A measles outbreak that began at Disneyland has ballooned to 78 cases, prompting public health officials to urge those who are not vaccinated to avoid the amusement park and other places where large numbers congregate, such as airports and malls.

Of the 78 cases announced Friday, 58 have been linked to a December exposure at Disney parks in Southern California, according to the California Department of Public Health. At least five are Disney employees.

“It is safe to visit these places, including the Disneyland Resort, if you are vaccinated,” said Dr. Gil Chavez, state epidemiologist and deputy director of the Center for Infectious Diseases at the California Department of Public Health. “Therefore, CDPH recommends that anyone not already immunized against measles gets immunized at this time.”

Unvaccinated Disneyland employees, or those who can’t confirm they have been vaccinated, are being asked to go on paid leave, Disney officials said, according to The Los Angeles Times.

The measles outbreak has shined a spotlight on parents who refuse to vaccinate their children. Some are convinced the vaccine can cause autism, despite scientific support of the contrary. Health officials have said, though, they believe an international traveler brought the highly contagious respiratory disease to Disneyland or Disney California Adventure, according to The Associated Press.

Although measles was eliminated in the United States—meaning there were no cases for more than 12 months— in 2000, large international outbreaks still occur, according to the Centers for Disease Control and Prevention.

The majority of those infected so far, 68, live in California. The remainder reside in Utah, Mexico, Arizona, Washington, Colorado, Oregon, and Nebraska, according to the California Department of Public Health.

At least 28 of the Californians who contracted measles were not vaccinated. It’s recommended that the first dose for the vaccine, MMR, be given to children aged 12 to 15 months, which means babies rely on others to get vaccinated to protect them from the disease. The second dose is usually given before kindergarten. Two doses are more than 99% effective, public health officials said.

At least four of the California patients are too young to be vaccinated, while 61% were more than 20 years old, 18% were between the ages of 5 and 19 and 21% were under 4.

Some local school district officials in California have urged unvaccinated students to stay home. Meanwhile, hospitals are urging those who think they may have the virus to call ahead so healthcare workers can properly prepare. Hundreds of people at two hospitals in Oakland, California and Colorado Springs, Colorado were exposed to the disease when infected patients came for help, USA Today reported.

Measles symptoms include fever, cough, runny nose, conjunctivitis and rash.

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