In 2020, chief medical adviser to the president Dr. Anthony Fauci was usually wearing a cloth mask. Last winter, he often switched to a multi-layer surgical mask.
"A double ply mask would be good," he said.
This winter — an N95 respirator.
COVID has been evolving. So too, the recommendation of top health officials, like Fauci.
"We should be wearing the best possible mask that we can get," he said.
And by that, he was referring to N95-type masks, which have an electrostatic layer that captures the most minute particles.
Why the mask migration?
Since the start of the pandemic, masks of all sorts have been tested. And, by last spring, a widely respected study reported that cloth masks can leak 75% in and out. Surgical masks only leak 50%, and N95 respirator masks as low as 1% to 10%, if correctly fitted.
Amid Omicron setting new infection records the CDC, last week, updated its guidance to specify that "properly fitted respirators provide the highest level of protection."
Dr. Ashley Styczynski, an infectious diseases specialist at Stanford, studies mask efficacy.
"Now, this time, we're seeing this really transmissible variant that we need to roll out the big guns," she said.
NEWSY'S JASON BELLINI: Did we know from the beginning that you'd be a lot better off if you had an N95 for your protection?
ASHLEY STYCZYNSKI: We were thinking that the main route of transmission was through droplet particles and droplets are much, much bigger than aerosols. And so a cloth mask would probably work equally as well as N95 when it comes to filtering out those large droplet particles. But I think this is where our thinking has evolved as we've learned more about it and realized that this virus can actually be transmitted through aerosols through airborne transmission. These are much smaller particles that can easily get through some of these cloth masks.
Through and also around. Around any mask, in fact, if it's not sealed well to the face. And that's where differences emerge between the different types of respirator masks, as demonstrated by the self-proclaimed "mask nerd" Aaron Collins. He's an engineer who tests and reviews masks.
His experiments find that N95s, which are strapped to your head with a headband, provide the snuggest fit and best protection. But not everyone finds them comfortable to wear for long periods.
KF94s and KN95s use ear loops, which don't seal quite as well. That's the tradeoff.
KF94s are the South Korean JJJ. Standard. Widely respected. Performing nearly, but not quite as well as the N95s in Collins' tests.
KN95s are the Chinese version. And some experts question the consistency of their quality and note there are a lot of fake KN95s out there.
Many factors to consider now that health authorities advise that wearing higher-quaility masks can make a considerable difference.