Feb. 4 (UPI) — Americans should be more concerned about washing their hands than rushing out to buy face masks to reduce the chances of contracting coronavirus, experts say.

The ongoing outbreak of 2019 novel coronavirus, or n-CoV, in China has spread to 23 countries, with 11 confirmed cases in the United States as of Tuesday. More than 20,000 infections and 64 deaths — most of them in China — have been reported, with at least 3,235 new cases confirmed Tuesday.

The Centers for Disease Control and Prevention has advised against buying face masks, partially because of concerns about shortages and also because scientists don’t know how effective they’ll be against the new virus.

Even so, fears linked to the outbreak have created a run on surgical-style face masks at pharmacies across the country. Some stores say they are sold out.

“We’re working with our suppliers to meet customer demand for face masks,” a spokewoman for CVS, the largest pharmacy chain in the United States, told UPI. “This demand may cause shortages at some store locations, and we are resupplying those stores as quickly as possible.”

A spokeswoman for Walgreens said the chain has “been seeing greater demand for certain products, such as face masks and hand sanitizers, in many of our stores. We continually and closely monitor these types of situations to ensure that we have sufficient supply of those products that may be in greater demand to meet the needs of our customers.”

Rachael M. Jones, an associate professor of family and preventive medicine at the University of Utah, told UPI that while face masks can help keep people from breathing in germs — and might protect them against 2019 n-CoV — potential downsides to using them exist.

Most obviously, increased demand for face masks from the public could lead to shortages in supplies for healthcare workers, who are at risk during outbreaks because they often are on the front lines of patient care.

Officials in China have requested donations of medical supplies, including face masks, from the global community, and government leaders caused a stir earlier this week when photos surfaced of them using protective gear intended for healthcare workers.

Similar shortages haven’t been an issue in the United States currently, but Jones said that they have occurred in past outbreaks.

“Since the 2014-2015 Ebola virus disease outbreak, healthcare facilities and healthcare workers have become more experienced with different types of respiratory protection and there have been stockpiles developed for face masks, which can help to reduce the potential for shortages,” Jones said.

CDC officials, in de-emphasizing the need for face masks in the United States for non-healthcare workers, recommend that Americans avoid contact with people who are sick and practice good “hand hygiene.”

Jones said that while masks and respirators can provide protection against the coronavirus, as well as any other respiratory viruses, this assumes they are used correctly. That’s not always the case without training.

For example, non-healthcare workers wearing masks might come in contact with germs when they lift the mask to eat. They also might bot properly adjust the masks to fit their faces. Both practices could render them ineffective, health officials said.

“The only risk associated with wearing respirators is that they increase resistance to breathing, making it more difficult for the wearer to breathe air in and out,” Jones noted. “When respirators and masks are worn for a long period of time, they can become damp from humid exhaled air and sweat, and are uncomfortable to wear.”

“We don’t routinely recommend the use of face masks by the public to prevent respiratory illness,” Nancy Messonnier, director of the CDC’s National Center for Immunization and Respiratory Diseases, said during a press briefing last week. “And we certainly are not recommending that at this time for this new virus.”