2 yıl önce

N95 masks back in the spotlight as Omicron rages. But why the flip-flop?

Several high profile figures in the US have advocated N95 masks and other respirators with reports suggesting that the country's health protection agency is considering a move in that direction.

Reuters

Confusion has prevailed over which mask to wear, if at all, and when. This could be linked to how the understanding of the virus has evolved.

The US Centers for Disease Control (CDC) could recommend highly protective N95 or KN95 masks for American citizens, marking another shift in its pandemic control policy at a time when the Omicron variant of the Sars-Cov-2 virus is tearing through nations at breakneck pace.

The agency is "currently actively looking to update its recommendations" and prescribe masks that "provide better filtration", the Washington Post has quoted an official privy to the discussions as saying.

The decision, if announced, would follow concerns flagged by experts that cloth masks — popular during the early days of the pandemic — do not provide enough protection against Omicron, and would be a hint for other nations in a matter of huge public interest.

"Cloth masks are little more than facial decorations. There's no place for them in light of Omicron," CNN medical analyst Dr Leana Wen told CNN Newsroom.

People should wear at least a "three-ply surgical mask", which is disposable, and that can be topped with a cloth mask, she told CNN in a phone interview.

Wen, whose Twitter bio identifies her as a public health professor, author and emergency physician, also said people should ideally wear N95 or KN95 masks in crowded places, as these could prevent tiny droplets carrying the airborne virus.

"Covid is airborne. Omicron is much more transmissible than earlier variants. We are in the middle of a viral blizzard. N95/KN95s are not in short supply. What's the delay, @CDCgov?," Wen asked on Twitter, adding that authorities in the US should have recommended high-quality masks "many months ago".

Cloth masks vs respirators

According to experts, cloth masks can filter large droplets to some extent, while N95 masks — if worn properly and fitted to the face — can protect against both tiny aerosols and larger droplets.

When approved by the US National Institute for Occupational Safety and Health, N95s, which are costlier, can "filter up to 95% of particles in the air", the CDC said on its website.

On the other hand, a 2019 study published in scientific journal PeerJ said an examination of the surface of 20 types of cloth masks found their pore size "ranged from 80 to 500µm" — bigger than particulate matters having diameters of 2.5µm or less (PM2.5) and 10µm or less (PM10).

To put things in context, the diameter of the Covid-causing virus could range from .05µm to .14µm. "...the length of the size tumours surrounding the outermost surface of Sars-Cov-2 can vary in length from 9 to 12 nm (.009-.012µm)," an article on Medical News said. It added that respiratory droplets are "typically 5-10 micrometres (µm) in length…"

Reuters

Omicron was estimated to account for 98.3 percent of total new coronavirus cases circulating in the country as of January 8, according to US CDC.

'Do it all'

"Masks should be used as part of a comprehensive strategy of measures to suppress transmission and save lives," the World Health Organization (WHO) said on its website, advocating a "Do it all" approach that also involves maintaining physical distancing, keeping rooms well ventilated, avoiding crowds, cleaning hands and coughing etiquette.

On another webpage, updated on January 5, WHO recommended for the public "three types of masks" — reusable non-medical masks of certain standards, disposable medical masks of certain standards and other types of well-fitting non-medical masks, including homemade multi-layered coverings when other options are not available.

But, the Washington Post said the updated CDC guidelines are expected to say that if people can "tolerate wearing a KN95 or N95 mask (used by healthcare professionals), you should".

Nonetheless, there is an argument that humble cloth masks are better than no face coverings at all.

Shifting paradigms

Since the beginning of the pandemic, confusion has prevailed over which mask to wear, if at all, and when.

Over time, there have been tectonic shifts in messaging: from masks are not necessary, to face coverings are voluntary, to the use of cloth masks and N95s by millions — it has been a whirlwind.

This is largely related to how the idea of how the virus infects has evolved: from surface transmission involving fomites (a doorknob for example), to the droplet route involving coughing or sneezing in the air, to tiny airborne particles released in the environment by the exhalation of infected people.

A little over two years into the pandemic, several European nations have already upgraded their masks in the face of an unsparing variant, an emergency move at a time when research is suggesting that Omicron could be 2.7 to 3.7 times more infectious than the Delta variant even among vaccinated people.

Notwithstanding protests by people opposing face coverings, a clamour has been growing among a section of experts, healthcare professionals and politicians in the US, which has overcome the supply shortage of personal protective equipment, including surgical masks and respirators such as N95s, during the onset of the pandemic.

"Every American deserves a high-quality N95 mask to protect themselves from this virus," US senator Bernie Sanders tweeted.

And in another tweet, he sought to explain why not "all masks are created equal".