( CNN ) -- Could simply sitting on a train or in a classroom land you in the hospital ? That 's a possibility in Northern California , where health officials are trying to get the word out that a University of California , Berkeley , student may have exposed classmates and strangers to measles . The school 's university health services said a student who contracted measles -- likely during a trip overseas -- had spent time in and around campus and commuting to and from his home in Contra Costa County on Bay Area Rapid Transit , or BART , trains during the February 4 to 7 morning commutes and in the late evening . In the process , he may have infected any number of people , and not just those he rubbed elbows with or shared bodily fluid with . As the Centers for Disease Control and Prevention notes , measles spreads through coughing , sneezing or breathing and `` any child who is exposed to it and is not immune will probably get the disease . '' Erika Jenssen , the communicable disease program director for Contra Costa Health Services , said Thursday even those who shared the same airspace as the infected student 1 to 2 hours after the fact -- and who have not been vaccinated for measles -- may get sick . `` Measles is a very serious viral illness , '' Jenssen told reporters , `` and it is very contagious . '' The good news is that the majority of Americans ca n't get it , because they are vaccinated for life . The Berkeley student , though , was not vaccinated . Measles start out much like a common cold , with high fevers , red eyes and a telltale rash often following . Children are particularly susceptible : About 10 % of them who get measles come down with ear infections , and roughly 5 % end up with pneumonia . One or two of 1,000 children with measles die , according to the CDC . Measles vaccinations typically are given at an early age and over multiple rounds . A person is n'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 .
A UC Berkeley student diagnosed with the measles may have exposed himself . Health officials issue warning to students , those who commuted on time . ` ` Measles is a very serious viral illness , and it is very contagious , '' he says .