NETTAVISEN: – Sunlight kills the coronavirus. That is right.
Immunologist Anthony Fauci heads the National Institute of Allergy and Infectious Diseases (NIAID) and sits on the White House crisis group for the coronavirus. During an Instagram Live interview with actor Matthew McConaughey, he was asked about something the Americans have been debating for many weeks, namely whether sunlight kills the coronavirus.
– It does, and that is one of the reasons why it is much, much better to spend time outside in the sun than inside. It is always better to be outside than inside, Fauci states.
But is this true? If so, is it as simple as it sounds, that socializing in the sun prevents infection?
Sunlight deactivated the coronavirus
– Fauci is usually solid in his statements, says molecular biologist and professor Jan Terje Andersen at Oslo University Hospital.
Andersen refers to and recent study where researchers have conducted controlled experiments in the laboratory to study the effect of sunlight on the coronavirus.
– The study shows that the virus is quickly inactivated when it is dried in a liquid that mimics saliva on stainless steel material. This did not happen when the experiments were carried out in the dark for over an hour, says Andersen, and continues:
– The data indicate that sunlight has a large effect on the virus’ surface endurance, and hence exposure risk. The stability of the virus is altered by sunlight, and whether it is indoors or outdoors.
The study showed that the coronavirus was inactivated in less than 20 minutes in sunlight. Andersen emphasizes that the inactivation rate depends on both the intensity of the sunlight and the surface on which the virus lies.
Under typical summer conditions, it was shown that just over 90% of the virus was inactivated every 6.8 minutes in simulated saliva dried on a surface. For simulated sunlight that is representative of winter, the number was 14.3 minutes, he explains.
THE EXPERTS: Jan Terje Andersen, Fredrik Müller and Gunnveig Grødeland. Photo: UiO
Better to be out
Gunnveig Grødeland, researcher at the Department of Immunology and Transfusion Medicine at the University of Oslo, and Fredrik Müller, at the Department of Microbiology at OUS and the Department of Clinical Medicine at UiO, are also familiar with the study.
“Given the reservations that the experiment was carried out in an artificial setting, it can be seen that the UV rays in the sunlight appear to deactivate the coronavirus on a metal surface outdoors,” says Müller.
That said, all the researchers emphasize that the virus does not necessarily become inactivated when it is on the skin.
– The coronavirus is spread through droplet infection, ie droplets from, for example, saliva when we talk and cough. In that sense, sunlight will not have any significance for transmission between people, but if the drops fall on outdoor surfaces that we can touch again and become infected, then it does matter, says Müller.
It has previously been discussed whether dropping sunscreen, which protects against UV radiation, can limit the risk of infection. The researchers reject this.
– It’s getting too easy. Had that been the case, we would never have seen the same increase as we do in Florida, for example, says Grødeland, and continues:
– But we also know that heat deactivates the virus. The warmer, the higher the humidity – and then the coronavirus dies. So everything points in the same direction: It is better to be outdoors than indoors.
That said, there is one factor that is even more important, namely distance.
– The worst infection happens in the air, so if someone is close to you, either outside or inside, then neither heat nor sunlight helps, Grødeland concludes.
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