Results of a rapid systematic review found a lack of robust evidence on the association between the risk for SARS-CoV-2 transmission and engaging in swimming-related activities during the COVID-19 pandemic. These findings were published in BMC Infectious Diseases.

In this rapid systemic review, researchers searched publication databases for studies that investigated the effect of swimming-related activities on the risk for SARS-CoV-2 transmission. A total of 3 studies met the inclusion criteria. In addition, the researchers reviewed 50 documents that included guidelines for decreasing the risk for SARS-CoV-2 transmission at facilities with swimming-related activities.

Study 1 was a retrospective questionnaire-based study which recruited patients from indoor swimming clubs in Denmark between August and December 2020. Among a total of 162 episodes in which an individual with SARS-CoV-2 infection participated in a swimming activity, 8 were found to be related to transmission of the disease in 23 individuals, indicating a transmission rate of 4.9%. After stratification by type of swimming activity, the researchers noted that the rate of SARS-CoV-2 transmission was 43.5 and 4.7 per 100,000 activity hours for competitive and recreational swimming activities, respectively.


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Study 2 was an epidemiologic study conducted early in 2020 in Wuhan, China that investigated a public bath-related outbreak of COVID-19 in which 12 individuals tested positive for SARS-CoV-2-infection after 1 individual took a public bath 2 consecutive days. Of the 12 individuals who were infected, 10 were other bathers and 2 were staff members of the public bath. Following the transmission event, 1 of the infected bathers transmitted the virus to an additional 19 individuals. In addition, 1 of the infected staff members also subsequently transmitted the virus to an additional 41 individuals, 7 of whom were other bathers. In regard to the increased rate of SARS-CoV-2 transmission events that occurred outside the public bath center, the researchers hypothesized that the high temperature and humidity inside the public bath center decreased the risk for SARS-CoV-2 transmission.

Study 3 recruited 9 individuals hospitalized with SARS-CoV-2 infection in China who frequented the same public bath center. The public bath center included a swimming pool, showers, and a sauna. Among the 9 individuals who were infected at the public bath center, 1 reported using only the showers, 7 reported using the sauna, showers, and swimming pool, and 1 was a staff member. In regard to the findings of study 3, the researchers concluded that COVID-19 transmission “showed no signs of weakening in warm and humid conditions.”

Among the 50 guideline documents included in the analysis, 82% specifically addressed swimming-related activities, 80% were issued by governmental organizations, 62% were issued by organizations in the United States, and 94% focused on only pool-related activities.

The researchers found that most (88%) documents advised that facilities with swimming-related activities decrease their maximum occupancies by50% and institute social distancing measures such as physical barriers, visual cues, and changing the layout of spaces. In addition, 90% of guideline documents also tended to emphasize personal hygiene practices, including hand-washing, respiratory etiquette, and avoiding touching one’s face with unwashed hands. Of note, there were significant differences between the documents in regard to the optimal frequency for cleaning high-touch surfaces. Further review showed that 63% of the documents recommended against the use of masks inside the pool or in damp areas.

Most guidelines (90%) advised for COVID-19 screening protocols and prevention measures, such as isolating individuals following a potential exposure to SARS-CoV-2 and those with COVID-19-related symptoms. Only 3 guidelines addressed vaccination, 2 of which recommended that facilities institute the same preventive measures regardless of an individual’s vaccination status.

This study was limited by the lack of mechanistic or environmental studies and the inclusion of guidelines which focused on differing stages of the COVID-19 pandemic.

The researchers concluded that additional “evidence [is needed] to support an analytical framework addressing the different activities and exposures, mode of transmission, and mitigating and modifying factors for COVID-19 [transmission] in swimming-related activities.”

Reference

Yaacoub S, Khabsa J, El-Khoury R, et al. COVID‑19 transmission during swimming‑related activities: a rapid systematic review. BMC Infect Dis. 2021;21(1):1112. doi:10.1186/s12879-021-06802-4