The Rockland County Department of Health warned residents on Friday of a potential exposure to measles in Spring Valley.

Health officials say the possible exposure happened on Saturday Nov. 29, between 10 a.m. and 3 p.m., at the Food Fair Wholesale Fresh Market at 175 East Central Ave.

The department urges high-risk residents who may have been at that location during that time to immediately contact their health care provider by phone prior to going for medical care.

Those who are at high risk are pregnant women, children under 6 months of age, the immunocompromised or immunosuppressed or those who have not been vaccinated against the measles.

Health officials say measles is one of the most contagious viruses, with 90% of unvaccinated people exposed to the virus becoming infected. People can catch measles just by being in a room where a person infected with the disease has been, for up to 2 hours after the infected person has left and prior to that person even having measles rashes.

Symptoms usually appear 10 to 12 days after exposure but may appear as early as seven days and as late as 21 days after exposure.

Health officials say severe illness like pneumonia, encephalitis, hospitalization and death can occur in those who have not been vaccinated.

Officials say the county will offer free vaccines for measles, mumps, and rubella (MMR) through the Rockland County Department of Health Vaccination Van on Monday Dec. 8 from 10 a.m. to 3 p.m. at Food Fair Wholesale Fresh Market parking lot.