A confirmed case of measles had been reported in an unvaccinated child under 5 years old, according to the Nassau County Department of Health.

The DOH says this is the first case of measles reported in Nassau County since 2024.

“The Nassau County Department of Health is closely investigating the case, including any potential exposures, and taking the necessary steps to prevent the spread of measles,” said Health Commissioner Dr. Irina Gelman.

Measles can cause serious illness, and if there are complications with other ailments, can result in hospitalization or death.

The DOH says measles is highly contagious and symptoms usually appear 10 to 12 days after exposure.

"The single best way to prevent measles is to be vaccinated," the DOH said, "Individuals should receive two doses of MMR vaccine to be protected."

The Suffolk County Department of Health Services reports zero confirmed cases of measles in the county and says the last reported case was in March 2025.