The Centers for Disease Control and Prevention has updated its mask guidance to note that N95 and KN95 masks offer higher levels of protection againstthan cloth masks, although it stopped short of recommending that everyone wear them. The change comes as the rapidly-spreading continues to cause record-breaking numbers of infections, straining the ability of hospitals to treat the influx of patients.
"Well-fitting NIOSH-approved respirators (including N95s) offer the highest level of protection," the CDC's website now says, referring to products evaluated by the National Institute for Occupational Safety and Health.
The CDC says loosely woven cloth masks provide the least protection, while those with layers, well-fitting disposable surgical masks or KN95 masks offer progressively more.
"It is important to remember that any mask is better than no mask," the agency says, encouraging people to choose one that fits well and that they can wear consistently.
N95 masks have been the gold standard of protection since the beginning of the pandemic, and should filter 95% of airborne particles. Those labeled "surgical" should be reserved for health care workers, but basic disposable N95 masks are available online and are no longer in short supply. N95 masks approved by NIOSH are marked on the filter.
The CDC's website offers tips on how to detect counterfeit N95 masks. Some of the signs that you've purchased a box of include the lack of markings on the mask, the absence of an approval number, the misspelling of NIOSH, the use of ear loops instead of bands that go around the head, and claims that the mask is approved for .
KN95 masks, which are the Chinese standard and are also required to filter out 95% of particles, also meet international standards but are not regulated by the U.S. However, the CDC warns that about 60% of the KN95 masks sold in the U.S. are fake and don't meet NIOSH standards for filtration.
Masks labeled KF94, from South Korea, offer a similar level of protection, filtering 94% of airborne particles.
Many public health experts have been urging Americans to upgrade to better masks, especially in recent weeks as.
"Cloth masks aren't going to provide a lot of protection, that's the bottom line," former FDA director Dr. Scott Gottliebon January 2. "This is an airborne illness. We now understand that, and a cloth mask is not going to protect you from a virus that spreads through airborne transmission. It could protect better through droplet transmission, something like the flu, but not something like this coronavirus."
The CDC recommends that anyone over 2 years of age who is unvaccinated and those with compromised immune systems should wear a mask in indoor public places. The agency also says people who are fully vaccinated should wear masks if they're in areas with substantial or high levels of COVID-19 transmission — which right now is 99% of counties in the United States.
Mask wearing is required on public transportation, including planes, buses and trains, and in indoor transportation hubs, like airports and train stations.
Dr. Amesh Adjala, an infectious disease expert and senior scholar at the Johns Hopkins University Bloomberg School of Public Health, told CBS News that mask wearing is crucial because Omicron is so contagious.
"Some of these do-it-yourself cloth masks may not actually be up to the task," he said. "But the most important thing to remember is the best mask is the mask you actually wear. So if people get N95s or KN95s and they can't wear them because they're uncomfortable, or they don't know how to wear them properly, they're not going to be very effective. So the key message is, the mask that you wear religiously, that's the one that's actually going to be the most effective."
In general, the CDC says masks don't need to be worn outdoors, but it says it is worth considering at crowded outdoor events or when engaging in close-contact activities with people who aren't fully vaccinated.