BOSTON (AP) — Massachusetts officials are launching an aggressive plan to regularly disinfect the state transit system and are calling on colleges and high schools to cancel study abroad programs as more than 700 residents have been quarantined amid the global spread of the novel coronavirus.

Gov. Charlie Baker and other state officials also said Wednesday that all residents returning from China, Italy, Iran, and South Korea will be required to self-quarantine as part of new travel directives from the federal government.

Baker and others stressed the stepped-up measures are precautionary and that the risk of contracting the virus in Massachusetts remains low.

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The state has one confirmed case and one presumptive positive case of the virus, which causes the disease COVID-19.

More than 400 of the 719 people self-quarantined have already completed the mandatory, two-week monitoring and were cleared to leave their homes, according to state Secretary of Health and Human Services Marylou Sudders.

Roughly 250 remain in the protocol, which includes taking their temperature daily and updating local health officials if they develop a fever, cough or other symptoms, she said.

Twenty people have also been tested for the virus, with most of the results coming back negative and a “handful” of results still pending, Sudders said.

The state’s transit system, meanwhile, plans to disinfect all subway and commuter trains, buses and other public vehicles daily.

Guard rails, handrails and fare equipment will also be cleaned every four hours, and hand sanitizing stations will be installed at subway stations and other transit facilities, said Steve Poftak, general manager of the Massachusetts Bay Transportation Authority.

The state university system and other colleges in the state have already recalled students from China, South Korea, Iran, and Italy, according to Kumble Subbaswamy, the chancellor of the University of Massachusetts, Amherst.

Many are also planning to keep dormitories and dining halls open during spring break for students concerned about travelling.

Baker said officials are also weighing whether to cancel or alter major public events in the state, including Boston’s St. Patrick’s Day Parade and the Boston Marathon.

Seafood Expo North America, the largest seafood expo in North America, announced Tuesday it was postponing the event, which had been slated for later this month in Boston.