Cloth masks are not enough: Delta’s aerosols are 100 times more infectious than other variants

If you’re vaccinated and considering ditching your face mask, you might want to keep reading.

New data published in the journal Clinical Infectious Diseases suggests that the Delta variant—the most dominant strain in the U.S, is much more transmissible while airborne than previously reported. In fact, the researchers determined that populations who carry the Alpha variant (the dominant coronavirus strain at the time of the study) breathe out 43 to 100 times more infectious viral aerosols than those infected with the original strain of the coronavirus.

And the Delta strain is 60% more transmissible than the Alpha strain.

How much more infectious is the Delta variant?

“The take-home messages from this paper are that the coronavirus can be in your exhaled breath, is getting better at being in your exhaled breath, and using a mask reduces the chance of you breathing it on others,” concludes study co-author Dr. Jennifer German.

German and her team were able to come to this conclusion by measuring how many viral aerosols are expunged from carriers of the virus.

Viral aerosols are particles emitted by a person infected with the novel coronavirus when they talk, breathe, cough, or sneeze. These particles can infect a person who is exposed to them, even if the person emitting them is asymptomatic.

Loose-fitting cloth masks and surgical masks can reduce your risk for airborne infection by roughly 50%, but N95s and K95s are your best bets; so long as they don’t have valves (they make a mask more breathable, but reduce its level of protection in kind).

Most important, the woven material of the majority of cloth masks isn’t as effective at filtering particles as the nonwoven, melt-blown polypropylene that surgical masks and N95s are made of.

Emerging variants and health guidance

The new study was conducted by researchers from the University of Maryland.

More transmissive strains have higher viral loads, which makes them more infectious in every context, including while suspended in the air as aerosols.

“We already knew that virus in saliva and nasal swabs was increased in Alpha variant infections. Viruses from the nose and mouth might be transmitted by sprays of large droplets up close to an infected person. But, our study shows that the virus in exhaled aerosols is increasing even more,” explains co-lead study author and doctoral student Jianyu Lai.

Face coverings dually protect us from viral loads and keep infected people from infecting others. To a point, at least.

Even N95 masks and K95 masks allow some particles to get through. But the more measures standing between you and exposure (face coverings, vaccination, and social distancing), the more you reduce your risk of infection.

The study’s author more broadly recommended that the general public apply tight-fitting masks while establishments work toward improved ventilation, increased filtration, and UV air sanitation.

The best defense against airborne infection

Data recently published in the journal Physics of Fluids identified
N95 and KN95 masks as the best options for crowded indoor events.

Loose-fitting, single-layer cloth masks only filter out roughly 10% of coronavirus aerosols; the other 90% can come through the loose-fitting top of the mask.

Moreover, N95 are designed to fit the face snugly which allows them to filter at least 95% of airborne particulates. Experts contend that cloth masks and surgical masks simply don’t cut it with Delta floating around.

“SARS-CoV-2 is evolving toward more efficient aerosol generation and loose-fitting masks provide significant but only modest source control. Therefore, until vaccination rates are very high, continued layered controls and tight-fitting masks and respirators will be necessary,” the authors of the new report concluded.

Read more about face masks here.