Researchers of the Higher Council for Scientific Research (CSIC), belonging to the Ministry of Science and Innovation, they have drafted a report It compiles the current state of knowledge about the transmission of the SARS-CoV-2 virus, which causes the COVID-19 disease, 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 the general recommendations for any other place should be maintained.
In addition, the crowds that can occur in swimming pools and beaches, as well as objects in common use, can continue to serve as a mechanism of contagion. Other possible routes of contagion reviewed are those derived from the presence of the virus in wastewater that can reach bathing water bodies and the survival of the virus from bathers in waters, sands and neighboring 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), Alicia de Andrés, from the Institute of Material Sciences of Madrid (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 Presidency 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 standard bath conditions for water is highly unlikely. However, these activities generally involve a loss of the recommended measures of social distancing.
In swimming pools and spas, the use of disinfecting agents 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 facility will have the same disinfection characteristics as the bathwater in these facilities. In those cases where the environment of the facilities is kept at high temperatures, such as in saunas and steam baths, it is expected that, due to the high temperature (> 60ºC), the survival of the virus will be reduced .
For its part, regarding sea water, the report maintains 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 are likely to contribute to a decrease in viral load and its inactivation by analogy to what happens with similar viruses.
However, the survival of SARS-CoV-2 in river, lake, freshwater and untreated water is superior compared to swimming pools and salt water and, therefore, precautionary measures should be taken to avoid crowds. These are the most inadvisable aquatic environments in relation to other alternatives.
Other factors that may be of concern are the prevalence of the 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.
