Do Masks Really Help Reduce Transmission of COVID-19?

We are at War with Eurasia, We have always been at War with Eastasia

In his novel, 1984, George Orwell coined a new term, “doublethink.”  Doublethink was a word that described the ability and willingness of an individual to hold two contradictory ideas at the same time, and fully believe both of them.  The federal government’s flip-flop on the ability of face masks to stem the transmission of coronavirus seems to be another example of doublethink.  Before April 4, 2020, the federal government suggested the general public not wear face masks, except in very specific circumstances.  Many communities followed the CDC’s lead and suggested the public avoid wearing face masks in public.

Yet, suddenly, the CDC changed its guidance in early April.  All of the sudden, they encouraged the general public to wear face masks in public.  Communities, who a day or two earlier were issuing recommendations against face masks, suddenly changed direction with little explanation, and recommended the public wear face masks.  Some jurisdictions even started issuing fines for people who failed to wear masks in public areas.

Why were the recommendations about masks changed so abruptly, and why were local communities so willing to unquestionably follow the new guidance when they were religiously following other guidance just a day or two earlier?

The Flip Flop

About April 4, the Centers for Disease Control and Prevention (CDC) abruptly changed their position on the public wearing masks to prevent coronavirus.  Before this date, the CDC agreed with the World Health Organization’s (WHO) guidance that masks should be reserved for healthcare workers, and masks for the rest of the population should be limited to people caring for persons with COVID-19.

The recommendations against the general public wearing masks (which is still WHO’s position) were based upon a need for public manipulation as well as valid concerns about masks.  Due to the coronavirus pandemic, medical-grade respirator masks and surgical masks were in short supply, and the United States government wanted the production of these masks directed solely to healthcare workers.  Because of this desire, the government strongly suggested that masks were not needed by most of the general public.  The federal and state governments wanted the sale of all medical-grade masks limited to healthcare professionals.

That is not to say there weren’t valid, or at least plausible, explanations for discouraging the public from wearing masks.  The ability of masks to protect the wearer or others from the virus is greatly reduced if masks are not properly fitted.  Air gaps will let bioaerosols escape or enter.  The outside surface of masks tend to collect viral particles, so care must be taken to avoid touching the outer surfaces of masks and to practice good hand hygiene.  In fact, WHO points out, “masks are effective only when used in combination with frequent hand-cleaning with alcohol-based hand rub or soap and water.”    

Considering most lay persons would not fit their masks properly, studies show the outer surface of a mask collects viral particles, and most people would not handle masks properly, the discouragement of masks appeared to make sense.  On top of this, the ability of homemade masks to filter out bioaerosols was not widely studied.

Despite the recommendations of the United States Surgeon General and the CDC, many people started ignoring the guidelines, and chose to wear masks out in public anyway.

It would not be implausible to believe the federal government changed direction on masks due to public pressure, rather than medical consensus.  Ostensibly, the government “discovered” the coronavirus can be transmitted by asymptomatic or pre-symptomatic carriers.  On the April 5, 2020 broadcast of Meet the Press, Surgeon General Jerome Adams said, “Here’s what’s changed.  We now know that about 25%, in some studies even more, of COVID-19 is transmitted when you are asymptomatic or presymptomatic.

However, this claim doesn’t fully explain the reason for the sudden shift in guidance.  It was suspected since January, and widely accepted by early March, that a significant quantity of coronavirus infections was asymptomatic.  If asymptomatic transmission was such a true concern, wouldn’t the CDC have changed its guidance at least a month earlier than April 4. 2020?  If wearing masks truly prevented asymptomatic carriers from transmitting COVID-19, didn’t this delay potentially contribute to increased infections?

