The idea that the new coronavirus could decrease in intensity during the summer has long been debated. In fact, it is the reaction of the coronavirus to high temperature and humidity. One study found that it weakens in such an environment.

The research was conducted by the National Biodefense Analysis and Countermeasures Center at the request of the US Government. Specialists observed a regressive reaction of the virus to strong sunlight.

High heat and humidity could weaken the coronavirus

In fact, the sun kills the virus on surfaces and in the air. "Our most striking observation to date is the strong effect that sunlight appears to have on killing the virus, both on the surface and in the air," a Homeland Security spokesman, Bill Bryan, wrote Thursday. 

"I saw a similar effect on both temperature and humidity. The increase in temperature or humidity or both is generally less favorable to the virus, "the official added.

Does the virus weaken when summer comes?

Scientists have been researching the possibility of the virus weakening since the temperature rose with the arrival of summer in the northern hemisphere.

"We identified one of the weak links in the chain of virus transmission. We have identified that humidity and heat are weak elements in this chain. We have identified that sunlight, UV rays are a weakness in this chain ", insisted Bill Bryan, an expert in Science and Technology at the Department of Homeland Security.

80% humidity is almost fatal for Covid-19

To support his claims, the expert presented some data in figures from the study - conducted by the National Biodefense Analysis and Countermeasures Center.

According to these data, the half-life of the virus - the time required to halve its power - is 18 hours at a temperature between 21 and 24 degrees Celsius and a humidity of 20%, on a non-porous surface. These are surfaces such as door handles.

But this half-life is reduced to six hours, when the humidity level rises to 80% and to only two minutes when sunlight intervenes in the equation.

When the virus is suspended in the air, the half-life is one hour, at a temperature of 21 to 24 degrees Celsius and 20% humidity.

At the same humidity level and temperature, but in sunlight, this duration decreases to a minute and a half. Bill Bryan concludes that summer could create "an environment in which transmission can be reduced." But that doesn't mean the pathogen is completely eliminated.

And the results of this study alone cannot justify a lifting of the social distancing measures in place in the United States, he warned. Previous studies have shown that the virus survives better in cold and dry weather than in heat and humidity.

However, US health authorities believe that even if the number of new coronavirus infections decreases over the summer, the level of infection is likely to rise again in the fall and winter - as is the case with seasonal viruses.

Fifty-two people - most of them migrants from sub-Saharan Africa - died in the sinking of a boat off Tunisia, according to a latest report announced on Thursday by a Tunisian health official, reports AFP.

According to testimonies collected by the Tunisian authorities, the migrants were on board a clandestine boat that left the Tunisian city of Sfax (center-east) for Italy, on the night of June 4 to 5, with 53 people on board.

 Fishermen have been alerting authorities since Tuesday, after discovering bodies floating off the island of Kerkennah, near Sfax.

 Some of these migrants have begun to be buried, Sfax Regional Health Director Ali Ayadi told AFP.

 On Thursday, 17 other bodies were found, and the death toll rose to 52, including at least 24 women, he said.

 One person is reported missing.

The victims are people from sub-Saharan Africa, according to the first forensic findings and the testimonies of other migration candidates.

 The captain of the boat, a 48-year-old Tunisian from Sfax, was among the victims, and a court ruled that it was a "shipwreck".

 An investigation has been opened to identify the organizers of this clandestine crossing, accordingly.