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COVID-19 Update: April 4, 2020 Stopping the virus, the question of masks

By Dr. Arthur Lavin

Glossary

  • Virus– a type of germ that consists solely of a bit of genetic material (DNA or RNA) wrapped in a protein coat.  The coat gets the genes into the target cell where the genes force the cell to make zillions of new viruses, and on it goes.
  • Coronavirus– a species name of a number of different viruses.  Called corona because its protein coat is studded with spike shapes that form a crown, halo, or corona of spikes
  • SARS– CoV-2- the specific name of the new coronavirus
  • COVID-2019- the name of the illness that the new coronavirus is causing
  • Endemic– an illness always present in a region.  One could say strep throat is endemic in the US
  • Epidemic– a sudden burst of an illness that comes and goes over a limited time
  • Pandemic– an epidemic that bursts across the world not just one region
  • Spreadability– how contagious is the disease, how many people will end up infected
  • Severity– what harm does the disease cause, in terms of  how sick you get and how many it will kill
  • Mask- a mask is a loose-fitting cloth or textile that covers the mouth and nose loosely.  A surgical mask is a mask used in surgery
  • Respirator-  for the purposes of the COVID-19 pandemic and other respiratory illnesses, a respirator is a mask that fits very snugly or tightly to the user’s face.  An N95 mask is a respirator.
  • Personal Protective Equipment (PPE)- PPE are any item that covers any part of the body with the design and intent of keeping viruses in the environment from infecting the wearer of the PPE. PPE’s include all masks (which includes respirators), face shields, eye shields, gloves, gowns.
  • Ventilator- a ventilator is a machine that can force a person unable to breathe to inhale and exhale and control both effectively.  They are sometimes called respirators, but during this pandemic the word respirator is now reserved for reference to a tightly fit mask.

 

The Question of Masks

This Pandemic as a Plague

The pandemic of COVID-19 is sweeping across the globe and across all countries, visiting fearful disease and loss of life wherever it appears.  As a result, many people have thought about the pandemic of COVID-19 as a plague, much like the plagues that have afflicted humanity since we first evolved.

I think this is a fair way to think about this pandemic.  Like all plagues, this pandemic is dangerous, it is costing lives, and could cost millions of lives.  It seems to have arrived from nowhere, for no reason, having nothing to do with anything anyone we know has done.  It seems to strike randomly, unpredictably.  With the exception of children, the pandemic threatens everyone.  Older people are in more danger, but young adults also face possibly serious harm.

Like the plagues of old, this pandemic also leaves us all feeling helpless.  Everyone knows, at least right now, that if anyone we care for comes down with COVID-19, there is no drug that will cure it, and treatments available simply keep people comfortable if mildly infected, and supported if more severely infected, while everyone awaits one’s own body to heal.

So one is left feeling, this is a real plague.  It spreads, it can harm, there is little control over stopping it.

And so, as with every plague in human history, we work hard to find some way, some path forward, that offers each of us and all we care for, even a bit of help in protecting ourselves from this virus.

Stopping a Virus

As we all know too well by now, viruses are hard to stop.  Any painting of a plague scene from the past shows people walking around with scarves, turning their heads away from everyone else.  The idea of stopping the movement of a germ onto oneself is not new.

But not many will know how very little we know about how a virus actually manages to get from an infected person all the way over and into an uninfected person.  We know they do, and do it very, very well, but we aren’t sure exactly how.

Two major types of human viruses have attracted our attention in studying how viruses, and really all germs, move around.  The first are the stomach flu germs.  All stomach flu germs, including noraviruses (cruise ship stomach flus), enteroviruses (summer stomach flus), cholera, etc., infect the gut.  And we know, when you have a stomach flu sort of infection, your poop is loaded with the germ causing your case.  Now, here is a rough fact to swallow (literally), but all stomach flus get from one person to another by the germ getting on the hand from the sick person’s poop, usually after wiping (sorry), and then that hand connecting to another person who puts their hand in their mouth (really sorry).

