Researchers of the Higher Council for Scientific Research (CSIC), belonging to the Ministry of Science, have written a report that compiles the current state of knowledge about how the transmission of the SARS-CoV-2 virus, causing the disease COVID-19, in spaces for bathing and other aquatic activities.

The report has been prepared at the request of the Secretary of State for Tourism within the framework of the action protocols being prepared by the Ministry of Industry, Commerce and Tourism for the resumption of activity in the tourism sector.

As an introduction, the authors emphasize that among the possible routes of contagion in the environments referred to in the report (swimming pools, beaches, rivers, etc.), the main route of transmission of SARS-CoV-2 is through secretions. respiratory that are generated by coughing and sneezing and person-to-person contact, so general recommendations for any other place should be maintained.

In addition, the crowds that can occur in swimming pools and beaches, as well as common use objectsThey can continue to serve as a contagion mechanism. Other possible routes of contagion reviewed are those derived from the presence of virus in sewage that can reach bathing water bodies and the survival of the virus from bathers in waters, sands and bordering surfaces.

The report has been written by seven researchers from CSIC centers: Ana Allende, from the Center for Edaphology and Applied Biology of Segura (CEBAS-CSIC), Alice of Andrés, from the Madrid Institute of Material Sciences (ICMM-CSIC), Antonio Figueras, from the Institute of Marine Research (IIM-CSIC), Gloria Sánchez, from the Institute of Agrochemistry and Food Technology (IATA-CSIC), Joan Grimalt and Teresa Moreno, from the Institute of Environmental Diagnosis and Water Studies (IDAEA-CSIC), and Carlos Prieto, Deputy Vice President of Scientific and Technical areas of the CSIC.

The researchers have used the scientific literature available to date to give a series of indications and recommendations for spaces for recreational water activities.

Considerations in recreational aquatic spaces

The report notes that in recreational activities, SARS-CoV-2 infection by contact with water from standard bath conditions is highly unlikely. However, these activities generally involve a loss of the recommended measures of social distancing.

In pools and spa, the use of disinfecting agents It is widely implemented in order to avoid microbial contamination of the waters by the influx of users, and this measure should be sufficient to inactivate the virus.

Aerosols generated in a Spa or in a medicinal water installation they will have the same disinfection characteristics as the bath waters of these facilities. In those cases where the environment of the facilities is maintained at high temperatures, such as in saunas and steam baths, it is expected that, due to the high temperature (> 60 ºC), the survival of the virus is reduced.

On the other hand, regarding the sea ​​water, the report argues that, although there are currently no data on the persistence of SARS-CoV-2, the dilution effect and the presence of salt are factors that probably contribute to a decrease in viral load and its inactivation by analogy to what it happens with similar viruses.

However, the survival of SARS-CoV-2 in rivers, lakes, pools of fresh and untreated water is superior compared to swimming pools and salt water and, therefore, precautionary measures must be taken to avoid crowds, these being the most inadvisable aquatic environments in relation to other alternatives.

Other factors that may be of concern are the prevalence of virus in the sand present on beaches or riverbanks. Although there are no experimental studies in this regard, the combined action of seawater salt, solar ultraviolet radiation and the high temperature that can reach the sand are favorable for the inactivation of pathogens. The report also emphasizes that any form of disinfection of beach sand must be environmentally friendly and disinfection is not recommended with standard procedures for urban public spaces.

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