnant women, who are at higher risk of complications if they catch the virus.

With two doses being 97% effective, doctors recommend the measles-mumps-rubella vaccine to anyone who wants to protect themselves from infection. But does that advice apply if you're expecting?

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Related:Second unvaccinated child dies from measles in West Texas outbreak

For safety reasons, experts say no.

According to the Centers for Disease Control and Prevention, you should wait to get the MMR vaccine until after you are no longer pregnant, and should also avoid getting pregnant for at least one month after getting the vaccine.

Here's why: The MMR vaccine is a live vaccine, meaning it contains a mixture of weakened measles, mumps, and rubella viruses, which helps the body build antibodies that protect against the viruses in the future.

Related:Live: Track measles cases during West Texas outbreak with these graphics

There is no evidence to suggest that the MMR vaccine itself increases the risk of birth defects, but health officials say the fact it is a live vaccine does come with a "theoretical risk" to an unborn baby. The risk is namely a rubella infection that can lead to "congenital rubella syndrome," which can cause birth defects and neurodevelopmental problems.

The MMR vaccine can, however, be given to people who are breastfeeding, according to the CDC, which recommends consulting a health care provider before scheduling your shot.

Jamie Landers is a breaking news reporter at The Dallas Morning News. She is a graduate of The Walter Cronkite School of Journalism and Mass Communication in Phoenix, where she studied journalism and political science. Jamie previously reported for The Arizona Republic and Arizona PBS.

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