We can only speculate on the reasoning for the CDC’s change in policy.  It is very possible they were confident that medical-grade masks were finally making their way to healthcare workers in early April, so there was no longer a concern of the public trying to hoard them.  It is also well within the realm of possibility the CDC still doesn’t see a true need for the general public to wear masks, but they changed direction due to political pressure.  It is rapidly becoming more and more obvious that governmental regulations are being driven by the public’s demand that the government “do something,” even if these policies have no actual impact on the progression of COVID-19.  The change in guidance regarding masks may have simply been the desire to create more political theater to placate a fearful and panicked population.

In light of the new guidance from the CDC, and in spite of WHO’s contention the general public generally does not need masks, many municipalities have mandated the wearing of masks for anyone out in public.  Some are even levying fines against those who defy the edict.

How Effective are Masks Really?

In light of the rapid about-face on the guidance about wearing masks, it is fair to ask whether they really make much of a difference in preventing the spread of coronavirus or in protecting the wearer from catching the infection.

There is fairly widespread consensus that N95, P95, and R95 respirators, when properly fitted, prevent 95% + of viral bioaerosols from entering the mask or leaving the mask.  However, x95-class respirators are not currently being sold to the general public.  Some people may have previously purchased respirators meeting this standard and still have them at their homes.  Provided an x95 mask is fitted without air gaps, not used beyond its recommended lifespan (usually four hours for disposable masks), and handled properly, these masks provide substantial, but not perfect, protection from catching or transmitting coronavirus.

Pleated surgical masks are still being directed to health-care facilities, although some may occasionally be available for purchase by the general public.  Studies don’t entirely agree on how effective surgical masks are at filtering the bioaerosols containing the COVID-19 virus.  A South Korean study published in the Annals of Internal Medicine suggested that surgical and cloth masks provide no protection against coronavirus bioaerosols. However, another study, published in Nature Medicine, found that surgical masks were an effective method of blocking viral bioaerosols.  A third study, in BMJ Open, suggested that surgical masks provide about 56% protection from bioaerosol infiltration or transmission.

There is not universal consensus on the effectiveness of non-woven surgical masks in providing protection from receiving or transmitting coronavirus bioaerosols.  Surgical masks are certainly less effective than x95 respirators.  But they do appear to provide some protection from COVID-19 penetration, provided they are worn over the nose and mouth with no air gaps.  As is the case with other masks, surgical masks should be carefully handled after use and touching the surfaces, especially the outer surface, should be avoided.  The user should always wash his or her hands immediately after removing any mask.

Since x95 respirators and nonwoven surgical masks are hard to come by, most of the public is relying upon home-made masks or bandanas.  What impact do these devices have?

Depending upon the build and demeanor of the wearer, a bandana can make him look sort of like a cowboy.  A cotton mask can make one appear to be a second-rate bank robber. Generally, these homemade contraptions offer very limited protection from dispersing or receiving coronavirus bioaerosols.  The BMJ Open study claims 97% or bioaerosols can penetrate cloth masks.  In fact, the study’s authors conclude, “Moisture retention, reuse of cloth masks and poor filtration may result in increased risk of infection.”  In essence, cloth masks may increase, rather than decrease, the risk of coronavirus infection.

A study in the American Chemical Society’s journal, ACS Nano, provided more positive data for the effectiveness of homemade cloth masks.  This study examined different fabrics, with different thread counts, and the impact of single-layer masks versus multi-layer.  The study still did not provide good news about the filtration ability of typical single-ply cotton masks.  The study found 80 threads-per-inch single-ply cotton masks filtered about 9% of airborne particles of the size most typical of coronavirus.  Some other materials and thicknesses fared much better, with cotton/chiffon, cotton/silk, and cotton/flannel blends performing about as well as x95 respirators, provided the masks were fitted properly with no air gaps.  If these masks did have air gaps, which is rather typical in home-made masks, the filtering efficiency dropped to below 40%.

It’s probably fair to surmise that home-made masks with multiple layers of fabric (particularly non-woven fabric) and higher thread counts offer more protection from viral infiltration than typical, single-ply cotton masks.  However, when fabric weaves are tighter and multiple layers are used, it may be far more difficult actually breathing through one of these masks.  Wearers may be inclined to lift the mask occasionally to breathe, which negates any benefits of wearing a mask.

