A ninth-grade boy was likely the source of a coronavirus outbreak that sickened nearly three-quarters of the students and staff at a faith-based overnight summer school retreat in southeastern Wisconsin, according to a report released Thursday by the Centers for Disease Control and Prevention.
The outbreak, which occurred during a 7-week stay beginning on July 2, infected 116 of the 152 boys, counselors, and staff members in attendance. No hospitalizations and deaths occurred in connection with the outbreak, and illnesses were moderate, the CDC said.
After evaluating the Wisconsin camp outbreak, the federal agency warned that transmissions at gatherings like this camp can only be preempted with a host of precautions: For instance, while participants were required to get screened for covid-19 in advance of the trip and wear masks while traveling, they did not need to quarantine for two weeks before and gathered in close contact. Because of those limited restrictions, a student who tested negative attended the camp, without knowing that a family member would later test positive, the CDC estimated.
“A robust covid-19 mitigation plan that included a full 14-day prearrival quarantine might have prevented introduction of SARS-CoV-2 in this setting,” according to the study, using the virus’s scientific designation. “As well, cohorting of attendees for 14 days after arrival might have permitted early containment of the outbreak.”
“Covid-19 spreads like wildfire when you bring a lot of people together in a relatively small space,” Julie Willems Van Dijk, deputy health services secretary for Wisconsin Department of Health Services, told the Milwaukee Journal-Sentinel. “If there was one person who was ill with covid-19, they easily spread that to everyone in their housing unit and then the nature of summer camp where you eat meals together, go swimming together, do activities together, sing around the campfire together — all of those activities are great spreading events.”
The study also found that 24 attendees who had reported having coronavirus antibodies before arrival, later did not test positive for the virus. But the CDC cautioned that there is not sufficient evidence “to determine whether the presence of detectable antibodies indicates protective immunity or how long such immunity might persist.”