Coronavirus: sea, river, lake… can Covid-19 be spread through water?

Published by Caroline de Sortiraparis · Published on May 22th, 2020 at 11:59 a.m.
While many beaches have reopened and many people are counting on enjoying nature again and swimming in the sea, lake or river, is there any risk Covid-19 can spread through water? Let’s have a look on the matter.

Fance has lifted confinement this past May 11th. Since then, many stores have been welcoming customers again, so have parks and gardens, but only in departments in green area. Yet, restaurants, cafés and bars will reopen later. Many beaches have also been authorized to reopen, for seaside lovers’ greatest joy.

So, with this beautiful weather and summer upon us, many people are tempted to bathe and get a breath of fresh air by the sea, lakes, and rivers. But can covid-19 be spread through water?

According to the French Haute Autorité de la Santé Publique [Health High Authority], “the assessment of the scientific literature does not enable to confirm today the presence of infectious SARS-CoV-2 in the waters in natural environment. The HCSP says health control only relying on bacteria settings, it shows a contamination by release of fecal matter, but no prediction of the presence of the infectious SARS-CoV-2 virus”.

As the HCSP says, “in cases of swimming and their environment, the greatest respect of social distancing measures is a vital and priority element of general prevention of infection by SARS-CoV-2”.

Same call for the Health Minister who has been saying so far “no contamination through water case has been reported. This disease is spread between humans through droplets (cough, sneeze, hands spoiled by droplets)”.

For the record, this past April, the City of Paris announced the non-potable water grid use was suspended after traces of Covid-19 were found in tested sampling points.

As France Info unveils it, several studies about the spread of SAR-CoV-2 through water are being carried out. Let’s have a look on those studies.

No trace of the virus in shells and sea water

In order to know if sea water can be contaminated by the SARS-CoV-2 virus, Ifremer – the French Research Institute for the Exploitation of the Sea – has carried out assessment on shells (oysters and mussels) collected in several spots in Normandy, Brittany, the Atlantic Coast, and the Mediterranean.

The first results shared on May 18th have come back negative: “No trace of coronavirus […] has been detected in samples of analyzed sea water and mollusks” the Institute said, adding that some samples have been potentially spoiled by release from water treatment plants. Yet, results have been negative. 

Tweet reads: “Is SARSCoV2 in sea environment and shells on the French coast? The Ifremer presents the first results

According for Soizick Le Guyader, searcher at the Nantes Ifremer, “SARS-CoV-2 remains very little released in feces. A very weak percentage of the population has been infected. Wastewater is treated and even though they arrive spoiled to the sea, they are then highly diluted” she explained on France Info.

Careful though because these samples have been analyzed during the French lockdown. They will be controlled in the next days.

As another study reminds it, this time revealed by the Spanish Superior Council of Scientific Investigation, “The main ways SARS-CoV-2 is spread on beaches, by rivers, lakes and pools goes through the respiratory secretions caused by coughing, sneezing and contact between people”.

What about swimming pools?

According to scientists, there is barely any risk to be contaminated by Covid-19 in treated water, and then in swimming pools because of “the use of disinfecting agents widely set up”. By the way, according to the Haut Conseil de la Santé Public report, disinfecting with chlorine is “effective” on similar viruses.

The Haut Conseil de la Santé Publique says that “no study about the survival of the SARS-CoV-2 in swimming pool water is accessible so far. The water in swimming pools does not seem to be a suitable environment for the survival and development of viruses. Viruses with an envelope – flu viruses or coronaviruses – are too fragile and cannot survive long in the outside to be spread through swimming pools”. By the way “viruses cannot replicate outside tissues of the host and cannot multiply in the environment. Consequently, the presence of viruses in a swimming pool is the result of direct contamination by bathers who can release viruses in unintentional fecal matters or the release of body fluids such as saliva, mucus or vomit” the HCSP adds.

Even though containment exit has started, swimming pools are still closed to the public. A decision about their reopen is said to be made on June 2. How come? The difficulty to have social distancing measures upheld, especially in changing rooms and bathrooms.

And for sauna fans, Spanish scientists are rather reassuring since the temperature being above 60°C (140°F) in those places, it drastically lowers the survival chances of a virus.

Lakes and rivers are more worrying

The survival of SARS-CoV-2 in non-treated water can be bigger” to the one in treated or salt water the Spanish Superior Council of Scientific Investigation shared by France Info. As for “rivers, lakes, freshwater pools and non-treated [water]” specialists say they are the “least recommended water environments”.

The spread of the virus through water also worries other countries such as Australia. This week, a study has been launched in Melbourne to find any trace of Covid-19 in wastewater.

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