Masked and unmasked

 

News analysis

A Danish study of masking branded as “controversial” long before it saw the light of day finally emerged in print on Wednesday only to add to the confusion over whether ordering people to wear face coverings to prevent COVID-19 is a good thing or a bad thing.

Anti-maskers in the U.S. are sure to latch onto the peer-reviewed study published in the Annals of Internal Medicine as evidence that mandatory masking is just another unnecessary government intrusion into the lives of freedom-loving Americans.

Pro-maskers, meanwhile, will argue the study presents no evidence that masks don’t work to slow the spread of the sometimes deadly disease and note that the authors say they’re not opposed to public masking.

Eight months into the worst pandemic in the Digital Age, what the study mainly reveals is the failure of science to quantify exactly how the newly evolved SARS-CoV-2 virus jumps from person to person.

As the study’s authors observe, “how SARS-CoV-2 is transmitted – via respiratory droplets, aerosols, or (to a lesser extent) fomites – is not firmly established. Droplets are larger and rapidly fall to the ground, whereas aerosols are smaller (less than 5 μm) and may evaporate and remain in the air for hours.

“Transmission of SARS-CoV-2 may take place through multiple routes. It has been argued that for the primary route of SARS-CoV-2 spread – that is, via droplets – face masks would be considered effective, whereas masks would not be effective against spread via aerosols, which might penetrate or circumnavigate a face mask. Thus, (the) spread of SARS-CoV-2 via aerosols would at least partially explain the present findings.

“Lack of eye protection may also have been of importance, and use of face shields also covering the eyes (rather than face masks only) has been advocated to halt the conjunctival route of transmission. We observed no statistically significant interaction between wearers and non-wearers of eyeglasses. Recent reports indicate that transmission of SARS-CoV-2 via fomites is unusual, but masks may alter behavior and potentially affect fomite transmission.”

Fomites are objects – doorknobs, elevator buttons and gas pump handles, for example – to which invisible, microscopic virions carried by an infected person can temporarily attach themselves to await contact with a potential new host.

Dashed hopes

One of a handful of masking studies undertaken since the pandemic began near the start of the year, the randomized controlled trial (RCT) involving almost 5,000 Danes was expected help clarify the effectiveness of public masking – one of several so-called “non-pharmaceutical interventions (NPIs) being used in attempts to slow the spread of a virus that has led to nearly 1.4 million deaths around the world – almost 260,000 of them in the U.S.

Back in July, researchers at the Centre for Evidence-Based Medicine at the University of Oxford noted the problematic lack of studies on public masking.

“In 2010, at the end of the last influenza pandemic, there were six published randomized controlled trials with 4,147 participants focusing on the benefits of different types of masks,” wrote researchers Tom Jefferson and Carl Heneghan. “The face mask trials for influenza-like illness (ILI) reported poor compliance, rarely reported harms and revealed the pressing need for future trials.

“Despite the clear requirement to carry out further large, pragmatic trials a decade later, only six had been published….and showed that masks alone have no significant effect in interrupting the spread of ILI or influenza in the general population, nor in healthcare workers.

“It would appear that despite two decades of pandemic preparedness, there is considerable uncertainty as to the value of wearing masks….The numerous systematic reviews that have been recently published all include the same evidence base so unsurprisingly broadly reach the same conclusions,” they wrote. “However, recent reviews using lower quality evidence found masks to be effective. Whilst also recommending robust randomized trials to inform the evidence for these interventions.”

The Danish study was one of those randomized trials – the gold standard of medical research – intended to inform the debate. It has mainly just added to the grays surrounding the discussion.

The study found no statistical difference in infection between the number of infected people who wore masks and those who didn’t. But the authors warned that “the findings…should not be used to conclude that a recommendation for everyone to wear masks in the community would not be effective in reducing SARS-CoV-2 infections because the trial did not test the role of masks in source control of SARS-CoV-2 infection.

“During the study period, authorities did not recommend face mask use outside hospital settings and mask use was rare in community settings. This means that study participants’ exposure was overwhelmingly to persons not wearing masks.”

In other words, the study concluded that masks provide no protection for the wearer – although the U.S. Centers for Disease Control (CDC) recently declared the opposite – but provided no real data on whether a mask wearer’s face covering helps to protect others.

Masking has become highly politicized, and the possibility that it could help slow the spread of a disease for which there are few other good preventative measures has made most scientists reluctant to say anything negative about masks.

Michael Osterholm, the director of the respected Center for Infectious Disease Research and Policy (CIDRAP) at the University of Minnesota, actually found himself attacked by other scientists for offering a nuanced view that argued stopping the spread of SARS-CoV-2 required more than people just slapping on masks. 

Never say never

After studying a variety of NPIs – including masking – in 41 countries between January and the end of May, an international team of researchers from Oxford, Harvard University, the Australian National University, the University of Bristol, the University of Manchester, Tufts Univesity and the Imperial College of London observed that although their “results cast doubt on reports that mask wearing is the main determinant shaping a country’s epidemic, the policy still seems promising given all available evidence, due to its comparatively low economic and social costs. Its effectiveness may have increased as other NPIs have been lifted and public interactions have recommenced.”

