An overnight retreat in Wisconsin this summer involving 152 high school-aged boys, counselors and staff resulted in 116 coronavirus infections after one student who had tested negative for the virus a week prior to the trip began exhibiting symptoms shortly after arrival.
According to a Centers for Disease Control and Prevention (CDC) case report, the trip, which was a faith-based education retreat for boys in grades 9-11, required all attendees to provide documentation of either a positive antibody test within the past three months, or a negative coronavirus test within a week before travel. The attendees were required to self-quarantine within their households for the week prior to travel, and instructed to wear masks during travel.
On July 2, the students traveled to a regional hub and met with counselors and staff members before boarding three buses to travel to the retreat.
Once the student attendees arrived at the retreat, they did not have to wear masks or social distance and were allowed to mix freely. Classes were held outside, and the teachers wore masks and social distanced from students. The 127 students slept in dorms and yurts with counselors rooming together and four staff members housed separately.
On July 3, one of the ninth grade students who had tested negative for coronavirus less than week prior to the trip began experiencing sore throat, cough and chills. On July 5, the student tested positive for the novel coronavirus, according to the report.
The student was isolated in a private room, and 11 of his close contacts were quarantined together in a separate dorm. The 11 contacts were released from quarantine on July 7 after receiving negative rapid SARS-CoV-2 antigen results, “but neither the tests that were conducted nor the results could be verified by public health,” the CDC reported.
Six of those 11 contacts and 18 additional students reported new onset of mild symptoms between July 4-7, and they were given masks but were not isolated. On July 13, a second student tested positive for the virus at a local clinic. On July 15, the Wisconsin Department of Health was notified and began investigating the outbreak, which included multiple testing periods.
“Among 152 attendees, 116 were classified as having confirmed or probable COVID-19,” the CDC reported.
At least one confirmed case occurred in every dorm room and yurt, according to the report. Of the attendees, 24 had provided a positive antibody test prior to traveling to the retreat. All 24 of those attendees tested negative for the virus, but six reported experiencing mild symptoms at the retreat. Those six, however, were not classified as having confirmed or probable COVID-19.
“SARS-CoV-2 can spread rapidly among adolescents and young adults in a congregant setting with inadequate COVID-19 mitigation measures,” the CDC report said. “These findings provide preliminary evidence that detectable antibodies might provide protection against new SARS-CoV-2 infections for an unknown duration. A robust COVID-19 mitigation plan developed in collaboration with public health authorities is important for preventing and containing similar outbreaks at overnight camps and residential schools.”