A boy who arrived at a Wisconsin faith-based summer camp after falsely testing negative for COVID-19 likely spread the virus to at least 116 people, according to a new report by the Centers for Disease Control and Prevention released on Thursday. The outbreak at the high-school retreat between July 2 and Aug. 11 reinforced the importance of a “multicomponent COVID-19 mitigation plan” including “prearrival quarantine and testing, cohorting, symptom monitoring, early identification and isolation of cases, mask use, and enhanced hygiene and disinfection practices,” the CDC said. All of the outbreak-related illnesses were mild to moderate, and none of them, fortunately, required hospitalization. No deaths occurred, the CDC said.

“COVID-19 spreads like wildfire when you bring a lot of people together in a relatively small space,” said Julie Willems Van Dijk, Wisconsin’s deputy health services secretary. “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.”