SARS-CoV-2 B.1.617.2 (Delta) Variant COVID-19 Outbreak Associated with a Gymnastics Facility — Oklahoma, April–May 2021

• Published in: MMWR. Morbidity and mortality weekly report 2021-07, Vol.70 (28), p.1004-1007
• Main Authors: Dougherty, Kendra, Mannell, Mike, Naqvi, Ozair, Matson, Dakota, Stone, Jolianne
• Format: Article
• Language: English
• Subjects: Age; Asymptomatic; Contact potentials; Contact tracing; Coronaviruses; COVID-19; COVID-19 vaccines; Disease transmission; Epidemics; Females; Full Report; Gymnastics; Health aspects; Health surveillance; Households; Immunization; Infections; Males; Masks; Medical laboratories; Patients; Public health; Quarantine; Risk analysis; Risk factors; Severe acute respiratory syndrome coronavirus 2; Vaccination; Viral diseases
• ISSN: 0149-2195; 1545-861X
• DOI: 10.15585/mmwr.mm7028e2

During April 15–May 3, 2021, COVID-19 cases occurred in 10 of 16 cohorts, including four of nine male cohorts and six of seven female cohorts, and three staff members. Among cohorts with identified cases, attack rates ranged from 8% to 60% (Table 2) (median = 32% overall; 42% [male]; 20% [female]). Among 26 identified households with cases, five (19%) were lost to follow-up, and no secondary cases were reported from 14 (54%). Among seven households with known secondary transmission, attack rates ranged from 80% to 100%. The overall facility-associated attack rate among 194 exposed persons was 24%, including 26 of 133 (20%) gymnasts and staff members and 42 of 80 (53%) household contacts. Several potential risk factors for transmission were identified through household interviews and direct observations at facility A, including nonadherence to recommended quarantine and testing guidance; delayed recognition of infection because of mild symptoms or attribution of symptoms to other causes; not using masks among active participants, coupled with increased respiration during active sport participation (further, facility A policy was that all persons not actively participating wear masks, but this policy was not always observed); poor facility ventilation; staff members training multiple cohorts; low COVID-19 vaccination coverage among participants (partly related to age eligibility); inadequate cleaning of high-touch surfaces between participant use; and overlapping cohort practice times, facilitating transmission between cohorts. The facility attempted to mitigate transmission by temporarily excluding cohorts with cases and requiring a negative test or 10-day quarantine before return. Other facility A mitigation measures were restricting locker room access, physical distancing in personal belonging storage area, and physical distancing when cohorts moved between practice locations.