But enough of that example, when we think about the other great branch of infections, all the respiratory infections, we are now clearly talking about the sort of infection that COVID-19 is.  But for all respiratory viruses, it is very hard to pin down exactly how they get from the infected person all the way over to the uninfected person.

It’s a very big question.  In the last great respiratory pandemic the world has suffered, the virus killed more Americans in World War I, than our biggest battle.  The H1N1 pandemic flu virus of 1918 killed about 45,000 American soldiers, and in the biggest battle for Americans in WWI, 26,277 Americans died.  So armies wanted to know how viruses spread.  England went so far as to create the Common Cold Unit in Salisbury from 1946-1989, to find out how colds spread.  They would inoculate surfaces, tissues, hands, nostrils, and measure spread.

And even after all that we don’t have complete answers to these simple questions:

Can a respiratory virus infect a person by:

  1. Traveling in the air all on its own? (Naked virus)
  2. Travel in the air in a large droplet of mucus or saliva or other substance?  (Droplet)
  3. Travel in the air is a fine particle?  (Aerosol)
  4. Sit on a surface and wait for someone to touch it
  5. Moving in the air onto the next person’s airway
  6. Moving in the air onto the next person’s clothing
  7. Landing on someone’s body (not airway) and which part would lead to infection or not lead to infection (hand, arm, face, leg)

One might also like to know:

  1. How many live viruses are emitted by the infected person?
  2. How many live viruses need to get into an uninfected person to make it likely they will be infected?

No worries, we will not be answering any of these questions with regard to SARS-CoV-2, the virus that causes COVID-19, here at this time.  And that is for a very important reason, no one knows the answer to any of these questions when it comes to COVID-19.

Droplets and Aerosols

Before we get to masks, it is important to understand two words:  Droplet and Aerosol

Imagine you are in a brightly lit room, and you are facing forward.  To your side is a black wall that is directly illuminated.

Now, you happen to sneeze, you can imagine all sorts of little dots of light reflecting off all manner of material that your sneeze (or cough) spews out into the air.

Science has distinguished between two types of material in that cloud of stuff:  Droplets and Aerosols

Some studies define any collection of particles small enough to hang in the air for any amount of time an aerosol, but during this pandemic, the term droplet refers to larger particles and aerosol to smaller ones.

Droplets

If droplets are the larger particles, what size are they?  The usual practice is to say a droplet has to be a drop of something larger than 5 micrometers (um) across.  That is the width of the average spider web strand.  A drop of water in a cloud or fog is about 10 um across and that’s how thick a piece of saran wrap is, too.

Droplets 5 um or bigger don’t hang in the air long.

But we spew out quite a number of them.  Sneezing explodes the most droplets, about 40,000 in each sneeze, each moving about 225 miles per hour!

A cough ejects only about 3,000 droplets.  Surprisingly if someone you like talks for 5 minutes, just talking will eject about 3,000 droplets every 5 minutes.

And what is in these droplets?  Many things.  The fluid in a droplet is usually either mucus or saliva.  In the fluid can be cells of the lining of the airway, or of the immune system, and if infected, the germs, in our case, the SARS-CoV-2 virus.

Since droplets drop to the floor quickly usually by the time the particles spread 3 feet from someone spewing.  And since we hope not to get viruses on the floor into our bodies, droplets only have a short time to land on the uninfected, and so if you are well, we think you need to be close to someone whose droplets have the SARS-CoV-2 viruses in them to get infected.  But that is so only if droplets landing on surfaces or clothing don’t continue to cause infection.

Aerosols

If the droplets described above are 4 um or smaller, they hang in the air longer.  Worse, any particle, whether alive or not, that is 4 um or smaller can be breathed deep into our lung tissues.  Larger droplets get stuck in the nose and throat, maybe the trachea, but it takes a particle smaller than 5um, 4um or smaller to float deep into the tiny airways and the tiny, tiny air sacs of the lungs.