The study itself concluded mandatory masking had a minor negative effect, but the score of a negative 1 percent determined by the study was within a range of a minus 13 percent to a positive 8 percent, offering at least the possibility masking could be a plus.

The study was posted at MedRxiv and was not peer-reviewed. It has received almost no publicity although it offered government entities a calculator for determining how various NPIs could be used to slow the spread of the disease. 

The study found the most effective NPIs were closing schools and universities, limiting gatherings to 10 people or less, and closing most non-essential businesses. Those also happen to be the most unpopular and/or economically devasting NPIs.

The wild card in the debate on how well NPIs do or don’t work focuses on how the disease spreads, and that has had scientists taking sides.

“Many scientists now consider that COVID-19 spreads through aerosols, containing particles of diameter 5 μm or less, with extended viral survival in the air as well as long periods of suspension of the microdroplets in the air. (But) respiratory droplets are still considered to be the main route of transmission,” Dr. Liji Thomas wrote at News Medical in September. 

Little has changed since then except for people in cooler climates moving increasingly indoors and the number of COVID-19 infections exploding.

An international team of researchers from Georgia, Louisiana and California reported on the danger of closed environments in a peer-reviewed study published on the JAMA Network in September.

Their study tracked a COVID-19 outbreak in China back to Buddhists on a bus. The study reported 23 of 68 people who traveled in a bus with someone infected with SARS-CoV-2 came down with the disease, but only seven of another 231 people with whom the infected individual had contact at a religious retreat caught the disease.

“…None of the passengers sitting in seats close to the bus window developed infection,” the study added. “In addition, the driver and passengers sitting close to the bus door also did not develop infection….Our findings suggesting airborne transmission of COVID-19 align with past reports of a severe acute respiratory syndrome outbreak on a plane and a recent COVID-19 outbreak in a restaurant.”

The protective value of fresh air in the face of an infectious, airborne pandemic disease has been known since the Spanish flu killed an estimated 675,000 Americans and millions around the globe more than 100 years ago. 

Masks were then the subject of much the same debate as they are now.

Mechanics

Rogue epidemiologist Anders Tegnell of Sweden has suggested masks could actually be dangerous.

As outrageous as that claim might sound to some, it is not farfetched. Masks are a tool. Like other tools – knives, chainsaws, motor vehicles – they are useful when used properly but can become dangerous, even deadly, when used improperly.

In a health-care environment, masks are one element in an outfit of personal protective equipment (PPE). There are protocols for how PPE is used in that environment.

Masks in the public arena are not treated like PPE. They are now regularly treated like a fashion accessory to be used when entering public spaces.

In between, they hang off the mirrors of automobiles, get stuffed in pockets, and are handled countless times by their owners. If someone is infected with COVID-19, her or his mask is likely to end up with SARS-CoV-2 all over it.

What happens to these virions when someone then puts on the mask and start pushing air out through it is an unknown. Fancy photography has caught the outpouring of droplets when humans breathe, but individual particles of SARS-CoV-2 are so small they can’t be caught on film.

A team of scientists from Israel, California and Massachusetts this week estimated that “each infected person carries 10⁹-10¹¹ virions during peak infection, with a total mass of about 1 µg-0.1 mg, which curiously implies that all SARS-CoV-2 virions currently in the world have a mass of only 0.1 to 1 kilogram.”

A kilogram, for those unfamiliar with the metric system, equals 2.2 pounds. There are now 16 million people reported to be infected with SARS-CoV-2, meaning that each of them would be carrying at most about 0.0000001375 of a pound of virus or 0.0000022 ounces.

It is not like scientists can put a fancy lens on a camera and track these virions as they fly around a room when COVID-infected individuals breathe.

Not to mention that masks themselves are only part of the equation. The human element also plays a big role.

”…The wearer of a face mask may change to a less cautious behavior because of a false sense of security, as pointed out by WHO,” the Danish researchers warned. “Accordingly, our face mask group seemed less worried, which may explain their increased willingness to wear face masks in the future. These challenges, including costs and availability, may reduce the efficacy of face masks to prevent SARS-CoV-2 infection.”

The research here is caught at the crux between science and belief, and a lot of people now believe in masks because there are no good alternatives other than shutting down entire societies which doesn’t work because economies collapse and the whole faces a greater risk than the comparative few dying from latest disease to inflict humankind.

Though the 252,262 Americans killed by COVID-19 since March is a sad and frightening number, it is significantly smaller than the 424,000 Americans who would normally be expected to die of heart disease over an eight-month span or the 399,000 who would normally die of cancer in eight-months.

Still, no one wants to die, and there has been no demonstration that masks make things worse, as the Danish scientists noted.

“While we await additional data to inform mask recommendations, communities must balance the seriousness of COVID-19, uncertainty about the degree of source control and protective effect, and the absence of data suggesting serious adverse effects of masks,” they wrote.

But then no one has really gone looking for serious adverse effects although a study of Saudi Arabian women in the late 1990s found that the 58 percent who wore veils were “significantly more” likely to suffer from asthma or respiratory infections.

Reporting in the Journal of Asthma, the researchers termed the finding unexpected and said “more  and bigger studies are recommended.” But, as with the studies of flu and masking a decade later, no further research was conducted.