Health officials said Friday that nearly 700 people at two universities in Los Angeles have been ordered to stay home because they might have had contact this month with two measles patients.

At one point, roughly 1,700 people were under quarantine orders, but by Friday health officials had cleared more than 1,000 who had come forward with proof of vaccination, Los Angeles County public health officials said at a news conference.

The highest number of actively quarantined people, 628, was connected to Cal State Los Angeles, where a single measles patient created hundreds of possible exposures by visiting a campus library, officials said. That number includes at least 106 staff members, according to the university.

"We also issued a blanket order that asked anyone who had been in the library, on 4/11 between 11 and 3 to self-quarantine, notify health services and establish that they were immune before they exposed themselves to the public," said Barbara Ferrer, Los Angeles County's public health director.

Across town at UCLA, 853 students and seven faculty members might have been exposed to one measles patient, she said. Health officials verified immunization for hundreds, leaving 45 students and one faculty member under quarantine Friday, Ferrer said.

The scare is part of a nationwide burst of measles outbreaks in California, New York state, Washington, New Jersey and Michigan, according to the U.S. Centers for Disease Control. In a statement CDC officials blamed "an increase in the number of travelers who get measles abroad and bring it into the U.S., and/or further spread of measles in U.S. communities with pockets of unvaccinated people."

Federal health officials say the number of confirmed measles patients in the United States — 626 in 22 states — is on pace to surpass 2014's record 667 cases. One in 1,000 children who contract the disease will die, according to the CDC.

In Los Angeles County, health officials said international travelers, healthcare workers and those who care for young children should consider a second vaccination. One of the confirmed university cases "did travel internationally prior to coming down with measles," Ferrer said.

There have been five cases of measles in Los Angeles County so far this year, she said.

On Friday, President Donald Trump urged parents to get their children vaccinated.

"This is really going around now, they have to get their shot," he said.

At a 2015 presidential debate, Trump appeared to buy into the claim, discounted by science, that there's a link between childhood vaccination and autism.

"Autism has become an epidemic … I am totally in favor of vaccines," he said at the time. "But I want smaller doses over a longer period of time."

Earlier this year, Michelle Mello, a professor of health research and policy at the Stanford School of Medicine, said in a university Q&A that "one of the most frustrating aspects of this issue for health scholars is the persistence of mistaken beliefs about vaccine risks, which are often traceable to a discredited and retracted study about vaccines and autism.

"As a parent," she continued, "I sleep better knowing my kids are immunized."