April 9 (UPI) -- Since COVID-19 started spreading in the United States, a debate has raged over whether the public should wear masks -- and until recently, the answer was no.
The U.S. Centers for Disease Control and Prevention, the nation's leading government health agency, now says that wearing a protective mask is recommended for people who need to be in public settings -- including a run to the grocery store -- when "other social distancing measures are difficult to maintain."
The goal, the agency and experts say, is to prevent spread of novel coronavirus by people without symptoms who might not know they have the disease.
The World Health Organization, however, issued guidance this week that seemingly contradicts the CDC, saying that healthy people in the community wearing masks is not supported by current evidence and carries risks, including self-contamination.
"There's definitely confusion and a lot of misunderstanding about these recommendations from the public point of view," Kelly A. Reynolds, professor and chair of community, environment and policy at the Zuckerman College of Public Health at the University of Arizona, told UPI.
Much of the confusion revolves around the purpose of wearing the masks, Reynolds said. Many Americans seems to think that wearing a mask will help keep them from getting sick, which is not the case.
"What the WHO is saying is, 'Wearing a mask won't necessarily protect you from getting the infection, but it will help prevent you from spreading the disease to others if you don't have symptoms and don't know you're sick.' And the CDC is recommending masks to prevent spread of COVID-19," Reynolds said.
"I actually don't think the two are at odds on this issue at all."
Data on the new coronavirus is limited -- the key word being "new" -- but scientific evidence exists supporting the use of face masks to cover the nose and mouth to prevent disease spread when the primary route of transmission is through "aerosols," Reynolds said.
Studies to date have indicated that COVID-19 is spread most often via "respiratory droplets" released when an infected person coughs.
"We don't know how effective wearing a mouth and nose covering like a bandana or mask is for COVID-19, but it has what we call 'biological plausibility,'" Dr. Mark Dworkin, professor of epidemiology at the University of Illinois at Chicago School of Public Health, told UPI.
"That means that it makes sense if you were blocking a COVID-carrying droplet immediately in front of someone's face. We do this for well people all the time when we mask up a surgeon before they do a surgery," Dworkin said.
One argument against the use of face masks by the public has been the limited supply of "healthcare-grade" N95 coverings available. Most experts -- including those at the CDC and WHO -- agree that these masks should be reserved for front-line healthcare workers, which is why the CDC has been advocating for use of homemade masks "like a bandana," Dworkin said.
"The bottom line is still about washing your hands, avoiding touching your eyes, nose, and mouth with unwashed hands, social distancing and isolation," he added.
Reynolds agreed, saying that "if you're worried about getting the virus yourself, which all of us are, the best thing to do is stay home. That's always going to be your first line of defense."