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Essential guide to the MMR vaccine

Published: May 12, 2025 | 8 minutes to read

Written by: Max Schochet

A doctor puts an adhesive bandage on a child after vaccination.

Learn about the MMR vaccine and how it helps someone stay protected against measles, mumps and rubella.

Measles is a highly contagious virus, spreading easily when someone coughs or sneezes and lingering in the air for up to two hours. The World Health Organization (WHO) says that “one person infected by measles can infect nine out of ten of their unvaccinated close contacts.”

The MMR (measles, mumps and rubella) vaccine is widely considered by experts as the best way to help protect against measles. But who needs the MMR vaccine? When should children get their first dose? What if someone travels to a place with an active outbreak? And do people need a booster?

This guide provides key information about the MMR vaccine, including how it works, who may need it, when to get it and what health experts recommend for helping stay protected.

In this article:

What is the MMR vaccine?

The MMR vaccine can help protect children, teens and adults from measles, mumps and rubella, three highly contagious viral infections. It's a combination vaccine, meaning it provides protection against multiple diseases.

How the MMR vaccine works

The MMR vaccine is a live vaccine, which means it has a small amount of the weakened forms of the measles, mumps and rubella viruses in it. When someone gets the shot, these weakened viruses make their immune system respond without actually being infected. Their body’s white blood cells recognize the viruses and produce antibodies to fight them. This helps build long-term protection, so if someone is ever exposed in the future, their immune system will know how to fight off the viruses.

What the MMR vaccine helps protect against

  • Measles causes cough, fever, rash and red eyes. It can lead to serious complications, such as encephalitis, pneumonia or even death.
  • Mumps leads to fatigue, fever, jaw pain and swollen cheeks. In some cases, it can cause hearing loss and inflammation of the brain as well as reproductive problems in men.
  • Rubella (German measles) is usually mild with a red rash and fever. But it can be extremely dangerous during pregnancy because it can cause miscarriage or birth defects.

How measles, mumps and rubella spread

  • Measles spreads through the air when an infected person coughs or sneezes or when a person touches an infected surface and then touches their face.
  • Mumps spreads through saliva (like when people share drinks or kiss) or through respiratory droplets when people cough or sneeze.
  • Rubella spreads through coughing and sneezing.

Who needs the MMR vaccine?

The Centers for Disease Control and Protection (CDC) recommends the MMR vaccine for children, teens and adults who are not already immune.

Children

  • First dose at 12 to 15 months old
  • Second dose at 4 to 6 years old

The second dose can be given even earlier as long as it’s at least 28 days after the first dose. Older children who haven't been vaccinated should get one or two doses for protection.

Teens and adults

  • Teens and adults who didn't get both doses of the MMR vaccine as kids might need one or two doses to achieve maximum protection.
  • People born before 1957 are usually considered immune to measles, mumps and rubella. Back then, these diseases were very common, so most people got exposed and developed natural immunity before vaccines were available.
  • People who got their measles vaccine before 1968 might need to be revaccinated because some of the early vaccines didn't work as well.

If someone doesn’t have their vaccination records or a laboratory test showing they’re immune, the CDC suggests getting one or two doses of the MMR vaccine. And don't worry, getting an extra dose is safe, so it's a good idea to get revaccinated if vaccine records are missing or unclear.

Looking to book an MMR vaccine appointment? Schedule an in-person visit with a health care provider or visit a MinuteClinic location today.

Groups at a higher risk of exposure

  • College students — Campuses have close living quarters and frequent social interactions, increasing the risk of outbreaks. Plus, many colleges require proof of immunization. Those unsure of their immunity should get two doses at least 28 days apart. 
  • International travelers — Measles outbreaks are more common in certain countries. Children between 6 and 11 months old should receive one early dose before travel followed by the regular schedule. Teens and adults without proof of immunity should get two doses at least 28 days apart.
  • Health care providers — People working in hospitals or clinics are more likely to be exposed to infectious diseases. If they're not sure they’re already immune, they should get two doses of the vaccine.

