The state is experiencing a big increase in measles cases.
ABC7 News spoke with some people in Berkeley who don't want to vaccinate their children.
Dora Lopez Bonneau got an email from a friend Monday warning her a second student at UC Berkeley has been infected with measles.
"It's concerning for sure, you know people have varying degrees of health," Bonneau said.
Unlike the first student who took several trips on BART, the latest rode just once. Cal had a clinic this weekend for those on campus who may have been exposed.
There are now 51 measles cases reported statewide so far this year, including 11 in the Bay Area. That's a huge jump from four cases in California this time last year.
Carolyn: "Why haven't you been vaccinated? "
"I don't know. It's one shot, I guess I didn't feel like taking," UC Berkeley student Julian Lake said.
For most of us measles is a mild disease with a high fever and rash, for others it can be serious.
"It can result in hospitalization and inflammation of the brain and spinal fluid," Berkeley health department spokesperson Janet Berreman said.
Measles had all but disappeared in the United States. Some fear it could be making a comeback because of a growing anti-vaccine movement.
One of the best known activists is actress and host of The View, Jenny Mccarthy, who believes vaccines are linked to autism.
Don Grundmann of Vaccination Liberation also sees them as harmful.
"And so we can have an idealistic view of vaccines of how good they are, but when you get down where the rubber meets the road and when you actually analyze what's in, can we really say with 100 percent certainty that, that does not harm the human body? We say no," Grundmann said.
The head of Berkeley's public health department is a pediatrician.
"Had the opportunity to see first-hand the effect of both vaccinations in protecting children and the effect of non-vaccinations in terms of illness in the population," Berreman said.
Measles is highly contagious. The student diagnosed at UC Berkeley on Friday will remain in isolation until Tuesday.