San Francisco Bay Area residents may have been exposed to the measles last week after a University of California-Berkeley student with the disease rode on the Bay Area Rapid Transit (BART) trains, Fox News reported.

Health officials said the student, who is in his 20s and lives in Contra Costa County, was not vaccinated and was likely infected with measles during a recent trip abroad to Asia. They warn that there's a possibility that anyone who rode on BART between Feb. 4 and Feb.7 during the morning commute or late evening could have been exposed to the highly contagious respiratory virus, Fox News reported.

The virus can stay in the air for up to two hours.

"Measles is a serious, highly contagious disease," Dr. Janet Berreman, health officer for the city of Berkeley, said in a prepared statement. "It spreads through the air when an infected person coughs or sneezes. Fortunately, the measles vaccine is highly effective in preventing infection."

People who are vaccinated or have had the disease before are unlikely to catch measles.  Anyone who is exposed to it and not immune will probably get the disease, CNN reported.

Measles vaccinations typically are given at an early age and over multiple rounds. A person isn't considered fully vaccinated until they have gone through the whole gamut, meaning that young people midway through that process still may be at risk.

Measles start out much like a common cold, with high fevers, red eyes and a telltale rash often following.

According to the Centers for Disease Control and Prevention, measles can be more serious to certain groups of people, including children. It could cause deafness, ear infections and may even result in death.

University of California-Berkeley will be offering the vaccine to any student on campus who has not been vaccinated against the measles virus, ABC News reported.