MORE THAN 1,000 students and staff members at two Los Angeles universities were quarantined on campus or sent home this week in one of the most sweeping efforts yet by public health authorities to contain the spread of measles in the US.

By Friday afternoon, two days after Los Angeles County ordered the precautions, about 325 of those affected had been cleared to return after proving their immunity to the disease, through either medical records or tests, health officials said.

The action at the University of University of California, Los Angeles, and California State University, Los Angeles — which together have more than 65,000 students — reflected the seriousness with which public health officials are taking the nation’s outbreak.

“Measles actually kills people, so we have to take that really seriously,” said Dr Armand Dorian, chief medical officer at USC Verdugo Hills Hospital.

Those under the quarantine were instructed to stay at home and avoid contact with others. They also were barred from travelling by public transportation, including planes, trains, buses or taxis. If they must travel for an emergency, they were told to notify public health officials first.

“This is a legally binding order,” the county’s public health director, Dr Barbara Ferrer, told reporters.

Anyone who violates it could be prosecuted, she said, but added that it appears everyone is cooperating so far. She didn’t describe what penalties those who don’t could face.

The number of measles cases in the US has climbed to nearly 700 this year, including five in Los Angeles County and 38 altogether in California. The surge is blamed largely on parents not getting their children vaccinated because of misinformation about the supposed dangers.

Yesterday, Donald Trump urged everyone to get vaccinated.

Authorities ordered mandatory vaccinations earlier their month in the affected Brooklyn neighborhoods and threatened fines of $1,000. City officials said earlier this week that 12 people had been issued summonses.