New mutations of COVID-19, such as the Delta strain, are “getting better” at transmitting through the air, a study has found.

People infected with a later variant of COVID-19 put 43 to 100 times more virus into the air when breathing than those who were infected with the original strains of the virus, according to the University of Maryland’s School of Public Health.

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.

“Our research indicates that the variants just keep getting better at travelling through the air,” Professor Don Milton said, “so we must provide better ventilation and wear tight-fitting masks, in addition to vaccination, to help stop spread of the virus.”

The just-released study examined the Alpha strain, which has since been displaced by the more dominant and even more highly transmissible Delta variant.

The amount of virus in the air coming from Alpha variant infections was 18-times more than could be explained by the increased amounts of virus in nasal swabs and saliva, the study found, highlighting the dangers of tiny aerosols carrying the infection.

“We know that the Delta variant circulating now is even more contagious than the Alpha variant,” Dr Milton cautioned.

To test whether face masks work in blocking the virus, the study measured how much SARS-CoV-2 was breathed into the air and tested how much less virus people sick with COVID-19 exhaled into the air after putting on a cloth or surgical mask.

Face coverings significantly reduced virus-laden particles in the air around the infected person, cutting the amount by about 50 per cent, researchers found.

Unfortunately, according to the study, the loose-fitting cloth and surgical masks didn’t stop infectious virus from getting into the air.

“The take-home messages from this paper are that the coronavirus can be in your exhaled breath, is getting better at being in your exhaled breath,” Dr Jennifer German, a co-author of the study, said.

“Using a mask reduces the chance of you breathing it on others.”

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