Thoughts on Novel Coronavirus(COVID-19)

As stated in my profile, I am a practicing physician.  As the Novel Coronavirus(COVID-19) grew into a pandemic, I debated writing a post about it.  Developments over the last 48 hours directly impact the Giants and MLB, so here it is.  I will try to stick to facts as I know them.  Any opinions I express are my own and not necessarily those of the leadership of my employing medical group or my profession.

If you look at the entirety of human history, pandemics of infectious diseases have played an enormous role.  For centuries, they were likely the major reason why the human population of Earth remained relatively low and stable.  It is only in the last 200-300 years that they have become rare and this rarity is a major reason why Earth's population exploded.  This dramatic decrease in the frequency and severity of pandemics is due to equally dramatic developments in our understanding of transmissibility, basic public health and hygiene, anti-infective medications and vaccines.  Long before COVID-19 showed up, I believed the single biggest threat to our civilization is a major pandemic due to a deadly respiratory virus like influenza or COVID-19.

The last major deadly pandemic due to a respiratory virus occurred in 1918, almost exactly 100 years ago when an antigenic shift produced a new influenza virus which killed millions of humans worldwide.  Every year, influenza kills thousands of humans.  The reason why it does not kill millions is the vast majority of humans have at least partial immunity through prior exposure to similar viruses and vaccines which produce both individual and herd immunity.  The reason why another antigenic shift would likely kill millions is the the body's immune system does not recognize it as a foreign invader which delays an effective immune response.  Interestingly, if you plot case-fatality ratio(CFR) vs time for the 1918 Influenza pandemic, it is bimodal with one peak at about 48 hours and another at 10-14 days.  The first peak occurred most frequently in young healthy men ages 20-40 and was believed to be due to an overwhelming immune-mediated pneumonia.  The second peak was due to secondary bacterial pneumonias.  Remember, the 1918 influenza pandemic occurred prior to vaccines and antibiotics or antiviral medications.

While not an exact replica, the current COVID-19 pandemic resembles the 1918 influenza pandemic more closely than anything we have seen in the intervening years.  Coronaviruses are a family of viruses which cause respiratory flu-like illnesses which we see fairly frequently on an ongoing basis.  What makes COVID-19 different, is likely an antigenic shift for which there is no individual or herd immunity.  Unlike influenza, we have not previously developed vaccines or antiviral agents against coronaviruses.  This creates a perfect environment for a major deadly pandemic.

The numbers are scary.  Worldwide, the CFR(Deaths/Confirmed Cases) remains remarkably stable at approximately 3.5%(by comparison, the CFR for seasonal influenza not due due an antigenic shift is approximately 0.1%).  Estimates of real CFR including unconfirmed cases are closer to 1.0-1.5%, but in Italy which has an older population, the reported CFR is around 7%.  Incubation period is 5-6 days(compared to 3-5 for influenza).  Number of secondary infections generated from one individual is 2-2.5(higher than influenza).  While a secondary infection ratio of 2:1 does not seem so bad, this virus remains highly contagious.  In one town in New York, 80 cases have been traced to 1 individual.  Another cluster of cases in the Boston area grew out of a single conference attended by employees of a biomedical company.  Transmission is through direct contact, droplets(produced by breathing, cough or sneeze) and fomites(dormant viruses  on contaminated surfaces).  Approximately 80% of infections are mild or asymptomatic, but 15% are severe(requiring oxygen) and 5% are critical(require ventilation support).

Extrapolation of these numbers leads to some truly frightening projections.  If the virus spreads unchecked, it will likely infect a minimum of 30% of the population.  U.S. population is approximately 350 million which means 100 million infected.  A CFR of 3.5% would produce 3.5 million deaths.  A CFR of 1% would produce 1 million deaths.  It does not appear that this virus is losing transmissibility or virulence over time.  At this point, our only current hope of avoiding these catastrophic numbers is to limit transmission rates.  An effective vaccine will likely take at least months to develop and an effective antiviral medication remains elusive.

It appears China successfully blunted the spread of the virus through reportedly draconian quarantine measures which go far beyond anything even contemplated in the U.S up to this point.  Current measures such as cancelling the NBA season and the Coachella Festival are likely just the beginning of restrictions which will go far beyond anything any of us have ever experienced.  How effective these measures prove to be remains to be seen.  Early in my career, I had a patient who remembered living through the 1918 influenza pandemic.  She lived on a remote farm in Missouri approximately 20 miles from the closest neighbor.  She lost half her immediate family.

I receive many requests for my personal recommendations for avoiding COVID 19 and many readers here may have the same question.  Here is what I currently recommend:

1.  Follow directions from the CDC and local authorities.

2.  Avoid gatherings of people such as hotels, conferences, church services and entertainment events including sporting events. Avoid mass transportation, planes, trains, buses, etc.  DO NOT BOOK ANY CRUISES for the foreseeable future!  Avoid popular tourist sites.

3.  Remember droplet radius is 3-6 feet.

4.  Use of masks is controversial.  All I can say is for years droplet precautions in my hospital involve wearing a simple surgical mask.  Of course, we take the mask off and wash our hands immediately upon exiting the room.  I don't know if wearing a mask at all times would be as effective.  It is unlikely that N95 masks are more effective than a simple surgical mask which is effective against direct inhalation of droplets.

5.  Wash hands after every contact with another person or surfaces which may be contaminated. Avoid handshakes!

6.  Although I am not aware of foodborn transmission, droplets containing the virus could theoretically remain on uncooked food for a long time.  Avoidance of uncooked food is a consideration.  Fast food is probably safer than a sit-down restaurant and the drive-through window is probably safer than physically entering the restaurant.

7.  If you develop cough and fever, you should immediately self quarantine until you can be tested(testing should become more readily available in the next few days).  If possible, put on a mask or some type of facial covering before presenting to a healthcare facility for evaluation.

8.  Much as I hate to say it, you probably should postpone routine medical visits.

While panic is never helpful in a crisis, it is appropriate to maintain a vigilant respect for the ability of this virus to produce mass casualties and take appropriate steps to protect yourself and others.