A Flying Doctor's Perspective on COVID-19 Virus - March 23, 2020

As a physician and pilot, I've offered many opinions over the last few years in the pages of the AOPA on aviation safety.  Now I get a turn to offer some medical opinions on health safety.  My purpose here is to state my observations, not only on the medical risks we all face with this new virus but on some of the hype, hysteria and rumor that it has fostered. 
Microscopic view of Coronavirus, a pathogen that attacks the respiratory tract. Analysis and test, experimentation. Sars. 3d render

Please note nothing in the following article is meant to take the place of, or supersede, your physician's advice and instructions and is not intended to serve as medical advice, only as my personal take on the current crisis. What follows is strictly based on medical evidence as supported by our current understanding of this virus and largely based on the CDC published information for medical professionals linked here.  My bottom line is pretty simple: all reasonable precautions that apply to every flu season are encouraged and indicated; current reliable medical information indicates that panic, hysteria and fear are not.

The COVID-19 viral pathogen does not appear to be very different from every other flu virus we deal with yearly.  These viruses are minute strands of DNA (more accurately r-RNA or a close relative of a reverse transcriptase RNA) encased in a simple protective covering.  This viral pathogen has probably been in the population of China for many months, if not longer, but was not publicly acknowledged to the rest of the world.  That has affected our response since testing requires knowing the exact nucleic acid sequence of the RNA in order to identify the virus. It has been frustrating and slow to get enough testing kits to identify the virus in our population largely but we have only known the nucleic acid sequence of the virus for a month or so (the first case reported here was on 1/23/20). This fact alone makes many questions unanswerable about this new virus and has left the door open for speculation and conjecture, both of which are understandable but fuel a lot of the current hysteria. 

The infectivity of the virus is a simple ratio of the number of people with the virus divided by the population.  Since testing has been slow to reach all but the most symptomatic patients, we have no way to know how infectious this virus is since we only know about those with symptoms who have been tested but not the actual number among us who are infected (the true numerator of the equation).  As of this afternoon, the CDC can document 33,404 infected Americans. This number WILL go UP as testing becomes more prevalent, but according to current statistics the incidence of this virus in the US population is 0.0000086 or 0.0009%.  Therefore, you have to come into contact with about 100,000 people before you meet 1 person with the virus.  Since every KNOWN infected person in the US is quarantined the chances of meeting a culture positive person is probably less, although as stated above, not known at this time.   BUT the virus is asymptomatic in most cases (Kevin Durant is playing basketball today and announced he cultured positive) so the actual number of folks you have to shake hands with to catch the virus is possibly less than this.  There will be a "rapid rise" in the number of coronavirus cases that will appear "very alarming" on news channels, but this is likely due to increased testing as well as the natural spread of the virus.  Unless sequential testing is done, which of these two factors contribute to the "alarming spread" of the virus will not be known.  The British today released some of the final statistics on the Diamond Princess cruise ship that was essentially a floating agar plate incubator for the virus and it seems that even in those tight spaces 86% of the people on the ship have final test results that are culture negative for the virus.  So it obviously spreads in crowds but many people who are exposed do not seem, at least as of now, to have contracted the illness.

The next obvious and well-founded concern is how deadly is this virus? This is also unknown regardless of what you might hear or read.  To know this information we need to know the number of people who die from this virus divided by the true number of people infected with the pathogen that survive and again, that number is simply unknown. Using current statistics the COVID-19 virus appears to be about as lethal as the H1N1 "swine-flu" of a few years back.  Of the 33,404 known cases, so far 400 patients have died from this virus in the US. That calculates to 1.1% mortality as compared to the swine flu that had a lethality of somewhere between 0.1-2% depending on age group.  The number of deaths WILL increase as the virus spreads but it is most likely that the lethality of this virus WILL go DOWN as we test more people and identify more asymptomatic carriers who do not become sick or die.   Another issue comparing the H1N1 virus to the COVID-19 virus is that a different subpopulation appears to be most at risk.  H1N1 and many other flu viruses we have suffered precipitated a particularly devastating and lethal disease in children (so far this year alone there have been more than 149 pediatric flu deaths) whereas COVID-19 appears to almost spare children (although this is also not known for sure).  The youngest patient to die of the virus in the world known so far was in China and was 15 years old.   It appears to more seriously impacts elderly patients.   The average age of patients here in the US who has died is about 80 years old and 99% had 3 or more concurrent medical conditions.  So far the "youngest" patient who died in the US was 40 and had leukemia and was undergoing chemotherapy.

