Two New York City teachers are under self-quarantine because of the threat of coronavirus after they returned with a group of 44 students from Italy on a trip they took for winter break in February.

One of the teachers with James Madison High School experienced possible symptoms of the virus but her tests came back negative, Mayor Bill de Blasio said at a press conference Thursday.

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In total, six adults attended the trip abroad to northern Italy, where 148 people have died from coronavirus and over 3,000 cases have been detected. Two other teachers have been tested as well but their results are not yet known. No students have experienced symptoms and it is unclear if they will undergo testing.

“Right now, the most important thing is that the teacher is not in contact with students and won’t be in contact with students until it’s safe to be,” de Blasio said.

Disease detectives are working to determine the close contacts of others at the Brooklyn school but Schools Chancellor Richard Carranza said he believes the risk to the community is low.

“CDC-approved cleaning supplies have been provided in all 1,800 schools. Deep cleaning will be required two times a week,” de Blasio said.

Carranza added that closing schools in the city is a "last option."

He added that if a student seems to be ill, teachers and school officials should ask them to wear a mask "only for protective purposes."

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"We will call a parent or a guardian to come and pick up the student and then the instruction is for the parent or guardian to get medical care,” Carranza said.

De Blasio also said the Department of Health is asking New Yorkers who return from countries with high numbers of coronavirus cases to self-isolate for 14 days as a precaution. The states include China, Iran, Italy, South Korea and Japan.

State officials say there are at least 22 cases of the virus in New York and the city health department is monitoring 2,773 New Yorkers for home isolation.