Who can’t get the MMR vaccine

Some people are advised not to get the MMR vaccine or to wait:

  • People who are pregnant — Anyone expecting should hold off on getting the MMR vaccine, and those planning for pregnancy should avoid getting pregnant for at least one month after getting the MMR vaccine. It does contain live viruses, which pose a theoretical risk to the baby. 
  • Weakened immune systems — People with weakened immune systems, such as those on chemotherapy or certain medicines, should avoid live vaccines like MMR because the weakened viruses could give them an infection.
  • Severe allergies to the vaccine — Someone with severe, life-threatening allergies to any part of the vaccine is advised to avoid it. Check the ingredients in the MMR vaccine (and any vaccine) before vaccination.
  • Feeling sick — Anyone who has a moderate or severe illness should wait until they recover before getting the vaccine to make sure their immune system responds properly.
  • Blood transfusion or treatments — Anyone who recently had a blood transfusion may need to delay getting the vaccine, because antibodies in the new blood could affect its effectiveness.
  • Active tuberculosis (TB) — Those with active TB, which means the infection is currently making someone sick and their body is fighting it, are usually asked not to get an MMR vaccination.

For an MMR vaccine exemption, contact a health care provider.

Vaccine side effects

Most side effects of the MMR vaccine are mild and go away on their own. In rare cases, more serious reactions can occur.

Common mild side effects

  • Fever
  • Mild rash
  • Sore arm
  • Temporary joint pain and stiffness

Rare but serious side effects

  • Fever-induced seizures
  • Severe allergic reaction (anaphylaxis) 
  • Temporary unusual bleeding or bruising

Anyone experiencing a serious reaction should seek medical attention immediately. For mild side effects, consult a health care provider.

How safe and effective is the vaccine?

The MMR vaccine is safe and effective, though no vaccine guarantees 100 percent immunity. Most people who get the MMR vaccine are protected for life against measles and rubella, according to the CDC; immunity against mumps may decline with time. But even with two doses, some people may still get measles, mumps or rubella if exposed. However, the symptoms are usually milder and they're less likely to spread the diseases.

The latest CDC data shows how well the vaccine works:

One dose:

  • 93% effective against measles
  • 72% effective against mumps
  • 97% effective against rubella

Two doses:

  • 97% effective against measles
  • 86% effective against mumps

Frequently asked questions (FAQ)

Most adults who received the MMR vaccine as children don't need a booster, even if they’ve been exposed to measles, mumps or rubella, according to the CDC. Right now, the CDC says people don't need a third dose of the MMR vaccine during measles outbreaks if they’ve already had the first two doses. In the event of a mumps outbreak, public health authorities may recommend that people at an increased risk for mumps may need to get an additional dose. Check with a health care provider for the best course of action.

Thanks to high vaccination rates, outbreaks of measles, mumps and rubella are less common in the United States. However, these diseases can still pop up. They exist in other countries and travelers can bring them back if they're not vaccinated. This can lead to outbreaks in areas where people haven't gotten their shots or missed a dose.

Consult with a health care provider to determine vaccination status. The CDC also outlines various other methods to determine someone’s status. Additionally, places like MinuteClinic can perform a blood test to check for antibodies against measles, mumps and rubella.

It's generally recommended to get the missed dose as soon as possible, at least four weeks apart. However, contact a health care provider for specific guidance based on personal vaccination history and health status. Learn more about how to schedule a vaccine at a CVS Pharmacy location or MinuteClinic location.

According to the CDC, almost everyone who is exposed to measles, mumps or rubella will become ill if they themselves haven't received the MMR vaccine. Not getting vaccinated can also spread these diseases to others, especially those too young or with medical conditions that prevent vaccination.

Act quickly and contact a health care provider for personalized advice and to determine the best steps based on the situation.

According to the CDC, the MMR vaccine can usually be given at the same time as other vaccines. However, it's recommended to wait at least 28 days after receiving another live vaccine before getting the MMR vaccine. If a second live vaccine is given too early, it might not be as effective at building protection. Check with a health care provider for the best advice.

Yes, the MMR vaccine can be given to breastfeeding people because the baby will not be affected by the vaccine through breast milk. Rubella may transfer through breast milk, but the amount isn’t considered significant.

Most health insurance plans cover the cost of specific vaccines at eligibility when administered by an in-network provider. This may include the MMR vaccine, but it's a good idea to confirm with the insurer.

This content is for informational purposes only and is not medical advice. Consult your health care provider before taking any vitamins or supplements and prior to beginning or changing any health care practices.

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