Are Masks Desirable?

There has been considerable debate as to whether face masks are necessary, or even desirable, for non-medical personnel.  First, we have to consider the real threat of one person infecting another through aerosol transmission of COVID-19.  The previously referenced study published in Nature Medicine suggests that people infected with viruses like coronavirus seldom shed detectable amounts of the virus in respiratory droplets or aerosols, and those who do shed the virus through bioaerosols tend to have very low viral loads.  The authors of the study believe this finding implies, in order to be infected by respiratory aerosols or droplets, a person must be in prolonged contact with an infected individual.  Fleeting contacts would not usually be sufficient to transmit COVID-19 through bioaerosols.

This is admittedly only a single study.  Not a lot is yet known about the transmission of the coronavirus, and whether it is primarily transmitted through the air or by surface contact. 

We must also address the limitations of the studies referenced above.  Most of the studies measured the transmission of potential viral loads from areas fairly close to the mask (usually one meter or less).  The studies did not measure the viral load of respiratory droplets or aerosols that travel longer distances, such as from a cough or sneeze.  No studies have evaluated how effectively different types of masks limit the distance droplets or aerosols can be projected.  If, in spite of the study published in Nature Medicine, casual encounters with aerosols or droplets can cause infection, a mask’s ability to suppress the travel distance of viral particles would be desirable.

In general, it is fair to say x95 respirators and surgical masks will likely provide some protection from catching or transmitting coronavirus, provided the masks are fitted properly, remain dry, are handled carefully when being removed, and are not worn longer than the manufacturer’s recommendation.

There is not as much certainty of the value of home-made masks.  The most common materials found in home-made masks and facial coverings only filter miniscule proportions of droplets and aerosols.  Common single-ply cotton masks, when properly worn, filter out 9% or less of bioaerosols.  These masks may or may not reduce the distance such bioaerosols travel from a cough or sneeze, but it appears unlikely that makes any difference in actual infection potential.

There is a psychological value in wearing home-made masks.  One may feel virtuous that he or she is protecting others from potential exposure to viral particles (although such a belief is likely incorrect).  A mask can also be perceived as equivalent to suit of armor – protecting the wearer in public.  Unfortunately, this belief can be dangerous if it gives the wearer a false sense of security that encourages one to drop his or her guard.  If a person believes a mask offers protection to oneself or others, the wearer may be less inclined to engage in social distancing or frequent hand-washing, both of which are considered more effective at limiting the transmission and catching of the virus than wearing a mask.

Home-made masks may actually be more dangerous than not wearing a mask at all.  It has already been established that most commonly used home-made masks have a very limited ability to filter viral particles.  If the concerns of the authors of the BMJ Open study are correct, improper handling of masks (remember, viral particles often collect on the outside surface of masks), moisture retention, and improper fitting (the presence of air gaps or a failure to cover the mouth and nose) can increase, rather than decrease the risk of infection or transmission of disease to another.

These conclusions appear to be counter-intuitive and contradict common sense.  One may argue that even a little bit of protection from viral infiltration is desirable.  It would be, provided a mask is always carefully handled, washed frequently or correctly disposed-of after use, fitted and worn properly, and if the wearer complied with all other social distancing and personal hygiene guidelines.  In the real world, however, people are not likely to perfectly follow all of the guidelines.  Researchers have recommended that health-care workers wear home-made masks only as a “last-resort.”  The use of the same masks by untrained individuals appear to provide very little benefit in filtering bioaerosols, and may actually increase, rather than decrease the rate of infection.

The abrupt about-face of the CDC in changing their policy on public use of face-masks looked suspiciously like it was caused by political pressure, rather than comprehensive medical research.  In spite of the most recent direction from the CDC, the position of WHO on the public use of face masks seems more in sync with current medical research.

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