August 2025

Measles is a highly contagious — and sometimes dangerous — viral infection. Roughly 90% of people who are exposed to the measles virus will contract measles — unless they are vaccinated.

Why is measles dangerous?

While often viewed as a mild childhood illness, measles can have serious consequences. Roughly 20% of unvaccinated Americans who get measles are hospitalized, according to the CDC. About 5% of children who get measles will get pneumonia, and one out of 1,000 will develop encephalitis (a serious swelling of the brain). Sadly, one to three out of every 1,000 kids who get measles will die from complications.

Who is most at risk from measles?

Serious complications can affect anyone, but those at higher risk include:

• Kids under five years old
• Adults over 20 years old
• Pregnant women

People with weakened immune systems, such as those with transplanted organs, HIV, or leukemia.

How can you prevent measles?

Measles is preventable through vaccination. Two doses of the MMR vaccine (which protects against measles, mumps, and rubella) or the MMRV vaccine (which also protects against varicella, aka chicken pox) are enough to protect most people from measles for life.

When should children get the measles vaccine?

Children should get their first dose of either the MMR or MMRV vaccine between the ages of 12 and 15 months, and they should get their second dose between four and six years old. But it’s never too late for children and adults to receive the vaccine. Doses for older children and adults need to be at least 28 days apart. Ask your doctor for guidance.