What to know about measles and the MMR vaccine

Measles was once eliminated in the U.S., but cases are now increasing. In early 2025, a measles outbreak was reported in Texas, with cases continuing to spread. Health officials have linked the outbreak to low vaccination rates, raising concerns about the potential for further spread.

Carla Garcia Carreno, M.D., Medical Director of Infection Prevention and Control at Children’s Medical Center Plano, shares what you need to know about the measles, how the vaccine works and ways to keep your child safe.

What is measles?

Measles is a viral infection that can cause a red, blotchy rash, fever, cough and a runny nose. This highly contagious condition can also lead to serious and even life-threatening complications, such as pneumonia and encephalitis.

What are the signs and symptoms of measles?

Measles symptoms typically appear 7 to 14 days after exposure (but can present up to 21 days after contact with someone with measles). These symptoms include:

• High fever

• Cough

• Runny nose

• Red, watery eyes

• Koplik spots (small white spots inside the mouth surrounded by localized redness) which may appear before the rash

• A red rash that starts on the face and spreads to the rest of the body

"The rash typically appears after day three or so of the fever," Dr. Carreno says.

What are possible complications of measles?

Complications from measles can be severe, especially in young children, pregnant women and individuals with weakened immune systems. Serious complications include pneumonia, brain swelling (encephalitis), and, in rare cases, death.

A rare but fatal complication can be seen around 10 years after acute measles, the Subacute Sclerosing Panencephalitis (SSPE), which can occur in 4 to 11 of 100,000 cases. This fatal form of encephalitis can present with seizures, loss of neurologic functions, and has a 95% mortality rate.

Another complication is the blunting of the cellular immune response after measles. In other words, it weakens the immune system’s response to defend against certain infections.

How does measles spread?

Measles is spread by coming into contact with someone who has the virus. When someone with the condition coughs, sneezes or talks, this can spread the virus onto nearby people, air and surfaces. The virus can travel more than six feet and live for up to two hours in the air after an infected person leaves the room. According to the Centers for Disease Control and Prevention (CDC), if one person has measles, 90% of unvaccinated individuals in close contact will also contract the disease.

A person with measles can be contagious from four days before the onset of the rash until four days after the rash appears. This means individuals can spread the virus before they even realize they are sick, increasing the risk of transmission in communities with low vaccination rates.

Because measles can be prevented with the measles, mumps and rubella (MMR) vaccination, most children are now protected from contracting the virus.

"However, as doctors, we're always aware that we could present with a case of measles in the community," Dr. Carreno says. "So, we always need to have the high index of suspicion if a patient presents with symptoms."

How are measles treated?

There is no specific antiviral treatment for measles. Management focuses on relieving symptoms and preventing complications. Treatment may include:

• Rest and plenty of fluids

• Fever reducers such as acetaminophen (Tylenol) or ibuprofen (Advil)

• Vitamin A supplements, which have been shown to reduce measles severity in children (a deficiency in Vitamin A can be associated with a more severe course of the disease)

• Monitoring for complications, such as pneumonia or encephalitis, which require immediate medical attention

Contact your pediatrician if you suspect your child may have been exposed to measles.

How does the measles vaccine work?

When a virus or bacteria strikes, the body creates antibodies to fight off the infection. Each antibody is specific to that infection. Once the body has made these antibodies, it can recognize and fight off the infection in the future, even before the symptoms show.

Vaccines are a safe way to expose the body to the virus without getting the disease. They allow the body to have a natural immunity to the condition without the risk of serious complications from the natural disease.

The MMR vaccine is a 3-in-1 immunization that can protect your child from measles, mumps and rubella. The injection contains weakened strains of each of these viruses. Your body's immune system recognizes the viruses and creates antibodies to fight the weakened strains.

When should kids get the measles vaccine?

Children should receive two doses of the MMR vaccine at the following times:

• The first dose at 12 to 15 months of age

• The second dose at 4 to 6 years of age

The vaccine provides lifelong protection for most people.

How do I protect a baby who is too young to receive the vaccine?

Infants under 12 months are too young to receive the MMR vaccine, so it is important to:

• Ensure all family members and caregivers are vaccinated

• Avoid exposing infants to crowded areas where measles may spread

• Keep babies away from individuals who are sick or unvaccinated

Be sure to talk to your pediatrician about a recommended vaccine schedule if your baby is under 12 months and will be traveling with you to an endemic area, a country with measles circulation or in case of a local outbreak of measles.

Similarly, if your child or any other person in the household cannot receive the vaccine because of a weakened immune system, protecting those surrounding the vulnerable person is essential.

Should adults get a measles booster shot?

Most adults who have received a measles vaccine do not require a booster shot. Adults who were immunized between 1963-1967 may consider getting a booster as the vaccine during those years was not as effective as the current vaccine. Adults who are unsure of their vaccination status should talk to their doctor about getting a blood test or an additional dose of the MMR vaccine.

Are there side effects from the measles vaccine?

Most children do not experience any side effects from the MMR vaccine. The most common side effects are typically mild, and can include a rash, fever or temporary soreness. Some parents have concerns that the MMR vaccine is linked to autism. However, there is no scientific evidence that supports that claim.

Can you get measles if you've been vaccinated?

If your child received the MMR vaccine, he or she should not get the illness if they come into contact with a person who has measles. In rare cases, about 3% of vaccinated individuals may still be at risk of infection, though their symptoms tend to be milder. In addition, young children who have not had their second dose of the MMR vaccine are at higher risk of contracting the disease.

As the MMR vaccine becomes more common worldwide, measles rates have declined across the globe, making it less likely to be exposed to a person with the measles. Vaccinating your child against the measles can help ensure your family and community is protected against the disease.

Get vaccinated

​The best way to prevent measles and its complications is through vaccination. If you are unsure whether your child is up to date on their MMR vaccine, contact your pediatrician today.

Learn more about vaccines and how they can protect your child from serious illnesses.