Measles

As of March 6, 2025, a total of 222 measles cases have been reported by twelve U.S. jurisdictions this year: Alaska, California, Florida, Georgia, Kentucky, New Jersey, New Mexico, New York City, Pennsylvania, Rhode Island, Texas, and Washington; 201 of which occurred in New Mexico and Texas. Most of the 222 cases are among children who had not received the MMR vaccine.

There have been three outbreaks, with an outbreak defined as three or more related cases, reported in 2025, and 93% of cases are outbreak-associated. For comparison, 16 outbreaks were reported during 2024 and 69% of cases were outbreak-associated.

Measles is a highly contagious viral illness that typically begins with fever, cough, coryza (runny nose), and conjunctivitis (pink eye), lasting 2-4 days prior to rash onset. Measles can cause severe health complications, including pneumonia, encephalitis (inflammation of the brain), and death. The virus is transmitted by direct contact with infectious droplets or by airborne spread when an infected person breathes, coughs, or sneezes. Measles virus can remain infectious in the air and on surfaces for up to 2 hours after an infected person leaves an area.

Infected people are contagious from 4 days before the rash starts through 4 days afterward. The incubation period for measles, from exposure to fever, is usually about 7–10 days, and from exposure to rash onset is usually about 10–14 days (with a range of 7 to 21 days).