A Primer to SARS-COV2 and COVID-19

Dr. Rumi Ahmed Khan March 1, 2020 coronaviruses, COVID-19, SARS-CoV2
A Primer to SARS-COV2 and COVID-19

We know the term coronation. Coronation comes from corona – corona is Latin of Crown. Coronavirus is named such because it looks like a crown under a microscope!

The virus we all are worried about is a coronavirus. Name of the Virus is SARS-CoV2 and Name of the disease it causes is called COVID-19. 

The coronavirus is the second leading cause of the common cold (after rhinoviruses) and until recent decades, rarely caused any disease more serious than a common cold in humans. The coronaviruses are responsible for about 10-30 percent of colds worldwide. 

So far Seven human coronaviruses (HCoVs) have now been identified: HCoV-229E, HCoV-OC43, HCoV-NL63, HCoV-HKU1, SARS-CoV (which causes severe acute respiratory syndrome), MERS-CoV (Middle East respiratory syndrome), and now this new talk of the town: SARS-CoV-2. Long known to cause only upper respiratory infections, the last three in the above list i.e. the three most recently developed coronaviruses are being seen to cause pneumonia. 

What do we mean by recently developed coronaviruses?

Many viruses constantly change their genetic configuration. In flu viruses also we also see such changes called genetic shift, drift thus leading to gene reassignment. 

Sometimes coronaviruses are usually found in animals like bats which go through some genetic modification and start infecting humans. Those then become new novel human coronaviruses. In the last three decades we had three such events  – MERS-CoV (the beta coronavirus that causes Middle East Respiratory Syndrome, or MERS) spread into humans from camels. SARS-CoV (the beta coronavirus that causes severe acute respiratory syndrome, or SARS) spread to human from bats and third one is this 

2019 Novel Coronavirus (2019-nCoV) – we still don’t know from where this virus came to humans.

As a result of such gene reassortment – a new virus developed against which humans or animals don’t have any antibody. Until humans or animals develops antibodies to the new viruses, the diseases cases lots of morbidity and mortality and spreads fast. In 2009 when as a result of gene reassortment a new type of flu virus called 2009H1N1 started attacking humans.  Because it was a new virus, humans didn’t have anybody to it and as a result the virus affected almost 20% of the world’s population killing around 300000 people worldwide and nearly 13000 in the USA only. Because humans developed antibodies and annual flu vaccination protects against 2009H1N1 virus, this virus now a days cause very mild disease. 

So when scientists discovered this new coronavirus which is genetically nearly 95% identical to the SARS coronavirus that caused the 2002 SARS epidemic, they assumed that this new virus resulted from gene reassortment of a coronavirus that usually swelled in bats. 

Like 2009H1N1, because this is a new virus – initially it is expected to cause much higher morbidity and mortality compared to future years. 

The coronaviruses are spread through the air by coughing and sneezing or by Close personal contact, such as touching or shaking hands or by Touching an object or surface with the virus on it, then touching the  mouth, nose or eyes without washing your hands. 

What do we mean by recently developed coronaviruses?

  • One Ebola patient infects 2 person
  • One flu patient infects 1.3 to 2.5 person
  • One COVID-19 patients infects 2.5 persons with Coronavirus ( SARS-COV2)
  • One SARS patient infected 3.5 persons
  • One mumps patient infects 7 persons
  • One measles patient infects 20 persons

We still don’t have a vaccine against this new trait of coronavirus.  Although some drugs are undergoing experimentation, there’s no proven treatment yet. 

So our best bet is mitigating efforts. 

CDC talks about mitigation in three buckets:

  • 1. Individuals behaviors (hand hygiene, staying at home, avoiding ill people);
  • 2. “Social distancing” (closing schools and public gatherings, and
  • 3. Environmental mitigation (surface cleaning efforts).

Encouraging better individual hygiene behaviors is a cornerstone of mitigation. Good hand hygiene (wash those hands!), and voluntary home isolation when ill (and even home quarantine when potentially exposed) are recommended. Many studies show the effectiveness of hand hygiene; one study on H1N1 from Egypt highlighted by CDC showed 47% fewer cases of influenza occurred after twice-daily hand washing and health hygiene instruction was provided in elementary schools. Studies of the US public during H1N1 found that people actually did change their hygiene behaviors: in one survey 59% of Americans reported washing hands more frequently and 25% said they avoided public places like sporting events, malls, and public transportation.

CDC guidelines also support social distancing in some cases, including school closures, canceling public gatherings, and workplace closures/telework.

Rumi Ahmed Khan MD FCCP

Rumi Ahmed Khan MD FCCP is an Associate Professor of Medicine at University of Central Florida College of Medicine. He is also Fellowship Program Director at Orlando Health Pulmonary Critical Care Medicine and Director of Pulmonary Function and cardiopulmonary exercise physiology laboratory, Orlando Health, Orlando. Florida

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