A Chicago public high school serving about 200 students with complex special needs will be shut down starting Monday after a school aide tested positive for the novel coronavirus, city officials announced Friday evening.

The aide, who is in her 50s, had vacationed on the Grand Princess cruise ship and disembarked Feb. 21. She reported to work at Vaughn Occupational High School on the city’s northwest side on Feb. 25. She last worked at Vaughn on Wednesday, March 4, and is currently hospitalized, officials said. It is the sixth confirmed coronavirus case in Cook County.

Now the ship, returning from a subsequent cruise to Hawaii, has been ordered to remain offshore of San Francisco. Twenty-one crew members and passengers, confined on board, have tested positive for the novel coronavirus.

“I want to reassure all of our CPS students and families that our city has been working relentlessly to protect the safety and security of our students, facility, and staff — along with their friends and loved ones,” Chicago Mayor Lori Lightfoot said at a news conference. She said city officials have already launched an “extensive comprehensive outreach effort to connect with CPS family, staff, and personnel and will continue to do so.”

In robocalls and e-mails to Chicago Public Schools families Friday night, the district said it did not plan to shutter additional schools at this time and was basing that decision on recommendations from local health authorities. The notices described heightened measures around when staff can return to schools after travel. School staff must wait 14 days to return to school if they travel to any location with a “Level 2 or 3” health travel notice, including airport layovers.

The district also said Friday that sick employees will receive paid leave, even if they are out of sick time, and that its facilities department had “pre-ordered” additional hand washing soap, disinfecting solution, and surface wipes to send to schools. Leaders said earlier in the week that additional cleaning supplies and hand soap were being sent to schools.

The cruise ship the aide had vacationed on has been docked outside of San Francisco since Wednesday, after a passenger who was aboard a previous cruise on the same ship reportedly was confirmed positive for the virus and later died.

In a statement Friday, Chicago Teachers Union spokesperson Ronnie Reese urged educators, administrators, staff, and students in all CPS school communities to continue to stay informed and take precautions around cleanliness.

“We also call on the district to rapidly ramp up its efforts to clean and disinfect all schools throughout the city to prevent the spread of the virus,” he said.

“CPS has assured us that Vaughn faculty and staff will not face any financial hardship, and will be compensated during the quarantine,” the union statement said. “Parents and guardians affected by this outbreak may need to provide around-the-clock personal care for their children, so we urge Mayor Lori Lightfoot and Gov. J.B. Pritzker to ensure they can do so without employment risk or household hardship. No one should lose their job due to this crisis.”

So far only a few schools in the U.S. have closed because of the outbreak — but that number is likely to grow. On Wednesday, Los Angeles declared a public health emergency and has urged the community to prepare for the possibility of school closures in the country’s second largest school district, NPR reported.  Northshore School District, north of Seattle, closed all of its schools beginning Thursday, for up to 14 days. The district has nearly 24,000 students.

The virus also has shut down private schools. On Monday, SAR Academy in the Riverdale section of the Bronx closed after a student’s father was confirmed to be the second person in New York to have coronavirus.  In Colorado, St. Anne’s Episcopal School, a private school in Denver, closed Friday as a precaution after the parent of a student tested positive for COVID-19.

And public health officials said a student in Douglas County southeast of Denver tested positive after returning from a trip to the Philippines. Public health officials do not believe the student attended school since returning from abroad. A school district official said the student was not on a school trip.

Correction: This story has been updated to reflect that the aide’s last day at Vaughn was on Wednesday, March 4, not Monday, March 2.