Further comparisons to the H1N1 virus are in order to put the current pandemic into some perspective.  During the last few "swine flu seasons", late fall through early spring 2010-2013, about 30,000,000 Americans contracted the virus per year, 300,000 of those patients require hospitalization per year and about 30,000 died, again, per year. This is shown in CDC chart form below.    Last year's flu season was the worst (so far) of this century.                                                                                           

The second CDC chart below shows numbers of hospitalizations due to flu; the red curve is this year and as you can see, at least so far, we are well within seasonal norms.  This WILL change but supports the earlier statement that panic and hysteria are not indicated.  In comparative terms, the CDC estimates that influenza has resulted each year in between 9 million and 45 million illnesses, between 140,000 and 810,000 hospitalizations and between 12,000 and 61,000 deaths annually since 2010.  Compare that to the 33,404 cases of COVID-19 and 400 deaths since this virus entered the US population.


The next important question is who should be tested with the limited number of test kits currently available? The CDC recommends that clinicians use their judgment to determine if a patient has signs and symptoms compatible with COVID-19. Most symptomatic patients with confirmed COVID-19 have developed fever and/or signs of acute respiratory illness (e.g., cough, difficulty breathing). Priorities for testing may include:

  1. Hospitalized patients who have signs and symptoms compatible with COVID-19 in order to form decisions related to infection control.
  2. Other symptomatic individuals such as older adults and individuals with chronic medical conditions and/or an immunocompromised state that may put them at higher risk for poor outcomes (e.g., diabetes, heart disease, receiving immunosuppressive medications, chronic lung disease, chronic kidney disease).
  3. Any persons including healthcare personnel, who within 14 days of symptom onset had close contact with a suspect or laboratory-confirmed COVID-19 patient, or who have a history travel to an endemic area within 14 days of their symptom onset.

How this virus is transmitted is also a very valid concern.  This is clearly a community-acquired infection; simply put that means you catch it from someone who already has it.  It is transmitted from person to person by breathing in exhaled viral particles from someone who has an active infection or contacting an infected surface.  Similar to other viral pathogens, COVID-19 appears to have a short viability period outside the body of the carrier.  Here again some hysteria has entered to fill the vacuum of facts.  The virus appears to be viable AND infectious in an aerosolized form for only a few minutes to about an hour and can live and remain infectious on hard surfaces for a few hours to about a day.  Again this is comparable to both influenza A and B viruses that survive for 24-48 hours on hard, nonporous surfaces such as stainless steel and plastic but survived for less than 8-12 hours on cloth, paper, and tissues. Measurable quantities of influenza A virus were transferred from stainless steel surfaces to hands for 24 hours and from tissues to hands for up to 15 minutes. Viable viral particles survived on hands for up to about 5 minutes after transfer from environmental surfaces.  Understanding these numbers is important.  Current news coverage of this pandemic does not take into account that just because the virus can be identified on hard surfaces does not mean it can be grown and is in an infectious form.  It is only that the DNA strand, or a part or it, can still be identified chemically.  Once again, without widespread testing it is just not possible to make too many factual statements about this strain of virus.

An important point to keep in mind is that along with the fact that the disease is community-acquired goes the fact that community-acquired immunity and resistance will follow. This is why we simply do not know how dangerous this virus truly will be. But as of statistics released just this morning, it seems that about 98% - 99% of patients who are infected with the virus do not get sick, so the rate of community acquired resistance to this pathogen appears to be quite high.  This also will change with more testing and it may increase or decrease.  At this time, this virus appears to be treatable with standard anti-viral medications such as Tamiflu and acyclovir that we have used during other flu outbreaks.  These medications are not vaccines. Testing on subjects has started (and it is remarkable how fast we have been able to get a prototype vaccine available) but a vaccine to impart immunity to COVID-19 will not be ready for this flu season.  Other medications are being found to help treat the virus but, again, all that is pretty early.

