The MMR vaccine (sometimes offered with the varicella vaccine and called MMRV) is a key component of your child’s immunization schedule.
Here’s a look at the diseases this vaccine protects against, plus why these shots are so important.
What is the MMR vaccine?
The MMR vaccine contains weakened measles (M), mumps (M), and rubella (R) viruses.
“This vaccine protects children from three serious diseases that can make kids very ill, requiring hospitalization, and can have long-term or life-threatening complications such as pneumonia, meningitis, encephalitis, and deafness,” says Lauren Crosby, M.D., a pediatrician in Beverly Hills, California, a fellow at the American Academy of Pediatrics (AAP), and a member of the What to Expect Medical Review Board. “It also limits the spread of disease to others.”
There are two MMR vaccines licensed for use in the United States that provide protection against measles, mumps, and rubella. The other vaccine, called MMRV, also protects against chickenpox (varicella). MMRV can be used in children 12 months to 12 years of age.[1]
However, the MMRV vaccine has a slightly higher risk of fever and febrile seizures (those associated with fever) after the first dose than receiving MMR and varicella as two separate vaccines.[2]
When will my baby get the MMR vaccine?
The Centers for Disease Control and Prevention (CDC) recommends two doses of the MMR vaccine. The first is usually given between 12 and 15 months, and the second between 4 and 6 years old (though it can be given any time 28 days or more after the first dose).
Can my baby get the MMR vaccine before age 1?
Not usually, but some babies may be able to get their first dose of the MMR vaccine between the ages of 6 months and 12 months old if they live in an area with active measles outbreaks or if they’ll be traveling to another country, according to the American Academy of Pediatrics (AAP).
If you’re planning to travel internationally, especially to a place where measles is spreading, or if you live in an area where there is an active measles outbreak, talk to your pediatrician. Your child’s doctor will probably recommend giving your baby an initial dose of the MMR vaccine earlier than usual, as long as she’s 6 months old.
Kids who get their first dose before age 1 should still get two more doses according to the regular childhood vaccination schedule. Talk to the doctor if you’re not sure when your child needs her next dose.
If your child is at least 12 months old and not yet fully vaccinated, your doctor will usually suggest that she has the full two doses before you leave for your trip overseas, spaced at least 28 days apart.
What does the MMR vaccine protect against?
The MMR vaccine delivers protection against measles, mumps, and rubella. If it’s an MMRV vaccine (MMR plus varicella), it will also protect against chickenpox.
Measles
Measles is a highly contagious illness that is spread through coughing, sneezing, and even breathing. It can cause a rash all over the body, fever, runny nose, eye irritation, and cough.
Measles can result in an ear infection and also progress to pneumonia, infection of the brain (encephalitis), seizures, permanent brain damage, and even death.
Measles remains a common disease in many parts of the world and is a leading, preventable cause of infant mortality globally. Each year, measles kills almost 140,000 people around the world.[3] The World Health Organization (WHO) estimates that measles vaccination prevented more than 60 million deaths between 2000 and 2023.[4]
While the CDC declared the disease eliminated in the U.S. in 2000 (meaning it was not continuously transmitted for at least 12 months), there have been measles outbreaks in the U.S. more recently, especially among people who have not been vaccinated.
In 2025, a large measles outbreak in rural western Texas had grown to 124 cases across several counties by late February, along with more in New Mexico, mostly among unvaccinated people. One unvaccinated school-age child died after being hospitalized, the first U.S. death from measles since 2015.
Between December 1, 2023 and January 23, 2024, the CDC was notified about 23 confirmed U.S. cases of measles across several states, many among undervaccinated or unvaccinated children and teens. In 2019, there were nearly 1,300 cases of measles confirmed in 31 states, more than any year since 1992.
Travelers can bring measles into the U.S. from countries where the disease still exists, and they can spread measles to people who are unvaccinated or undervaccinated, including those who refuse to be vaccinated, babies who can’t get the vaccine because they’re too young, people who haven’t received all the recommended doses, and those who have specific health conditions.
Mumps
Mumps is spread through saliva or mucus and causes headache, fever, loss of appetite, muscle pain, and inflammation of the salivary glands that leads to swollen cheeks and jaws.
Mumps can cause complications such as meningitis and hearing loss, especially in people who are not vaccinated. Even though the vaccine has drastically reduced mumps cases, outbreaks continue to occur in the U.S.
Rubella
Also known as German measles, rubella is spread through respiratory secretions from an infected person who coughs or sneezes. It causes a fever, rash, swollen tender glands at the back of the neck, and, occasionally, arthritis-like symptoms in the joints.
Sometimes the symptoms are so mild that they’re missed. However, the greatest danger from rubella is to unborn babies who, if their mothers contract rubella during early pregnancy, are at risk of being stillborn or born deaf, blind, mentally impaired, or with brain or heart defects.
That’s why immunization in early childhood is recommended — both to reduce the risk of infected children exposing pregnant women, including their own mothers, and to ensure that female babies will be protected when they reach childbearing age.
“After two doses, the MMR vaccine is 97% effective at preventing measles, 88% effective against mumps, and 97% effective against rubella, so it is highly effective,” says Dr. Crosby. “It is also very safe and provides lifelong protection.”
The MMR vaccine contains weakened measles, mumps, and rubella viruses to protect children from these three diseases. The MMRV vaccine also protects against chickenpox (varicella). it can be used in children between 12 months and 12 years old. The CDC recommends two doses of the MMR vaccine. The first dose is typically given when your child is between 12 and 15 months and the second between 4 and 6 years old. It’s critical to protect your child against these illnesses. For example, measles remains a common disease in parts of the world and is a leading, preventable cause of infant mortality globally. Each year, it kills almost 140,000 people. The odds of your child experiencing side effects from the MMR vaccine are very small. The most common side effects are a sore arm and redness at the injection site.
Does the MMR vaccine have any side effects or risks?
The odds of your child experiencing any side effects from the MMR vaccine are very small.
Typical vaccine reactions such as sore arm or redness at the injection may occur shortly after getting the vaccine and are usually mild. Other reactions such as fever and/or rash may occur seven to 12 days later. The rash will go away on its own and is not contagious or concerning in any way.
“[My baby] was a bit fussy and clingy for a few days,” says What to Expect Community user kp123kp. “She slept a bit more. She had a low-grade fever but it didn’t last more than 12 hours. Overall totally fine!”
Studies have repeatedly and definitively shown that there is absolutely no link between the MMR vaccine and autism or other developmental disorders.
MMR vaccination for adults
Women who are planning to get pregnant need to be up-to-date on their MMR vaccine. Adults who received two doses of the MMR vaccine as children are considered protected for life and usually don’t need a booster dose, though one may be necessary if you’re at risk because of a mumps outbreak.
If you’re unsure whether you were vaccinated or need a booster dose, talk with your health care provider — there’s no harm in getting the MMR vaccine again even if you already got it as a child.
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