A new study has found covid-19’s new strains is evolving toward more efficient aerosol generation and loose-fitting masks provide significant but only modest source control.
The research suggests the need for better ventilation and tight-fitting masks, in addition to widespread vaccination to help stop spread of the virus.
Until vaccination rates are very high, continued layered controls, including improved ventilation, increased filtration, UV air sanitation, and tight-fitting masks are critical to protect people in public-facing jobs and indoor spaces, researchers say.
The University of Maryland study showed people with the new covid strains such as Delta put 43 to 100 times more virus into the air than people infected with the original virus strain.
The researchers also found that loose-fitting cloth and surgical masks reduced the amount of virus that gets into the air around infected people by about half.
The study was published in the Clinical Infectious Diseases journal and it provides further evidence of the importance of airborne transmission.
The researchers said the Delta variant circulating is even more contagious than the Alpha variant.
Their study indicated the variants just keep getting better at travelling through the air, so better ventilation and tight-fitting masks, in addition to vaccination, are all needed to stop the spread.
The amount of virus in the air coming from Alpha variant infections was much more, 18 times more, than could be explained by the increased amounts of virus in nasal swabs and saliva.
The virus in saliva and nasal swabs was increased in Alpha variant infections. Virus from the nose and mouth might be transmitted by sprays of large droplets up close to an infected person.
But the Maryland study shows that the virus in exhaled aerosols is increasing even more.
The major increases in airborne virus from Alpha infections occurred before the Delta variant arrived and indicate that the virus is evolving to be better at travelling through the air.
Face coverings in the study significantly reduced virus-laden particles in the air around the person with covid-19, cutting the amount by about 50 percent.
Unfortunately, the loose-fitting cloth and surgical masks didn’t stop infectious virus from getting into the air.