Chicago Public Schools officials are asking students and employees of a high school closed after an aide tested positive for the novel coronavirus to self quarantine through March 18 — but they are placing no restrictions on students’ siblings or others who might have come into contact with members of the school community.

The district announced Friday that an aide at Vaughn Occupational School, which serves about 200 students with complex special needs, had tested positive for the coronavirus. The Northwest Side school will close starting Monday, but officials stressed again Saturday the case at Vaughn remains “an isolated incident.”

In an email to district families and staff, CEO Janice Jackson and Chicago Public Health Commissioner Allison Arwady said public health officials consider the immediate risk to the general public to be low.

“While we understand that this is a concerning development, it is critically important that our community share only trusted sources of information and not spread misinformation,” the email said.

The aide, a woman in her 50s, had vacationed on the Grand Princess cruise ship and disembarked Feb. 21. She went to work at Vaughn on Feb. 25 and last worked there on Wednesday. The sixth confirmed coronavirus case in Cook County, she is now hospitalized.

Vaughn doesn’t have attendance boundaries, drawing students from different parts of the city, so siblings could attend a number of schools.

The district is asking anyone who has visited Vaughn since Feb. 25 to stay home through March 18 unless seeking medical care. People who have not been at the school during that time face no district restrictions, even if they have come into contact with someone at Vaughn. They can go to school or work in the district as long as they don’t feel sick. That includes family members of Vaughn students and employees and students who shared a bus with Vaughn students.

Chicago Department of Public Health staff are contacting all Vaughn students, educators, and staff this weekend. Officials said that any students or employees who develop symptoms will have access to a novel coronavirus test as early as this weekend. Officials said the district has begun a thorough cleaning of the Vaughn school building and removed buses that served the school for additional cleaning.

The number of schools in the U.S. that have closed because of the virus is growing.  A school district north of Seattle closed all of its schools Thursday, and private schools in New York and Denver have also closed in attempts to curb the spread. The University of Washington and Stanford University have cancelled in-person classes.