Dr. Abraar Karan has been urging people to wear “better masks” for roughly 18 months.

He did it during the first COVID-19 surge in the spring of 2020.

He did it last winter.

He did it as the delta variant began to ascend.

And now, as the omicron variant pushes COVID-19 infection rates to records heights and increases the load on an already-strained health care system, Karan says that upgrading your mask to a N95 or KN95 respirator is as important as ever.

In an interview Tuesday with New York magazine, the Stanford infectious disease doctor — and former resident at Brigham and Women’s Hospital and Harvard Medical School — said the extremely transmissible omicron variant means it’s “far more likely” that individuals could get COVID-19 from a brief interaction “like being in the grocery store for a few minutes or being face-to-face with somebody for a conversation.”

While previous variants were generally not transmitted through brief contacts, health experts say the omicron variant has officially put the old “15 minutes within six feet” rule to bed.

“It changes my risk calculus,” Karan told New York.

Even before as much was known about the omicron variant, Karan was sounding the alarm and urging people to get better masks. Not only are N95 and KN95 masks more protective, but research has found that cloth masks — such as face masks, neck gaiters, and bandanas — vary in their effectiveness at containing particles that are transmitted into the air when an individual exhales.

NIOSH authors pre-print on how well cloth masks perform for source control of aerosols “The source control collection efficiencies for the cloth masks ranged from 17% to 71% for coughing and 35% to 66% for exhalation.” Might be important @cdcgovhttps://t.co/qm0zBVx68C pic.twitter.com/hX3Jy3D8wB

“You really need melt-blown polypropylene, which you find in surgical masks and N95s, to stop these small particles,” Karan told New York.

“The material is basically melt-blown polymers, like polypropylene, which form this complex sort of webbing which is then electrostatically charged, and that pulls the particles in when you’re inhaling and exhaling,” he said. “Cloth masks are often just woven thread and other materials that don’t have that design.”

That doesn’t mean cloth masks are useless, especially when multiple people in a space are wearing them.

Harvard exposure science professor Joseph Allen tweeted Wednesay that two people wearing 50 percent effective cloth masks equates to 75 percent combined efficacy.

“It’s wrong to say these ‘don’t work’; correct to say they are ‘less effective’ than N95,” Allen wrote, adding surgical masks also provide a large degree of protection, even if it’s less than a higher filtration respirator.

4. Surgical masks work I cringe when I see 'experts' say these masks leak so they don't work. Yes, some aerosol escapes out the side, but direction of airflow matters. Reducing the plume in the speaker's cone of emissions as they directly interact with others is key. And…

…when someone say surgical masks don't work in hospitals, they're ignoring the benefit of reducing the aerosol jet in front of the person and thinking of PPE in isolation, ignoring airflow dynamics in the space. N95s better? Sure, and should be norm for high-risk areas.

Karan tweeted agreement with Allen’s assessment Wednesday. Still, with many localities refraining from imposing mask mandates, he said the benefits of N95s and other high-filtration masks are more pronounced.

When people says what’s the point of pushing #BetterMasks when many people don’t wear any mask at all… I say— that is one of the points. Less masking, more infectious aerosol in indoor spaces, more bang for the buck from a better mask.

And with under-staffed hospitals struggling to handle the COVID-19 surge, he suggested widespread adoption of such masks would be a way to blunt omicron transmission without imposing the “circuit breaker” shutdowns others have suggested.

Although the majority of the population is vaccinated and early evidence suggests omicron causes milder illness, Karan wrote that the small percentage of hospitalizations from a massive number of infections could end up being a large burden for the health care system.

Better masks, he wrote, could be a quick fix.

“In a viral surge, time is everything, [especially] with exponential spread,” Karan wrote. “It means you cannot reasonably vaccinate your way out. You cannot depend on test results that take days to come back. You cannot hedge on quarantining or isolating. You cannot wait to start using better masks.”

2/ You essentially need a way to stun transmission. Many have called for circuit breaker events in which any social interaction that could introduce transmission stops altogether outside of households (a “lockdown”) However, I don’t think this is necessary to achieve this.

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