Measles is a very contagious illness that has recently resurged in the U.S. and worldwide. Measles was declared eliminated in the U.S. in 2000, but recent outbreaks threaten that elimination status. Measles can result in serious illness, especially in young children and people with a compromised immune system. Fortunately, the vaccine to prevent measles (MMR) is highly effective and can prevent almost all cases of illness.
Learn about the current measles case counts and outbreaks from the CDC.
Measles is caused by the highly contagious measles virus. Measles virus infects the respiratory system and then spreads throughout the body, causing more widespread symptoms and, in severe cases, complications.
Symptoms of measles appear 1-2 weeks following exposure. Initial symptoms include a high fever, cough, runny nose, and red, watery eyes. After 2-3 days, white spots may appear inside the mouth. After 3-5 days, a rash typically appears, beginning at the hairline and spreading downward to the neck, trunk, arms, legs, and feet.
Measles is very contagious. It is spread through coughing and sneezing. If a person breathes the air in a room up to 2 hours after a person with measles spent time there, they can contract measles. An infected person is contagious up to 4 days before their rash appears and for 4 days following the start of their rash.
There are no medications to directly treat measles. Comfort measures to relieve symptoms include rest, hydration, fever reducers may be helpful. If an unvaccinated person has been exposed to measles, they can get vaccinated within 72 hours to prevent illness. Exposed individuals who are not eligible for vaccine can receive measles immune globulin to prevent illness.
The U.S. reported fewer than 100 cases of measles each year between 2000 and 2010 due to international travel. However, large outbreaks occurred in 2014, 2019, and 2025 involving community spread. These outbreaks occurred in communities where children did not receive the MMR vaccine to prevent spread, or only received one vaccine dose. At least 95% of the community must be vaccinated to prevent spread.
Check vaccination rates at your school using the CDPHE Immunization Data.
Measles can cause serious illness, especially for infants and children younger than 5. Pregnant women and people with a weakened immune system can also have severe complications, including pneumonia and encephalitis (swelling of the brain). About 1 in 5 unvaccinated people who have measles in the U.S. require hospitalization. If you or a family member has contact with a person with measles or may have measles, isolate and contact your healthcare provider immediately.
The best way to prevent measles is to get vaccinated. The MMR vaccine provides protection against three viruses: measles, mumps, and rubella. The measles vaccine is very effective. Two doses of measles vaccine are about 97% effective at preventing measles if exposed to the virus. Children should get a dose of MMR vaccine at age 12-15 months and again at ages 4-6. Infants traveling internationally should get an early dose of MMR between ages 6 and 11 months.