These small droplets are what is meant by aerosols.

We don’t know much about how the SARS-CoV-2 virus travels, but studies of the influenza virus found that this virus travels better in aerosols than droplets.  One study found someone with influenza virus spewed out about 33 influenza viruses a minute in their droplets, but about 187 influenza viruses a minute in the finer aerosols.

Aerosols weigh much less than droplets, so they hang in the air, and so if a virus can travel in an aerosol, the air around an infected person will be more contagious than if it only travels by droplet.

How to stop the spread of the SARS-CoV-2 virus?

Really, the only proven way today to stop the spread of this virus is to do what we can to make sure no infected person comes near an uninfected person.  Every nation in the world is trying to achieve that.  Some by screening everyone and placing all infected people into separate facilities (Asia), some by testing only those who are sick and placing them in home (Europe and US).

But the question remains, and now here our ancient instincts arise, is there a way, if I happen to stand next to an infected person, to lessen my chances of getting COVID-19, the illness?

Since we really do not know if one can get infected by touching a surface with the virus on it, we don’t know if cleaning surfaces will help, but until we know, we do this.

The same rationale stands behind other practices followed in every nation on the planet right now:

  1. Wash hands frequently, 20-30 seconds at a time.  We do not know if SARS-CoV-2 spreads from hands, but we do know any soap, any rubbing alcohol, will destroy this virus.
  2. Don’t touch your face.  We know the SARS-CoV-2 virus must land on tissue that touches air (throat, trachea, bronchi, lungs) to live and reproduce, to infect.  So if you never touch your face, you remove the possibility of hands with the virus placing the virus in your mouth, the sort of tissue it seeks.
  3. Stay 6 feet away from everyone.  This will stop spread of the virus by droplet, but not aerosol, which can travel longer distances.  Again, we do not know how far the  SARS-CoV-2 can travel in an aerosol, and still cause infection.

And Now, Do Masks Work?

The short answer is, no one knows.

But here is how we think about it.  Remember from above, a mask refers to any device that covers the nose and mouth but still lets you breathe, with the intent of keeping germs out and you safe from contagion.   A type of mask that fits well and snugly to the face, and is called a respirator.  And respirators certified to block 95% of certain sized droplets and aerosols is called an N95 respirator, or N95.  So we are talking about 3 types of masks:

  1. Plain masks- made from cloth at home.
  2. Surgical masks- crafted by a manufacturer
  3. N95 respirators.

Plain Masks

Sadly these are the most open to the flow of viruses in the air.  They are not as snug on the face as well-crafted surgical masks and they let in about 3 times as many viruses as surgical masks.

Surgical Masks

The term surgical mask refers to specifications defined by the US FDA.

It has to be designed to fit well, but not terribly snug.  If you see someone wearing a very fine surgical mask, you will see plenty of gaps on the sides, and on the top and bottom of the mask.

Clearly, if the person wearing a surgical mask breathes air around the mask that air will not be filtered at all, coming in or going out.

But, if you wear one well enough and are careful to have your breath come in and out through the surgical mask, it will block out those droplets mentioned above, remember these are 5um or larger, including visible spatters.

N95 Respirators

N95 stands for something.

The N stands for NIOSH (the National Institute of Occupational Safety and Health) which has to certify an N95 respirator for this mask to be a N95 respirator.

The 95 stands for 95%, and N95 respirator must filter out 95% of airborne particles sized 0.1 to 0.3 um.  If we are talking about particles only 0.1 um across, that would be 50 times smaller than what a surgical mask can filter out.    These masks typically filter out over 99% of the larger particles called droplets above.

N95 respirators must also be able to fit very, very snugly, and are designed to work only if fit very, very snugly.

The Studies on How Well Plain Masks, Surgical Masks, and N95 Respirators Work

The studies are not consistent in their findings, some find they help, some find they do not.

