As the Omicron variant spreads rapidly across the country, prominent public health officials in the United States have increasingly emphasised the limitations of cloth face masks, urging the use of more effective respirator masks such as N95s, according to the Washington Examiner. This is a shift in messaging from earlier in the pandemic.

Officials encouraged the use of cloth masks in the spring of 2020 as a desperate measure to slow the spread of Covid-19 after previously recommending against masks and continued to boost them in the months after. Now, though, more experts are saying that the masks are not helpful, the report said.

"Cloth and surgical masks do absolutely nothing for protection from ambient virus," said Chad Roy, a microbiologist at Tulane University School of Medicine, referring to the virus spreading through the air.

"All this song and dance of wearing cloth masks with some presumption that you're being protected from ambient virus is completely and positively 100 per cent counter to how masks and respirators work."

Evidence of the the N95's superiority to the cloth mask has been well-documented.

In 2015, for example, before the onset of the pandemic, scientists from Australia, Vietnam, and China concluded that healthcare workers "should not use cloth masks as protection against respiratory infection. Cloth masks resulted in significantly higher rates of infection than medical masks, and also performed worse than the control arm".

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"The use of an N95 does give you some protection in a bidirectional manner, meaning that if you're using an N95 without a one-way valve for exhalation... you're protected from not only ambient aerosol of a particular size, as well as exhalation if you are ill, so it does double duty in that regard," Roy said.

President Joe Biden's administration announced this week that it would prioritize distributing 400 million free high-quality respirators to be made available through local pharmacies and community health centres.

The millions of N95s would come out of the 750 million masks currently stored in the Strategic National Stockpile.

The rollout is expected to begin early next month, the report said.