A Centers for Disease Control and Prevention (CDC) report that was released in September is gaining attention after being resurfaced by the right-wing news outlet The Federalist for its finding that the majority of coronavirus-infected people examined wore masks.
The study examined 154 case-patients who tested positive for coronavirus and compared them to a comparison group of 160 individuals who were symptomatic but tested negative for the virus.
"In the 14 days before illness onset, 71% of case-patients and 74% of control participants reported always using cloth face coverings or other mask types when in public," the report read.
"In addition, over 14 percent of the case-patients said they 'often' wore a face covering and were still infected with the virus," The Federalist noted.
According to Nature, many studies on mask use include various assumptions that could influence the data, including that people are wearing masks properly and that mask mandates are actually being enforced. In addition, the effects of mask-wearing found in such studies could be influenced by other shifts in society, such as gathering limitations.
Nevertheless, the publication claimed that research thus far supports the notion that wearing a mask can prevent the spread of coronavirus and save lives during the pandemic. For example, Nature pointed to studies that indicate masks can reduce the chances of both catching and transmitting COVID-19, while others suggest that they might reduce infection severity.
However, the publication noted that the data are "messy, disparate and often hastily assembled."
"There are many types of mask, worn in a variety of environments. There are questions about people's willingness to wear them, or wear them properly. Even the question of what kinds of study would provide definitive proof that they work is hard to answer."
Nature also pointed to a preprint study — which has yet to be peer-reviewed — that found that increases in per capita mortality were lower in regions where mask-wearing was either recommended by the government or the societal norm. Another study examined U.S. mask-wearing in April and May and the effects of American state mandates on their usage. Notably, such orders were estimated to curb the growth of coronavirus cases by as much as 2 percent daily, which the researchers suggested could have prevented as many as 450,000 cases.
In an animal study — which was able to control for confounding variables — researchers found that face barriers helped reduce transmission of COVID-19. In particular, only 25 percent of the animals that wore mask material became infected, while almost two-thirds of those that did not, caught the virus.
As of Monday, the CDC continues to recommend the use of masks as a COVID-19 preventative.