I have had a number of people ask me about the coronavirus pandemic. I have put together this list of major points. If you have questions about COVID-19 please go to the most authoritative web sites for information and avoid the rest. The Center for Disease Control (CDC) and the World Health Organization (WHO) are the two best sites. I have also found that Johns Hopkins, the Mayo Clinic and Harvard Medical School sites were excellent places to find accurate information. Three secondary sites that have done a very good job of synthesizing and summarizing information on COVID-19 are the newsletter of the scientific journal Nature, the daily science news publication The Scientist, and The New York Times.
(the above picture, by the way, is me and my grandson, Ari, and my daughter Marian when we attended Joe and Marlee’s wedding this past December. Life is good!)
- There are seven “coronaviruses” known to affect humans. Four of these infect cells in the upper respiratory tract and cause what we call the “common cold.” On average, people in North America get infected with these four corona viruses and “catch” colds three time a year.
The other three corona viruses (the “SARS” virus, the “MERS” virus and the new virus that causes COVID-19) cause much more serious, respiratory illnesses.
These viruses were named “corona” because of the protein projections off of the “body” of the virus making the virus look like a crown or like the corona of the sun.
The COVID-19 virus enters the mucosa cells of the respiratory tract via the ACE2 receptor protein (which are found on many types of body cells but which are very abundant on cells lining the lower respiratory tract)
Other organs of the body (whose cells also have the ACE2 receptor) may get infected with COVID-19 and may be damaged during the body’s vigorous immune response to the virus
- (the following is a synopsis of a March 12, 2020 article in the NYTimes that outlines the COVID-19 cycle in the human body):
When the virus enters a cell it hijacks the cell’s metabolic machinery and stimulates it to make many more copies of the virus. The viral load in the cell results in the cell’s death with the subsequent release of synthesized viruses and cellular debris. Immune system reactions to the infection generates first symptoms (sore throat, dry cough, fever, etc.)
These new viruses continue to spread down respiratory tract infecting more and more cells causing more and more severe symptoms. Infection of the cells in the lungs (bronchioles and alveoli) can lead to pneumonia.
NOTE: about 80% of individuals infected with the COVID-19 virus have mild symptoms (infection stays in the upper respiratory organs (it behaves like a common cold). 20% of infected individuals, though, get lower respiratory tract infections with much more serious symptoms. Approximately 2% of individuals infected with the COVID-19 virus die.
- A person infected with the COVID-19 virus will frequently cough and sneeze due to mucous membrane irritations caused by the virus. These sneezes and coughs will expel tiny droplets of water that are packed with viruses. These droplets can travel about 6 feet from the infected individual. This distance is the logic behind the idea of keeping one’s “social distance” when out in public.
(the following is from experiments conducted at the National Institute of Health (NIH)):
These droplets are relatively large and, so, will not stay suspended in the air for very long (but exactly how long this suspension lasts is not clear from experimental reports).
The viruses can remain viable in these droplets maintained in a laboratory-generated aerosol for about 3 hours.
Droplets landing on plastic or stainless steel surfaces may remain viable for 2 to 3 days
Droplets landing on a more porous surface (cardboard) remain viable for 24 hours
Droplets landing on fabric surfaces (like blankets?) are said to remain viable for even shorter periods of time according to the Mayo Clinic (but no experimental data was found to support this)
- Experiments at the Johns Hopkins Bloomberg School of Public Health (published in the Annals of Internal Medicine on March 10, 2020) indicated that people exposed to the COVID-19 virus, on average, began to show symptoms in 5.1 days. 97.5% of exposed patients showed symptoms within 11.5 days (hence the logic of a 14 day quarantine following exposure)
- A study at the Bundeswehr Institute of Microbiology (Munich Germany) recently released in a pre-print on Med Rxiv indicated that many of the examined COVID-19 patients had upper respiratory infections (and associated “common cold”-like symptoms). All infected patients, though, regardless of the mildness or severity of their symptoms, actively were producing and shedding viruses. The first five days with symptoms had the maximum rate of viral production and release, but viruses continued to be shed for up to one week after symptoms had abated.
- The most common way for the virus to be passed from an infected individual to a new host is via contact with the viral-laden droplets
Most of these transmissions are direct transfer of freshly expelled droplets to the mucous membranes (eyes, nose, mouth) of the new host. This requires close contact between the infected individual and the new host. In China most of the COVID-19 virus transfers were between infected patients and healthcare workers or between infected individuals and their family members.
Droplets from the respiratory tract of an infected individual may also be abundantly present on that individuals face. Hands and face touching , then, may be a mechanism to spread the virus from infected individuals to surrounding surfaces or to other individuals. Un-infected individuals may also transfer viral-laden droplets to their own eyes, noses or mouths via face touching. Face touching, then, is a mechanism for both spreading and indirectly infecting individuals with the virus!
DON’T TOUCH YOUR FACE!!!
- Soap: coronaviruses are encased in a lipid rich envelope. Soaps and detergents emulsify these fatty envelopes and very effectively kill the virus. Vigorous washing with soap is a very effective way to cut off hand dissemination or transmission of the virus (there is an excellent article in The Guardian (March 12, 2020) by Paul Thordarson called “The Science of Soap.”
- Disinfectants: surface disinfectants (alcohols, hydrogen peroxides and bleaches) are extremely effective at killing coronaviruses. These are tools that can cut down on the indirect spread of the viruses (but keep in mind that the DIRECT spread of viral droplets is the much more frequent pathway for infection!). For a very complete discussion of disinfectants and hand sanitizers see the March4, 2020 article by Compound Interest entitled “Corona virus: how hand sanitizers protect against infection.” Also note: hand sanitizers are very easy to use but washing your hands with soap is the most effective way to kill corona viruses!
- Death rates: in 2003 the SARS virus had a death rate of 10%
In 2012-2019 the MERS virus had a death rate of 23%
the 2019-2020 COVID-19 virus has a death rate of approximately 2%
COVID-19 is, apparently, much more easily transmitted than either the SARS or the MERS viruses and has infected many more people and already accounted for more deaths than both of these earlier viruses combined.
For comparison: the flu virus (which is a completely different virus from these coronaviruses) infects a very large number of people every year. The CDC estimates that last year 35.5 million people in the United States contracted flu. Of these 34,200 people died from flu or flu complications. That generates a death rate of approximately 0.1%.
- Examination of the death rates for COVID-19 in the initial outbreak in China indicate that elderly individuals (over 60 years of age) and individuals with pre-existing health conditions (cardiovascular disease, diabetes, chronic respiratory disease, hypertension or cancer) had higher death rates (7.3 to 10.5%) than younger, healthy people (1% death rate). Although deaths occurred in all age groups (except for children under 9 years of age) few children had serious symptoms. Deaths were thought to come about primarily due to uncontrolled activity of the immune system.
Men had a higher average death rate than women (2.8% vs. 1.7%). This may be due to gender differences in the ACE-2 receptor used by the virus to enter cells. The gene for the ACE-2 protein is on the X chromosome. So, women have two potential copies of the ACE-2 allele while men only have one. An even more compelling explanation for the elevated male mortality, though, may lie in the fact that men in China are much more likely to smoke than are women. China has the largest smoking population in the world (316 million smokers), and 51.1% of the Chinese male population smokes compared to just 2.7% of Chinese women.