Measles cases cross the 1,000 mark: How to protect yourself and others
May 12, 2025
For just the second time in 30 years, a measles outbreak in the U.S. has reached more than 1,000 cases, with the majority recorded in West Texas. As cases continue to rise – as of June 5, 2025, a total of 1,168 confirmed measles cases were reported by the Centers for Disease Control and Prevention (CDC) in 34 states – many people across the country are wondering about their level of protection from the highly contagious virus.
The good news is that most Americans have received the measles-mumps-rubella (MMR) vaccine, which is commonly administered to children when they are young, usually before attending school. The MMR vaccine is the safest, most effective tool to protect against the measles virus – a single dose is 93% effective; two doses are 97% effective.
In fact, measles was declared eliminated in the U.S. in 2000 as the level of immunity caused cases to largely disappear.
However, declining vaccination rates in recent years have led to a resurgence of cases, most likely precipitated by travelers who carried the virus to the U.S. from another country where vaccinations are significantly lower.
In Texas, kindergarten vaccination rates fell to 94.3% in 2023, below the 95% threshold needed for herd immunity, and rates in some communities are reportedly below 90%. This underscores the urgent need for improved vaccine accessibility and vaccination rates to curb transmission, said Saad Omer, M.P.H., Ph.D., M.B.B.S., the inaugural Dean of UT Southwestern’s Peter O’Donnell Jr. School of Public Health.
“Public health is all about prevention, and the vaccine is like a public health insurance policy,” said Dr. Omer, who is a nationally recognized expert on vaccine efficacy. “In general, Texas immunization rates have been high. But there are pockets of vulnerability in the state, and the country, where the local immunization rates are lower than the overall average. And that’s where increasing vaccination rates can help stem the tide.”
About 95% of the confirmed measles cases in this year’s outbreak have been in individuals who are not vaccinated or whose vaccination status is unknown, according to the CDC.
For anyone who is unsure if they are protected against measles, Dr. Omer recommends consulting vaccine guidance from the CDC or talking to their doctor. Below, he provides answers to some frequently asked questions about measles immunity, vaccination, travel during an outbreak, and more.
How do I know if I have immunity to measles?
According to the CDC, evidence of immunity is determined in one of four ways:
- Written documentation of adequate vaccines for measles, mumps, and rubella
- Laboratory evidence of immunity (a blood test to detect measles-specific antibodies)
- Laboratory confirmation that you had the disease
- Birth before 1957, when the virus was prevalent enough that most people were exposed to it and developed antibodies.
Do I need a booster now?
If you received two doses of the MMR vaccine, you are protected.
If you were born after 1957 and received one dose of the vaccine, you are also considered protected. The CDC recently recommended that some individuals with one dose who are living in or traveling to areas in the U.S. with ongoing community-wide measles transmission should consider getting a second dose for maximum protection.
When should I get the vaccine?
The MMR vaccine schedule in the U.S. is as follows:
- Younger children are recommended to receive two doses of the MMR vaccine. First dose at 12-15 months; second dose at 4-6 years.
- Older children, adolescents, and adults (including health care personnel) without evidence of immunity should receive 1 or 2 doses of MMR, at least 28 days apart,
- For unvaccinated individuals exposed to measles, the MMR vaccine should be administered within 72 hours. In some cases, immunoglobulin may be given as a medication within six days to prevent or reduce severity of the virus.
What if I’m traveling to an area where there is a measles outbreak?
An active outbreak of measles is defined as three or more cases because it is such a contagious respiratory virus – much more contagious than flu, COVID-19, or even Ebola.
If you are traveling to an area where there is a measles outbreak and you are vaccinated with two doses, you are protected. In Texas, the Department of State Health Services recommends the following accelerated schedule for affected areas if you are unvaccinated:
- Infants 6-11 months can receive an early (infant) dose of MMR vaccine; subsequent doses should follow CDC-recommended schedule.
- Unvaccinated children older than 12 months should receive one dose immediately, and a 2nd dose at least 28 days later. Children older than 12 months who have received a prior dose should receive an early second dose at least 28 days after first.
- Teenagers and adults previously vaccinated with one dose should receive a second dose; those without evidence of immunity should receive one dose immediately and follow with second dose at least 28 days later.
Can adults get measles?
While mostly associated with children, adults also contract measles. According to the CDC, as of June 5, 2025, 33% of the 1,168 cases in the United States this year were adults 20 or older.
What are the symptoms of measles, and can it be deadly?
The typical symptoms are cough, fatigue, fever, watery eyes, and rash, but measles can also cause severe complications including pneumonia and encephalitis. Long-term consequences include infertility in males and a rare but fatal progressive neurological condition called subacute sclerosing panencephalitis (SSPE), which can be fatal. Young children, pregnant women, and immunocompromised individuals are at higher risk for severe complications. Three people (two children and one adult) have died during the 2025 outbreak as of June 5.
If I got the vaccine in the 1960s, do I need to get revaccinated?
Determining personal immunity can be difficult for adults who grew up in the 1960s, when the measles vaccine first became available. If you do not have your vaccination records or documentation of measles immunity, you should consider getting vaccinated now to protect yourself. There is no harm in getting another dose of MMR vaccine if you may already be immune.
Less than 1 million people between 1963 and 1967 received an inactivated (or “killed”) version of the measles vaccine – an early formulation that is not as effective as the one used today because it contains a weakened (attenuated) form of the virus. The CDC recommends getting a dose of the live attenuated vaccine for anyone vaccinated before 1968 who received either the inactivated vaccine or a measles vaccine of unknown type.
Could I still get measles if I’m fully vaccinated?
People who get two doses of measles vaccine are 97% protected, which means about 3 out of 100 might get measles, but they are more likely to have a milder form of the illness and are less likely to spread the disease to others. No vaccines offer 100% effectiveness, but the MMR vaccine is extremely protective and usually offers lifelong immunity.
When was the last time the U.S. had more than 1,000 confirmed measles cases?
More than 1,200 cases were recorded in 2019 in New York City, but swift vaccination efforts in that community helped contain it. The 2025 measles outbreak, which began in West Texas, has now expanded, and cases have been reported in more than 30 states in the U.S.
