COVID-19 outbreak at a summer camp in Piedimont region in 2021: description, lessons learned
and recommendations for future summer camps
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.
Results
Among the 187 study participants, the median age was 14 years (range: 6-45). Seven days after arrival at the
camp, 8 campers developed symptoms and tested positive. The overall AR was 33.7% (63 out of 187), and
34.2% (50/146) for campers and 31.7% (13/41) for staff, respectively. Among those with available symptoms
information, 72% (36/50) were asymptomatic at the time of testing. Only 17.1% of campers had direct contact
with blood relatives from other subgroups. The AR of participants using a bus was 36.2% (59/163) with an RR
of 1.18 (95% CI = 0.51-2.73,) and the AR of those belonging to a subgroup was 35% (62/177) with an RR of 3.5
(95% CI = 0.54-22.7). For personnel, participation to a subgroup gave an AR of 38.7% (12/31) and an RR of 3.87
(95% CI = 0.57-26.18). All but four subgroups had a high AR (>33,3).
Conclusions
Getting tested prior to traveling and campers separation into low-contact subgroups was not sufficient enough
to avoid a high number of infections in this summer camp. Analysis did not allow the identification of an index
case or helped to understand whether the outbreak originated from the attendees who travelled on the same bus.
The high AR observed in all subgroups suggest that there was frequent contact between attendees belonging to
different subgroups. Sharing of common areas such as the canteen and contact between attendees are possible
factors that have contributed to the spread of the outbreak. The experience gained by the analysis of this data was
used for the review of measures for the organization of summer camps in 2022
