Mechanics of SARS-CoV-2 spread in a sleep-away camp

1. Analysis of transmission dynamics of a COVID-19 outbreak at a Georgia summer camp reveals rapid viral spread with high attack rates.

2. Data emphasizes the inadequacy of COVID-19 testing without adherence to proper social distancing and quarantine procedures.

Evidence Rating Level: 2 (Good)

Study Rundown: While the transmission behavior of the SARS-CoV-2 virus is still being modeled, data to date from juveniles has proven inconsistent. In this retrospective cohort, a large outbreak in a summer camp in Georgia in June 2020 involving more than half of the camp’s population was analyzed to better understand viral transmission dynamics. The overall attack rate (AR) was 56%, despite the fact that a negative SARS-CoV-2 test was required within 12 days prior to arrival. The AR increased with extended duration of stay in the camp. Widespread close contact between different cabin members, daily singing and cheering, and low rates of mask use likely all contributed to significant viral spread. Interviews were subject to recall bias due to the fact that they were conducted several weeks after camp ended. This study provides insight into the ability of SARS-CoV-2 to rapidly spread in dense juvenile populations when few mitigations strategies are implemented. Additionally, it highlights the inability of one-time, pre-attendance SARS-CoV-2 testing without a mandatory quarantine period to prevent outbreaks.

Click to read the study in Pediatrics

Relevant Reading: Preventing and Mitigating SARS-CoV-2 Transmission — Four Overnight Camps, Maine, June–August 2020

In-Depth [retrospective cohort]: 627 campers, trainees, and staff members were included in the analysis (56% female, 94% white). Three groups of individuals were studied: trainees (only attended orientation), staff members (attended orientation and worked during camp), and campers. At the start of camp, there were 10 case patients spread out across 7 different cabins; 8 of these were community-associated and 2 were camp-associated that likely spread from staff members who attended pre-camp orientation. Of 404 campers and staff ages 6 to 21 with available data for covariates of interest, staff members were 4.5 times as likely to become a camp-associated case patient compared with trainees (95% CI = 2.7–7.5), adjusting for age group, duration of stay, staying in a cabin with a case patient when arriving at camp, and contact with people outside their cohort. Campers were 3.8 times as likely to become a camp-associated case patient compared with trainees (95% CI = 2.6–5.5), adjusting for the same covariates. The instantaneous reproduction number (10.1) was highest during peak occupancy, indicating increasing probability of transmission with increasing population density. For those who were at camp for at least 7 days, the attack rate was as high as 75%. 29 out of 31 cabins had at least 1 case patient. Most attendees did not wear masks (15% of staff, 5% of campers); thus, the effect of masks in preventing transmission was unable to be studied.

Image: PD

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