The new coronavirus, responsible for the Covid-19 pandemic, weakens in a hot and humid atmosphere as well as in the sun’s rays, according to a study by the United States government presented Thursday at the White House. “Our most striking observation to date is the powerful effect that sunlight seems to have on killing the virus, both on surfaces and in the air”said senior Homeland Security official Bill Bryan. “We have seen a similar effect on both temperature and humidity. Rising temperatures or humidity, or both, are generally less favorable to the virus. ”, added the official, presenting the preliminary results of this study.
Scientists have wondered since its appearance on the possibility that the new coronavirus might weaken with increasing temperatures, that is to say with the arrival of summer in the northern hemisphere. “We have identified some of the weak links in the chain of virus transmission. We have identified that heat and humidity are weak elements in this chain. We identified that sunlight, UV rays were a weakness in this chain ”insisted Bill Bryan.
“We have identified some of the weak links in the chain of virus transmission. We have identified that heat and humidity are weak elements in this chain. We identified that sunlight, UV rays were a weakness in this chain ”said Bill Bryan, a science and technology expert with the Department of Homeland Security.
Reduced lifespan
In support of his claims, the expert presented some figures from this study conducted at the National Biodefense Analysis and Countermeasures Center. According to these data, a half-life of the virus, namely the time necessary to halve its power, is 18 hours with a temperature between 21 and 24 degrees celsius, with 20% humidity on a non-porous surface . This includes surfaces such as door handles. But this half-life is reduced to six hours when the humidity increases to 80%, and only to two minutes when sunlight is added to the equation.
When the virus is suspended in the air, the half-life is one hour with a temperature of 21 to 24 degrees Celsius and 20% humidity. With the same humidity, the same temperature, but with the addition of sunlight, this time drops to a minute and a half. Bill Bryan concluded that summer conditions could create “An environment in which transmission can be reduced”. But this does not mean that the pathogen is eliminated entirely. And the results of this one study cannot justify lifting social distancing measures currently in effect in the United States, he warned.
Previous studies had shown that the virus survived better in cold and dry weather conditions rather than hot and humid. The lower rate of spread of the disease in countries in the southern hemisphere where it is the beginning of autumn, with the weather still warm, also seems to support this theory. Australia, for example, has yet registered only 6,600 known cases of coronavirus and only 75 deaths, figures far below the countries of the northern hemisphere. But the coronavirus has also proven to be deadly in places like Singapore when the temperatures were summer, calling into question a link between the behavior of the virus and environmental factors.
Donald Trump said the researchers’ observations should be interpreted with caution. However, he also said he saw the justification for comments made later on a possible decline in the epidemic during the summer. “I mentioned that maybe the virus would go away with heat and light. But people didn’t like this statement very much. “said the American president during the press briefing. He noted, however, that the United States could be in a better position with the arrival of summer. “If the heat is good, if the sunlight is good, I think it’s a very good thing”Vice President Mike Pence called the presentation ““Encouraging”.
The White House chief said Thursday that Americans may have to maintain social distancing until early summer, although some states are showing signs of progress in fighting the epidemic. However, the American health authorities consider that even if the number of contaminations with the new coronavirus slows down during the summer, the infection rate will probably increase again during the fall and winter, as is the case with viruses. seasonal.
– .
