SARS-CoV-2 prevalence and transmission in swimming activities: results from a retrospective cohort study

Abstract

There is an urgent need for research on the epidemiology of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causing corona virus disease 2019 (COVID-19), as the transmissibility differs between settings and populations. Here we report on a questionnaire-based retrospective cohort study of the prevalence and transmission of SARS-CoV-2 among participants in swimming activities in Denmark in the last five months of 2020 during the COVID-19 pandemic. Eight of 162 swimming activities with a SARS-CoV-2 positive participant led to transmission to 23 other participants. Overall, the percentage of transmission episodes was 4.9% (competitive swimming 8.9%; recreational swimming 1.3%). Overall, the incidence rate of transmission was 19.5 participants per 100.000 pool activity hours (corresponding values: 43.5 and 4.7 for competitive and recreational swimming, respectively). Compliance with precautionary restrictions was highest regarding hand hygiene (98.1%) and lowest in distancing personal sports bags (69.9%). Due to low statistical power, the study showed no significant effect of restrictions. Insight into the risk of transmission of SARS-CoV-2 during indoor swimming is needed to estimate the efficiency of restrictive measures on this and other sports and leisure activities. Only when we know how the virus spreads through various settings, optimal strategies to handle the COVID-19 pandemic can be developed.

COVID-19 transmission during swimming-related activities: a rapid systematic review

“…Restrictions included distancing, personal hygiene, limiting use of shared equipment, limiting physical activity around the pool area, and raising chlorine content. The authors reported that this analysis had low statistical power [15]. We judged the study as having serious risk of bias and providing very low certainty evidence.…”

“…We excluded 26 studies for the following reasons: not about swimming (n = 5), not outcome of interest (n = 12), not eligible study design (n = 6), duplicates (n = 1), full text not found (n = 2) (see Additional file 1: Appendix 2a for more details). This resulted in three eligible studies for the review of association [13][14][15].…”

“…The authors hypothesized that transmission could have resulted from other activities during the training camp (e.g. sleeping in dormitories, dining and socializing together) [15].…”