WASHINGTON - As the United States stares down the barrel of a pandemic death toll of up to 240,000 even in a good scenario, opinion may be shifting in favour of the use of face masks by the general public.

The Centres for Disease Control and Prevention (CDC) has long recommended against the use of face masks by the public, saying that only people who are ill should wear them. Thus, in obvious contrast to most of South-east Asia and East Asia, almost nobody out and about in America wears a mask.

This has resulted in bizarre and racially tinged incidents of Asians in face masks being taunted and attacked. This week in Georgia, a man was arrested after pulling a gun and telling two people wearing masks to stay away from him.

And given that the US' Covid-19 case and mortality rates have rocketed, some are wondering if, apart from the administration's failure to gear up in time to contain the coronavirus, the fact that most of the general public in a leaky lockdown don't wear masks is a factor.

The CDC's guidance has not changed, Dr Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases and easily the real pandemic expert in the White House Coronavirus Task Force, told MSNBC on Tuesday (March 31).

"What is being actively discussed... is given the fact that there is a degree of transmission from asymptomatic individuals who may not know they are infected, we need to at least examine the possibility - as long as we are absolutely certain we won't take these masks away from individuals who need them - of some sort of facial covering," he said.

"It doesn't have to be a classical mask, but something that will prevent them from infecting others. This is actively being looked at."

Earlier on Monday, in an interview with National Public Radio, CDC director Robert Redfield said the agency was taking another look at the data on mask use by the general public.

"I can tell you that the data and this issue of whether it's going to contribute is being aggressively reviewed as we speak," he said.

The question is simple. If a mask protects a healthcare worker dealing with a Covid-19 or any other patient, or a patient from a healthcare worker, why would it not protect any other person wearing it in any other situation in which he may encounter an infected person at close quarters?

The answer is equally simple. It would.

The CDC has confused the public, a nurse who has been working for two weeks with Covid-19 patients in New York City told The Straits Times, asking not to be named.

"As a professional, I'd be wearing it all the time if I was at work, so it doesn't make sense to tell others not to wear one," she said.

Separately, an emergency room doctor in Seattle, also asking not to be named, said: "As far as I'm concerned, everyone going out should have a mask on."

Official guidelines differ from country to country.

In Austria, the authorities this week ordered all supermarket shoppers to don face masks to stem the spread of the virus.

Neighbouring Germany's eastern city of Jena followed suit, instructing people to put on masks when shopping or travelling on public transport.

The Czech Republic has also issued measures requiring its people to wear masks in public.

In China, the authorities strongly encourage the use of masks in public, though the National Health Commission last month said these were not needed in well-ventilated, uncrowded areas. Actual enforcement of the guideline is left up to local governments.

In the US, a key driver of the CDC's guidance was the need to avert a run on masks to ensure their supply in hospitals.

And despite promises by US President Donald Trump days ago of "millions and millions" of face masks in the pipeline, there is still very clearly a shortage.

This is partly because health staff must ensure they are protected in dealing with any patient exhibiting any of a wide range of Covid-19 symptoms, and are thus using personal protection equipment at an exponentially greater rate than normal.

But with infection rates soaring, the CDC's logic is being questioned.

"The big mistake in the US and Europe, in my opinion, is that people aren't wearing masks," Mr George Gao, director-general of the Chinese Centre for Disease Control and Prevention, told Science magazine in an interview on March 27.

"This virus is transmitted by droplets and close contact," he said.

"Droplets play a very important role. You've got to wear a mask because when you speak, there are always droplets coming out of your mouth.

"Many people have asymptomatic or pre-symptomatic infections. If they are wearing face masks, it can prevent droplets that carry the virus from escaping and infecting others."