Starting at midnight Saturday, travelers on flights from 26 countries in Europe will be channeled through one of 13 U.S. airports, where they will undergo enhanced health screening, be given information about the novel coronavirus and instructed to self-quarantine for 14 days.

The measures will apply to U.S. citizens, green-card holders, their family members and other authorized travelers who have recently traveled from, or otherwise been present, within “a country of the Schengen Area within 14 days of the date of the person’s entry or attempted entry into the United States,” according to a directive issued by acting homeland security secretary Chad Wolf on Friday. Under the new restrictions, most non-U.S. citizens will be blocked from entering the United States from those countries.

The 26 nations of the Schengen Area are Austria, Belgium, the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Italy, Latvia, Liechtenstein, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden and Switzerland.

The flights will be directed to international airports in Boston, Miami, New York City, Chicago, San Francisco, Seattle, Los Angeles, Atlanta, Honolulu, Newark, Dallas, Detroit or Washington, D.C.

The restrictions are part of several new strategies announced this week by the Trump administration, with the goal of slowing the spread of the coronavirus, which has now sickened more than 1,800 people and killed more than 40 in the United States.

Administration officials now think that Europe — not China — is the new hot spot for outbreaks and that reducing the number of people entering the United States from those nations will aid efforts to control the virus’s spread. That belief was reinforced by the World Health Organization on Friday.

Wolf said arriving passengers will be directed to “enhanced entry screening,” where they will be asked about their medical history and current condition, and for contact information to be given to local health authorities. Passengers will then be given written information about the novel coronavirus and instructed to self-quarantine in accordance with Centers for Disease Control and Prevention best practices.

“While the overall risk of serious infection from the coronavirus to the general public remains low at this time, the Trump administration is taking these aggressive measures to keep the risk low, requiring all Americans returning from affected areas in Europe to be funneled through 13 airports for screening upon their return to the U.S.,” Wolf said in a statement.

In an effort to minimize disruption, Wolf said airlines, officers from the Transportation Security Administration and U.S. Customs and Border Protection will work to identify passengers who fit the criteria before they board their previously scheduled flights. Once identified, those passengers would then be put on flights headed to one of the 13 designated airports.

“I understand this new process will be disruptive to some travelers, however this action is needed to protect the general public from further exposure and spread of the coronavirus,” Wolf said. “Once back in the U.S. it is imperative that individuals honor self-quarantine directives to help protect their loved-ones and communities.”

The Trump administration has had similar restrictions in place for travelers from China and Iran.

The new restrictions will require significantly more resources than those already in place, in part because the number of travelers coming from the 26 European nations covered under the new policy dwarfs the number arriving from China and Iran.

Before the restrictions were put into place, roughly 15,000 travelers a day arrived from China, a number that has since dropped to about 1,000. About 66,000 passengers per day typically arrive from the countries subject to Trump’s new order.