Researchers from UC Santa Barbara, Oregon State University, University of Manchester and ETH Zurich ask to take a closer look at the ability of sunlight to neutralize SARS-CoV-2 after finding that the most recent study on the matter was inadequate.
The team compared data from a July 2020 study that reported rapid inactivation of SARS-CoV-2 by sunlight in a lab setting with a theory of inactivation of the coronavirus by solar radiation published just a month earlier.
They noted that in experiments the virus was inactivated as much as eight times faster than the most recent theoretical model predicted. “The theory holds that inactivation works by allowing UV-B to hit the virus’s RNA and damage it,” UC Santa Barbara professor of mechanical engineering and lead author Paolo Luzzatto-Fegiz said in a statement.
However, the research team felt that RNA inactivation by UV-B “may not be the whole story.” The scientists speculated that there could be another mechanism besides RNA inactivation by UV-B rays such as UV-A, the less energetic component of sunlight.
“People don’t think UV-A has much of an effect, but it can interact with some molecules in the medium,” explains Luzzatto-Fezig. Those molecules, in turn, can interact with the virus, accelerating inactivation.
“So scientists don’t know what’s going on yet,” said Luzzatto-Fegiz; “Our analysis indicates the need for additional experiments to test the effects of specific wavelengths of light and media composition separately.”
If UV-A turns out to be able to inactivate the coronavirus, it could prove very fruitful as there are now many types of cheap LED lamps that are even stronger than natural sunlight. UV-A can also potentially be used to enhance the effect of air filtration systems with a relatively low risk to human health.