The city’s education department is taking an inventory of school trips as concern about the spread of the coronavirus grows, officials announced Thursday.

The global spread of the virus coincided with a week-long school vacation, Feb. 17-21, during which some students and school employees traveled out of the country. Tracking down those who were abroad could take some time, given the school system’s size.

Mayor Bill de Blasio said one teacher had tested negative for the virus after traveling to Italy as part of a school trip with James Madison High School in Brooklyn. More than 40 students took part in the trip, along with six other school staffers. None of the students from Madison have shown symptoms, the mayor said, and therefore have not been asked to stay home.

Two other teachers who traveled to Italy on vacation are awaiting the results of testing and are not currently in school. One educator returned to her classroom for several days after a trip before showing any symptoms. The mayor said the city would follow up with those schools if needed once the results are known.

It’s unclear how many school-organized trips to affected countries — which include China, South Korea, Japan, Italy, and Iran — have taken place since the coronavirus outbreak. But James Madison is not alone. Brooklyn’s Edward R. Murrow High School also organized a trip to Italy during the February break, according to students and staff there, some of whom shared concerns that those on the trip were not asked to stay home.

“These kids came back and came into the general population,” said one Murrow staffer who spoke on condition of anonymity because they were not authorized to speak publicly.

“It seemed foolhardy,” the staffer added.

Symptoms of the coronavirus include fever, coughing, and shortness of breath.

Guidance from the Centers for Disease Control and Prevention for travelers returning to the U.S. has shifted since the students returned. The most recent guidance advises people returning from Italy to stay home for 14 days. Though the Murrow and Madison students returned fewer than 14 days ago, they are not being asked to stay home.

“The health and safety of our students comes first, and we believe the guidance issued to students was consistent with federal guidelines at the time,” education department spokesperson Miranda Barbot wrote in an email.

Despite the more recent federal guidelines that call on people to stay home, city officials said they were not recommending students on those trips self-quarantine because they believe the risk is relatively low. “At this point, it wouldn’t be a time to start a quarantine, unless we saw something problematic,” de Blasio said.

“No need for it,” added Oxiris Barbot, commissioner of the New York City Department of Health and Mental Hygiene.

Schools Chancellor Richard Carranza said that the city now has protocols in place to track future school trips, but the city is still trying to reconstruct where students and teachers may have previously traveled. The scope of the department’s effort to track school trips — in terms of timeframe and locations — was not immediately clear.

Pressed on why the city doesn’t already have that information, the chancellor noted the size of the system, which includes over a million students and roughly 75,000 teachers. Some trips may not have been directly sponsored by the school, but by parent organizations, Carranza said.

De Blasio added: “The bottom line is, we’re going to inventory everything now, and go back and look if there’s anything we need to follow up on,” he said. “We’re going to inventory everything and we’re going to be very transparent about it.”

The chancellor added that the school system is sharing guidance and providing cleaning supplies to private schools.

“We are here to serve the children of New York City — all children,” Carranza said.

In the meantime, some students at Murrow High School said classes and school activities were going on as usual.

Others expressed concern about students returning from Italy, which has locked down certain towns and closed schools and universities across the country. “It’s a little scary, a little nerve-wracking,” said sophomore Shawn Robinson.

Barbot said no one at Murrow is being tested because no one is symptomatic and that the education department is in contact with school officials, who did not reply to Chalkbeat’s requests for comment.

The city’s health commissioner also released a new order on Thursday for city employees, including teachers. The guidance allows the city to require employees to be tested for the virus, or require a quarantine for those who may refuse testing — or “face employment consequences,” de Blasio said.