No studies have yet been published on how well they work for the SARS-CoV-2 virus, none.  Completed studies have looked at how they block catching other viruses, such as RSV and influenza, and other cold viruses.

Here is what a sample of the studies have observed

  1. Some studies find that N95 respirators cut the chance of getting infected by a range of respiratory viruses by 50% and keeping droplets (see above) out by 75%
  2. Some studies find that if you compare people with no masks with surgical masks they found both groups were equally likely to get infected- surgical mask did not help
  3. One study of use of N95 respirators in a Toronto ICU cut the chance of getting the SARS infection by 50%, but the numbers studied were small.
  4. A number of studies observing the experience of people in households found no less chance of getting infected with or without masks.

As you can see, the results vary from study to study.  No definitive evidence exists to prove, or disprove that wearing a plain or surgical mask, or even N95 respirator will substantially lower your chance of getting infected with a respiratory virus.  It does appear that the N95 respirator does better than either plain or surgical masks.

Further, it is far from clear if masks and respirators will ever be more protective than staying away from other people.

Clearly, a person staying alone at home with no contact with anyone cannot get COVID-19.  To the degree each of us can get close to that situation, the less likely we  will get infected with COVID-19.

Wearing a mask simply cannot do as well as this strategy.

A mask may help, or may not, the evidence is not clear, although the N95 respirator likely outperforms plain and surgical masks, and surgical masks likely outperform plain masks and scarves.

A practical point- the discussion of masks means very little if there aren’t any available.  Some masks are available, but not many.  And, whatever bit of help masks of any sort provide, that benefit must go to those whose risk of getting infected is greatest, namely, first responders, which include grocers, police, fire fighters, and health care workers.  Certainly if N95 respirators are in short supply, they must first go to hospitals, police, ambulances, and grocery stores.

A danger masks can pose.  If the virus is blocked by any mask, then those viruses will gather on the surface and so when you remove a mask if you touch the surface your hand will get a good hunk of virus.  So if you use a mask, be sure to remove it by the straps, and do not touch the front of the mask.

BOTTOM LINES

  1. Viruses over the last 3 billion years have figured out how to move from the uninfected to the infected, but we still don’t know how each respiratory virus actually does this.
  2.  We know some possible paths, such as by air and touch, and various time frames, but it would be so helpful to know how each disease transmits to know how to stop its spread even when close to the infected.
  3.  The best way not to get COVID-19 is to not be near other people.  The extreme is one person alone, in no contact with anyone, he or she cannot get COVID-19.  As we add people in our life with whom we are in contact, the risk grows.
  4.  Respiratory viruses that travel in the air can do so perhaps in larger droplets and in smaller aerosols.   If only by droplets, which drop to the floor quickly, then standing 6 feet away keeps you from catching the illness.  If by aerosol, these can hang in the air for hours, so distance is not nearly as protective.  We do not know if COVID-19, as noted, spreads by droplet, aerosol, or touch; or if by several, by which proportion.
  5. Which brings us to masks.  The data is inconsistent, but the N95 respirator works better than the surgical mask, which works better than plain masks.

If someone is well, it is far from clear if wearing a mask will keep you from getting COVID-19, but it might reduce your chance.

As long as masks are in short supply, they should all go to first responders first with only unusual exceptions, and that is our current situation.

If and when masks and N95 respirators once again are easily available to all, it makes sense to use them, they might help.  And at the very least, wearing a mask signals to all that you are aware danger is in the air, and you are someone doing all they can to prevent further spread.  It is a sign of community commitment, really of hope.   We have seen this effect in Hong Kong.  When we left there on February 2, everyone in the airport was wearing a mask.  

The COVID-19 pandemic is a plague, we do feel a need, in the absence of a way we can stop this threat, to do something.  A feeling common to all plagues.  Perhaps masks and N95 respirators are our modern version of actions humanity has taken across the ages when threatened by a plague.

Once again we hope we all come through this dangerous time well and safe.

To your health,
Dr. Arthur Lavin

 

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