ABSTRACT
Introduction: In August 2021, an outbreak of coronavirus disease 2019 (COVID-19) occurred in a summer camp in Piedmont region, Italy, affecting primarily campers aged 16 years. We conducted a retrospective cohort study among campers and personnel (attendees) to determine the attack rate (AR), evaluate possible factors associated with transmission and propose recommended measures for the organization of future summer camps. Materials and methods: A de-identified database including demographic, role of attendees, cohorting, means of transportation to the camp, inter-camper interactions, SARS-CoV-2 testing results and symptomatology was used. All analysis data came from a collection of data carried out by the organizing private company and the information related to the mitigation protocol put in place was provided by the health care personnel. All campers were asked to have an antigen/molecular test within 72 hours before departure. Nine dedicated buses departed from different Italian regions towards the camp. All travellers wore a surgical mask during the trip. Upon arrival, regardless of the bus used, the campers were divided into 11 subgroups with no further contact between them unless they were blood relatives. No SARS-CoV-2 screening tests were scheduled for campers after arrival and during the camp period. On the other hand, personnel had a screening test at each shift change. During the camp period, antigen tests were performed at cases with symptoms suggestive of infection. Only attendees enrolled in the private company and those who received at least one test since arrival at the camp were considered in the study. We calculated overall AR and relative risk (RR) along with specific, transmission-focused risk factors.