I have reviewed the most rigorous CDC guidelines for hospitals and healthcare professionals and the CDC check list is linked here. It is certainly indicated to apply these standards to your workplace and homes starting today.  A number of logical and practical actions can be taken.  First, as during every flu season, stay home if you feel sick.  Wash your hands with soap and water often, as it is more likely to acquire the virus from a surface (where it lives longer) than a nearby patient! Soap will uncoil and inactivate the virus but equally important as soap is volume of water and the time you wash.  The more copious the amount of water the better.  Hand sanitizers also are useful but be aware that the commercially available hand sanitizers work only after DRYING and not when they are still wet so if you use a hand sanitizer keep in mind your hands are not clean until all the chemical has completely dried. You can also use a chemical wipe towel to clean your hands but make sure you use an alcohol-based wipe, not "baby wipes" that are not effective viral killers.  Given that wipes are hard to come by and all the commercially available hand sanitizers are pretty much sold out at the moment, you can instead use an EPA-registered disinfecting spray, such a Clorox or alcohol based spray.  A link to this list from the Center for Biocide Chemistries is here.  You can even make yourselfa hand sanitizer solution according to the CDC by mixing 4 teaspoons bleach per quart of water. 

Another very useful solution is to mix isopropyl alcohol (rubbing alcohol) with a small amount of hydrogen peroxide and a small amount of aloe or other skin lubricant. Diluted household bleach solutions can be used if appropriate for the surface. Follow manufacturer’s instructions for application and proper ventilation. Never mix household bleach with ammonia or any other cleanser. Unexpired household bleach will be effective against coronaviruses when properly diluted.  You can prepare a bleach solution by mixing 5 tablespoons (1/3rd cup) bleach per gallon of water or 4 teaspoons bleach per quart of water.  NONE of these products should be ingested as they are all only for hand and surface disinfection.  In public places keep your hands in your pockets not sliding along handrails or holding on to handles and keep your hands away from your face ALWAYS.

Surgical masks are pretty much USELESS, and the CDC has good evidence to show that using these masks probably INCREASES your risk of infection!  Surgical masks are not "ventilator" masks that biohazard workers use.  For one thing, surgical masks do not prevent you from inhaling anything in the atmosphere. They only redirect pathogens to the sides instead of the front of your face.  They do not filter or sterilize the air; you just breathe in air from the side and not straight in front of you.  They are designed only to prevent surgeons from exhaling directly into surgical wounds.  They are also really uncomfortable and as a surgeon who has lived most of my adult life in surgical masks I can attest to that fact.  If you are not used to wearing a surgical mask you tend to put your hands to your face a lot to adjust them.  As the viability studies of this virus detailed above show, the virus does not live long in aerosolized droplets but can live up to 1-2 days on hard surfaces so all you do with a mask is bring potentially infective virus particles to your face where you can catch the disease that you are not very likely to have inhaled in the first place.  If you see someone in a surgical mask the safest place for you is right in front of him or her since they're exhaling out the side of the mask.  With all that said, "social distancing" is an important aspect to prevent spread of all diseases with an air-borne vector and this virus can certainly spread in that manner.  Even though the viability of the virus in the air appears to be short it doesn't take long to get infected if someone carrying the virus coughs on you.

In conclusion, your health, your family's health and the health of everyone around you should be your primary concern.  As pilots, we know when there is an emergency in the cockpit panic will cripple our capacity to solve the problem and bring our airplane to a safe landing.  There is no doubt that this health emergency is real and likely to get worse, but solving this problem is not all that different from aviation emergencies that we practice for all the time.  Let's keep our heads and fly ourselves out of this emergency just like all the emergencies we have talked about and practiced for all these years.   Next year at this time we will all have had our COVID-19 vaccines and this will be an unpleasant but distant memory.

Kenneth Stahl, MD, FACS

Kenneth Stahl, MD, FACS is an expert in principles of aviation safety and has adapted those lessons to healthcare and industry for maximizing patient safety and minimizing human error. He also writes and teaches pilot and patient safety principles and error avoidance. He is triple board-certified in cardiac surgery, trauma surgery/surgical critical care and general surgery. Dr. Stahl holds an active ATP certification and a 25-year member of the AOPA with thousands of hours as pilot in command in multiple airframes. He serves on the AOPA Board of Aviation Medical Advisors and is a published author with numerous peer reviewed journal and medical textbook contributions. Dr. Stahl practices surgery and is active in writing and industry consulting. He can be reached at [email protected].

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