Survey and results
University A student-athletes returned to campus* in June and were required to take two negative real-time SARS-CoV-2 reverse transcription-polymerase chain reaction (RT-PCR) tests before participating in pre-season training activities. Voluntary training sessions for both football teams began in July. In August, a member of the men’s soccer team reported COVID-19-related symptoms to coaches (Figure). The student reported attending several social gatherings with teammates over the previous 14 days, including a birthday party and an unsanctioned soccer game between the men’s and women’s teams. Over the next two days, five more footballers reported symptoms and both teams were instructed to isolate or quarantine.† Specimens were collected from symptomatic soccer players and anyone else attending the birthday party or mixed soccer match. Nine out of 10 tests returned positive results for SARS-CoV-2. Three days later, four more footballers received positive results. After the university required both teams to test all members, including asymptomatic individuals, four additional players infected with SARS-CoV-2 were identified, for a total of 17.
All samples tested for SARS-CoV-2 within its jurisdiction must be reported to CDPH, as must all COVID-19 clusters or outbreaks in congregate settings, including universities.§ A case-control study was conducted to evaluate the exposure of football players from the two teams who participated in training sessions, from the day the voluntary training sessions began (day 0) until the day the two teams were ordered to quarantine (day 18) (the investigation period). .¶ A questionnaire was administered to collect symptom history, housing information, training details, contacts, and information on participation in social gatherings, use of masks, and social distancing behaviors. Self-reported SARS-CoV-2 test results were confirmed using the university’s electronic medical records system and the Illinois National Electronic Disease Surveillance System (I-NEDSS). A patient (a student with COVID-19) was defined as a person on the men’s or women’s soccer team with a positive SARS-CoV-2 RT-PCR test result who participated in training sessions during the investigation period. The controls included students from either football team who participated in training sessions during the investigation period and received a negative SARS-CoV-RT-PCR test result. 2 during days 0 to 30. Logistic regression estimated odds ratios (ORs) and 95% confidence intervals (CIs) to determine the association between reported accommodations, participation in social gatherings, and participation in mixed matches with a positive SARS-CoV-2 test result. Analyzes were carried out with SAS software (version 9.4; SAS Institute). Whole genome sequencing was performed on the available samples to identify phylogenetic relationships based on nucleotide differences. This activity was reviewed by the CDC and was conducted in accordance with applicable federal law and CDC policy.**
All students who participated in the training sessions during the investigation period (n = 45) were interviewed, among whom 17 cases of SARS-CoV-2 were identified (attack rate = 37.8%); the other 28 students served as controls. The 45 students consisted of 21 (46.7%) players from the men’s team, 23 (51.1%) from the women’s team, and one staff member from the women’s team (Painting). Median age was 20 years (interquartile range (IQR) = 18-21 years), 46.7% were non-Hispanic White, and 33.3% were Hispanic or Latino. Thirty-three (73.3%) students lived in shared housing with other teammates. In addition to the co-ed soccer game, 18 social gatherings were reported during the survey period, including a birthday party, visits to friends’ dorms or apartments, and outdoor gatherings at the waterfront. a lake. Most students (60.0%) reported attending at least one gathering. Additionally, seven students who reported not attending any social gatherings were listed as contacts at the event by other teammates. All 17 students with COVID-19 attended at least one gathering. Among students with COVID-19, the median number of days between last negative SARS-CoV-2 RT-PCR test and first positive test result was 25.0 days (IQR = 22.0-26.5 days). Eleven of the students with COVID-19 reported symptoms. None of the students were hospitalized. Compared to controls, students with COVID-19 were more likely to live in shared housing with teammates (OR = 10.4; 95% CI = 1.2 to 89.6).
Likely exposure periods and trigger windows (the period when a student with COVID-19 was likely contagious and was not isolated)†† were determined for each student with COVID-19 based on laboratory data and symptom history (Supplementary Figure, https://stacks.cdc.gov/view/cdc/95822). Of the 12 events (events 2 to 13) that occurred during the students’ likely exposure periods, seven (events 3, 5, and 9 to 13) occurred 2 to 5 days before the onset of symptoms or positive test results. SARS-CoV-2 test. The members of the two teams mostly attended different events; however, three events (event 3 (a birthday party), event 5 (a visit to a dorm or apartment), and event 11 (a co-ed soccer game)) most likely contributed to the transmission because they brought together members of both teams and people not involved. on the teams. The birthday party was attended by seven members of the men’s team (M1-M7), who reported wearing masks or social distancing <10% of the time and all of whom subsequently received positive SARS test results -CoV-2. The teammates knew two student-athletes who were not on the football teams and who were also diagnosed with COVID-19 after the event; investigators confirmed a positive SARS-CoV-2 test result using the I-NEDSS. A visit to a dormitory or apartment (event 5) was attended by students M2 to M7 and a player from the women's team (W6), who subsequently had a positive SARS-CoV-2 test result. Seven days later, these same students attended the mixed football match (event 11) with 21 teammates; five additional students subsequently received a positive SARS-CoV-2 test result. Several other events occurred before the co-ed soccer game, including four lakeside gatherings (Events 2 and 8–10), which also overlapped with the student exposure periods and elicitation windows.
Twelve specimens collected from 10 students during days 23 to 33§§ were sequenced and found to be genetically similar, consistent with a single source of introduction of SARS-CoV-2, although the exact chain of transmission could not be determined. Sequences in this group belong to the same clade¶¶ known to be circulating in the Chicago area since March and linked to viral sequences originating in New York.***
