Measles is one of the most contagious diseases.

Measles will infect up to 9 out of 10 susceptible people who have close contact to a person with measles. 

Measles is spread in the air when an infected person breathes, coughs, or sneezes. These germs can stay in the air for up to 2 hours after the infected person leaves an area.

What are the symptoms of measles?

Measles causes high fever, tiredness, muscle pain, sore throat, headache, cough, runny nose, red, itchy eyes, and a rash. Sometimes people get Koplik’s spots (red spots with white centers) in the mouth. 

What are the complications of measles?

• Measles can also cause other infections such as pneumonia, ear infections or diarrhea.  
• 1 out of every 1,000 measles cases will develop acute encephalitis (swelling of the brain), which often results in permanent brain damage. 
• 1 to 3 out of every 1,000 children who become infected with measles will die from respiratory and neurologic complications. 
• Measles can cause Subacute Sclerosing Panencephalitis (SSPE) which is a rare, but fatal nervous system infection that happens years after a measles infection.  
• Measles can cause immune amnesia in unvaccinated individuals. This is basically a hard reset of the immune system after being infected with the measles virus. This dangerous process puts people at risk of developing other infections that they would have previously been able to fight because their immune memory cells have been erased. This immune amnesia can last for months to years (2-3 years or longer). Vaccination with the MMR is the best way to prevent measles and the associated immune amnesia.  
• If you are pregnant, in addition to making you sick, measles can cause preterm labor, low birth weight, or miscarriage. 
• Measles can result in death. 

MMR vaccine is the safest way to protect yourself from measles.

Am I protected against measles?

 CDC considers you protected from measles if you have written documentation (records) showing at least one of the following:

• You received two doses of measles-containing vaccine, and you are a(n)—
  • school-aged child (grades K-12)
  • adult who will be in a setting that poses a high risk for measles transmission, including students at post-high school education institutions, healthcare personnel, and international travelers
• You received one dose of measles-containing vaccine, and you are a(n)—
  • preschool-aged child
  • adult who will not be in a high-risk setting for measles transmission
• A laboratory confirmation that you had measles at some point in your life
• A laboratory confirmation that you are immune to measles
• You were born before 1957

What should I do if I’m unsure whether I’m immune to measles?

If you’re unsure whether you’re immune to measles, you should first try to find your vaccination records or documentation of measles immunity. If you do not have written documentation of measles immunity, you should get vaccinated with measles-mumps-rubella (MMR) vaccine. Another option is to have a doctor test your blood to determine whether you’re immune. But this option is likely to cost more and will take two doctor’s visits. There is no harm in getting another dose of MMR vaccine if you may already be immune to measles (or mumps or rubella).

How effective is the measles vaccine?

The measles vaccine is very effective. One dose of measles vaccine is about 93% effective at preventing measles if exposed to the virus. Two doses are about 97% effective.

How safe is the measles vaccine?

The MMR vaccine is a safe vaccine. CDC and the Food and Drug Administration (FDA) are committed to ensuring that vaccines provided to the public are safe and effective. Once vaccines are licensed or authorized for emergency use in the United States, CDC and FDA continuously monitor them through several safety systems. 

Are there side effects to the vaccine?

Common side effects include fever and soreness at the injection site. Some people may experience a mild rash and swollen glands in the neck or cheeks.

As with any medication, there can be adverse effects associated with the MMR vaccine. While very rare, these could include severe allergic reaction following vaccination, increased risk of febrile seizures, temporary low platelet count, and temporary pain or stiffness in joints (mostly in teenage or adult women without prior immunity to rubella).  

Does the MMR Vaccine cause autism?

No. Because signs of autism may appear around the same time children receive the MMR vaccine, some parents may worry that the vaccine causes autism. Vaccine safety experts, including experts at the American Academy of Pediatrics (AAP), agree that MMR vaccine is not responsible for recent increases in the number of children with autism. In 2004, a report by the Institute of Medicine (IOM) concluded that there is no link between autism and MMR vaccine, and that there is no link between autism and vaccines that contain thimerosal as a preservative. There have been many carefully performed scientific studies since then that have found no link between the MMR vaccine and autism. 

Could I still get measles if I am fully vaccinated?

Very few people—about three out of 100—who get two doses of measles vaccine will still get measles if exposed to the virus. Experts aren’t sure why. It could be that their immune systems didn’t respond as well as they should have to the vaccine. But the good news is, fully vaccinated people who get measles are much more likely to have a milder illness. And fully vaccinated people are also less likely to spread the disease to other people, including people who can’t get vaccinated because they are too young or have weakened immune systems.

Do I ever need a booster vaccine for measles?

No. CDC considers people who received two doses of measles vaccine as children according to the U.S. vaccination schedule protected for life, and they do not ever need a booster dose.

Adults need at least one dose of measles vaccine, unless they have evidence of immunity. Adults who are going to be in a setting that poses a high risk for measles transmission should make sure they have had two doses separated by at least 28 days. These adults include students at post-high school education institutions, healthcare personnel, and international travelers.

If you’re not sure whether you were vaccinated, talk with your doctor.