As of March 20, 2025, the had reported 378 measles cases across 18 states. Most of these cases are associated with three outbreaks, the largest being in Texas. Of all cases, 75% have been reported among children and young adults up to age 19.
On Tuesday, March 11, the Los Angeles County Department of Public Health reported the county’s first measles case of the year.
Here are some frequently asked questions about measles:
What is measles?
Measles is a very contagious infectious disease spread through coughing, sneezing, talking and breathing. It can remain in the air for up to two hours after an infected person leaves the area, according to the CDC. It’s so contagious that “if one person has it, up to 90% of the people close to that person who are not immune will also become infected,” says the .
People who are fully vaccinated are unlikely to be infected.
Measles can lead to hospitalizations and, in rare cases, death. In 2025, to date, there have been 38 measles-related hospitalizations nationwide, according to the CDC, as well as one confirmed death and one death that is being investigated.
What are the symptoms of measles?
Symptoms typically appear seven to 14 days after exposure. Early symptoms include fever (more than 101 degrees F), cough, runny nose and watery eyes. These are followed by the telltale rash – flat red spots – that follows, starting on the face and spreading to the rest of the body.
How can measles be prevented?
Getting vaccinated is the best way to prevent contracting measles or exposing others to the disease. The measles vaccine, known as the MMR (measles, mumps, rubella) vaccine, has been proven safe and effective.
The recommends children receive their first dose of the MMR vaccine at age 12 to 15 months and a second dose around age 4 to 6. Older children and adults who have no evidence of immunity – or who are unsure if they’ve been vaccinated against the measles – also are advised to get one or two doses of MMR vaccine. Doses should be administered at least 28 days apart, says the CDC.
Those who are not sure if they're up to date on their vaccine should talk to their primary care physician.
How effective are the vaccines?
According to the CDC, one dose is 93% effective in preventing measles; two doses are 97% effective.
Widespread use of measles vaccine, which was introduced in the 1960s, has reduced measles cases by more than 99% compared with the pre-vaccine era, according to the CDC. Protection provided by the vaccine appears to last decades, if not indefinitely.
What should I do if I've been exposed to measles?
You would typically be notified by the Department of Public Health if a measles exposure occurred and you would be given specific instructions dependent on whether you have been vaccinated.
If you've been exposed to measles, immediately call your doctor to let them know. Unless instructed to do so by the Department of Public Health or your physician, do not visit the emergency department. Your doctor will determine if you are immune to measles based on your vaccination record, age or laboratory results and will guide you on next steps.
What should I do if I have measles?
You will be provided instructions by your physician and the Department of Public Health. You should stay home to avoid spreading measles to others. Ask your doctor when it is safe to return to normal activities outside your home.
Other steps you should take:
- Avoid contact with children and people with compromised immune systems, especially those who may not have had their MMR vaccine.
- Make sure to cover your mouth and nose when you cough or sneeze.
- Wash your hands often with soap and water.
- Avoid sharing drinks or utensils.
- Disinfect high-touch surfaces such as toys, doorknobs, tables and counters.
- Call your doctor if you are concerned about symptoms.
