St. Louis County Executive Sam Page said the woman was studying abroad in Italy and recently returned to St. Louis. Here's how the situation developed:
Monday, March 2:
The 20-year-old woman flew in from Italy and landed at Chicago O'Hare International Airport. She stayed two days with friends in Chicago.
Wednesday, March 4:
The woman took an Amtrak Train 303 to the St. Louis downtown station at the Gateway Transportation Center. According to Amtrak's Train Status tracker, the 303 train left the Chicago station around 9:25 a.m. and arrived in St. Louis around 2:30 p.m.
Amtrak released a statement on Sunday saying the train that the patient boarded has been taken out of service as a precaution. The train along with the St. Louis and Chicago stations will be cleaned and disinfected.
"We are working in close contact with public health and emergency management teams to have the best available information to be able to share with our customers and employees who might be affected. Amtrak is notifying passengers and employees who may have been on the same train," the statement read.
Thursday, March 5:
Page said the woman called the county's health hotline and told them she had a fever and breathing issues. Health officials then asked her and her family to self-quarantine. Page said county officials stayed in touch with the family.
Friday, March 6:
Mercy Hospital St. Louis staff prepared for the patient's visit and tested her. She was released from the hospital as her symptoms were not too severe to keep her admitted.
Saturday, March 7:
Doctor Randall Williams, the director of the Missouri Department of Health and Senior Services, said he received a phone call about the woman's positive coronavirus diagnosis at 1 p.m. Saturday.
The infected woman's father and younger daughter attended an event at the home of a John Burroughs School family member, according to the school. Shortly after, they both went to a father-daughter dinner dance for the Villa Duchesne and Oak Hill School at the Ritz-Carlton in Clayton. The dance was scheduled to begin at 6:30 p.m. The patient's sister is a freshman at Villa.
Page said the family was informed about the positive diagnosis between 6 and 6:30 p.m. He said it takes several hours to prepare for a formal interview with patients as there are certain bylaws and guidelines to follow.
At 7:15 p.m., Page, along with Missouri Governor Mike Parson, made a public announcement about the first confirmed coronavirus case in St. Louis County and the state.
Sunday, March 8:
Page and other health officials were informed about the patient's family members attending the school dance. In an early Sunday evening press conference, Page said health officials contacted the father and told him "to stay home or they will issue a formal quarantine that will require him and the rest of his family to stay home by the force of law."
County officials are retracing the family's steps and are trying to identify all people who may have been in contact with them. Page said the county is using all their resources on this.
John Burroughs School, Chaminade College Preparatory School, the Mary Institute and St. Louis Country Day School and the Archdiocese of St. Louis released statements saying students who have family members who went to the dance should stay home and self-quarantine.
After learning about the confirmed COVID-19 case, Amtrak took the train the woman boarded out of service as a precaution.