Researchers at UC Santa Barbara, Oregon State University, University of Manchester and ETH Zurich are asking for a closer look at the ability of sunlight to neutralize SARS-CoV-2 after discovering that the most recent study on the matter was not up to the task.
The team compared data from a July 2020 study that reported the rapid inactivation of SARS-CoV-2 in sunlight in a laboratory setting, with a theory of coronavirus inactivation by solar radiation published just a month earlier.
They noted that the virus was inactivated up to eight times faster in experiments than the most recent theoretical model predicted. “The theory assumes that inactivation works by causing UV-B to reach the RNA of the virus, damaging it,” said professor of mechanical engineering at UC Santa Bárbara and lead author, Paolo Luzzatto-Fegiz, in a statement.
However, the research team felt that UV-B inactivation of RNA “may not be everything.” Scientists speculated that there it could be another mechanism at play besides the inactivation of RNA by UV-B rays, such as UV-A, the least energetic component of sunlight.
“People think that UV-A does not have much effect, but it may be interacting with some of the molecules in the medium,” explained Luzzatto-Fezig. These molecules, in turn, may be interacting with the virus, accelerating inactivation.
“So, scientists still don’t know what’s going on,” said Luzzatto-Fegiz; “Our analysis points to the need for additional experiments to separately test the effects of specific wavelengths and composition of the medium.”
If UV-A is able to inactivate the coronavirus, this can be very fruitful, as there are now many types of low-cost LED lamps that are even stronger than natural sunlight. UV-A can also be used to amplify the effect of air filtration systems with a relatively low risk to human health.