If practically everyone in America wears masks while out in public, it could prevent tens of thousands of Covid-19 infections and deaths by the fall, according to researchers at the University of Washington's Institute for Health Metrics and Evaluation (IHME).
"It is hard to imagine any health intervention that would be more cost-effective," Theo Vos, professor of health metrics sciences at the IHME, tells CNBC Make It. "Even if causing a small amount of discomfort to everyone."
Currently, with mask use as it is (between 20% and 60%, according to IHME) the model predicts over 208,200 cumulative deaths by Nov. 1. The model also predicts predicts over 100,000 infections a day by late September, topping out at nearly 168,000 projected new infections on a single day on Nov. 1.
To date, there have been at least 3 million infections and 132,000 Covid-19 deaths in the United States, according to data from Johns Hopkins University and Medicine. The U.S. hit a record single-day Covid-19 infections on July 8, with 60,000 daily infections reported.
But that could all change if 95% of people now start wearing masks anytime they're in public, according to the model. Universal mask usage could prevent nearly 45,500 projected Covid-19-related deaths by Nov. 1, or about a 58% reduction, Vos says.
"In the mask scenario, assuming we can get 95% of people to always wear a mask, the cumulative deaths will reach 162,808 [by Nov. 1]," Vos says.
As for infections, the model predicts that universal mask usage could reduce the number of infections on Nov. 1 to a little under 33,500, an 80% reduction.
This is "quite a big difference," Vos says.
So what does this mean for you? Wear a mask whenever you mingle with people, Vos says. Masks and cloth face coverings create a barrier to keep your respiratory droplets from spreading to other people and potentially infecting them, according to the Centers for Disease Control.
A recent Gallup poll suggests that while mask usage among Americans is becoming more common — the percentage of U.S. adults who said they had worn a mask in public in the previous seven days went from 51% in early April to 86% in late June — not everyone is on board: 11% of US adults surveyed in June said they have not considered wearing a mask.
Dr. Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases, said that he's "strongly in favor of" mandating the use of face masks because of their efficacy.
This most recent IHME projection has not yet been peer-reviewed, but Vos says the results have been shared with the CDC and a group of modelers, convened by the World Health Organization, for comparisons. The IHME will submit a number of papers on the model at the end of this week, he says.
But the findings track with other studies on masks and their effect on Covid-19.
A model from the University of Cambridge found that if 100% of people wore masks all the time in public, it could prevent a second wave of Covid-19 in the 18 months that it will likely take to get a vaccine to market. (The United States is still experiencing the first wave of Covid-19; the second one would occur when the virus returns or when a new strain of the virus develops.)
"As we all have come to recognize, wearing masks can substantially reduce transmission of the virus," IHME director Dr. Christopher Murray said in a press release. "Mask mandates delay the need for re-imposing closures of businesses and have huge economic benefits. Moreover, those who refuse masks are putting their lives, their families, their friends, and their communities at risk."