The coronavirus has evolved to become more airborne, a possible explanation as to why variants like alpha and delta are more transmissible than the original strain, The New York Times reports.
While researchers have already established that COVID-19 is mostly spread by coming into contact with large respiratory droplets and aerosols that travel through the air, two new findings indicate the virus has evolved to become more efficient at airborne travel.
In the first study, published in the preprint server bioRxiv, researchers found small aerosols travel much farther than large droplets and that the alpha variant was much more likely to spread through the air.
A separate study published in Clinical Infectious Diseases Sept. 14 also focused on alpha. It found people infected with the strain exhale about 43 times more virus in small aerosols compared to those infected with earlier strains.
Scientists on this study concluded, "SARS-CoV-2 is evolving toward more efficient aerosol generation and loose-fitting masks provide significant but only modest source control. Therefore, until vaccination rates are very high, continued layered controls and tight-fitting masks and respirators will be necessary."
While both of the studies focused on alpha, the findings may also reveal why delta is so transmissible.
"It really indicates that the virus is evolving to become more efficient at transmitting through the air," Linsey Marr, PhD, an airborne virus expert at Virginia Tech in Blacksburg, told the Times. "I wouldn't be surprised if, with delta, that factor were even higher."
Dr. Marr was not involved in the two new studies.