Dear Reader:

In this post (and future posts) I will refer to the coronavirus responsible for the 2002-2003 SARS epidemic as Cov-1 (short for SARS-Covid-1), and to the coronavirus responsible for the current SARS pandemic as Cov-2, short for SARS-Cov-2. I will refer to the SARS epidemic of 2002-03 as SARS,(Severe Acute Respiratory Syndrome), and to the current SARS pandemic as Covid-19 (Coronavirus Disease 2010).

www. businessinsider. com/ china-Wuhan-coronavirus-compared-to-sars-2020-1(paraphrased by me, plus quotes): The two viruses: Cov-1, responsible for the SARS epidemic of 2002-2003 (WHO declared the epidemic contained on July 5, 2003), and Cov-2, responsible for the current SARS pandemic (Covid-19) of 2019-?, share 80% of their genetic codes. The two viruses are zoonotic, meaning, they jumped from animals to humans. The original hosts of both were bats. Both were passed through the saliva and poop of bats to intermediate animals before jumping into humans.

Both Cov-1 and Cov-2 enter the host cell of animals/ humans by bonding to receptors in the animal/human lung cells, receptors that are called ACE2. But Cov-2 forms a bond with ACE2 that is ten times stronger than the bond Cov-1 formed with same receptor. This 10 times stronger bond between Cov-2 and the human lung receptor ACE2, can explain why Covid-19 is “so much more contagious than SARS and more easily jumps from person to person”.

Cov-2 “is nearly identical to other coronaviruses circulating in Chinese bat populations- 96% of the genetic codes match”.

www. medicalnewstoday. com/ articles/ how-do-sars-and-mers-compare-with-covid-19:

A summary comparison of SARS vs Covid-19:

* total number of cases-  SARS: 8,439 (87% of all cases were in China and Hong Kong, 29 countries and territories total); Covid-19 (current): 2,228,784. (264 times the number of SARS total cases, in 210 countries and territories).

* Number of cases in the U.S-  SARS: 73; Covid-19 (current): 686,431. (9,403 times the number of U.S SARS cases).

* Total number of deaths- SARS: 812; Covid-19 (current): 150,708. (185 times the number of SARS deaths).

* Case Fatality Rate (CFR)-  SARS: 9.6% (11% according to Wikipedia); Covid-19 current estimates: varies, most about 1.38%- 3.4%, SARS therefore has “significantly higher case fatality rates than Covid-19. Yet Covid-19 is more infectious” (Wikipedia: SARS Ro= 2-4, Covid-19: “Initial studies suggested ..a basic reproduction number of 2.2-2.7, but a study to be published on April 07, 2020 calculated a much higher median Ro value of 5.7%”). Ro is a basic reproduction number indicating how many people are infected by one infected person.

* The following are the same or similar for both: mode of transmission (droplets produced by breathing, talking, sneezing, coughing), mean incubation period (5 days), key symptoms are similar, and in both people with underlying medical conditions were/ are a risk group.

www. webmd. com/ lung/ news/ ..sars-timeline-of-outbreak(quotes):

Nov 16, 2002: the first case of an atypical pneumonia is reported in the Guangdon province of Southern China.

Feb 26, 2003: first cases of unusual pneumonia reported in Hanoi, Vietnam.

..March 11, 2003: a similar outbreak of a mysterious respiratory disease is reported among healthcare workers in Hong Kong.

March 12, 2003: WHO (World Health Organization) issues a global alert about a new infectious disease of unknown origin in both Vietnam and Hong Kong.

..March 15, 2003: CDC (US Center for Disease Control and Prevention) issues a travel advisory stating that persons considering travel to the affected areas in Asia (Hong Kong, Singapore, Vietnam and China).

March 17, 2003: an international network of 11 leading laboratories is established to determine the cause of SARS and develop potential treatments. And CDC holds its first briefing on SARS and says the first 14 suspected SARS cases are being investigated in the U.S.

..April 28, 2003: WHO removes Vietnam from list of SARS affected areas, making it the first country to contain SARS successfully. WHO also lifts travel advisory to Hanoi, Vietnam.

May 6, 2003: the CDC lifts its travel advisory for Singapore because no new cases of SAR had been reported in 20 days.

..May 17, 2003: WHO extends its travel warning to include Hebei Province, China.

..May 20, 2003: the CDC lifts its travel alert for Toronto, Canada, because more than 30 days have elapsed since the last case of SARS was reported there.

May 23, 2003: the WHO lifts its advisory against all but essential travel to Hong Kong and the Guangdong province of China saying the SARS situation in those areas has  improved significantly.

..June 24, 2003: WHO removes its last remaining SARS travel warning for Beijing, China.

My thoughts based on the above:

1. Coronaviruses, like all viruses, mutate. Cov-2 has 80% of the genome of Cov-1 which has been contained 17 years ago. Cov-2 has 96% of the genome of coronaviruses recently found in bats. This means that (very roughly and in a very simplified way), the virus mutated 16% in 17 years.

2. Both SARS and Covid-19, started in China: SARS started in China’s Guangdong Province, November 2002, and Covid-19 started in China’s Hubei Province (Wuhan), December 2019. SARS spread mostly in China and Hong Kong, and to total 29 countries and territories. Covid-19 spread to 210 countries and territories, and produced 9,403 more cases of infections so far, 185 times more deaths so  far.

Even though a higher percentage of Covid-1 infections ended in death (its mortality rate/ Case Fatality Rate/CFR is higher), Covid-2 produced 185 times more deaths than Covid-1, so far, because it is more contagious:

A lower percentage/CFR of a higher number of infections (because of a higher Ro) gives a bigger number of deaths than does a higher percentage/CFR of a lower number of infections (because of a lower Ro). In other words, a higher infection rate when not contained, and a lower mortality rate results in more deaths than a lower infection rate and a higher mortality.

3. The events of Nov 2002 through June 2003, a few of which I included above, are similar to what I expect to happen next during this pandemic, in that WHO, the CDC and other official organizations in different countries, will announce, as time goes by, new travel alerts, travel advisories, social restrictions, removals of alerts, removal of advisories, removal of restrictions, re-establishing alerts and restrictions and so on and on, in different areas within a country, in different countries, according to changing data, until a vaccine becomes readily available to the world population.

* On May 20, 2003, the CDC lifted its travel alert to Toronto, Canada  because “more than 30 days have elapsed since the last case of SARS was reported there”. There were about 400 cases of SARS infection in Canada, but more than 31,000 Covid-19 cases of infection in Canada currently. I imagine the CDC will not wait 30 days of having no new Covid-19 cases in any area before lifting a travel alert. I imagine alerts and restrictions will be lifted when the number of new infections per day, in an area, over time (the flattening of the curve) lessens, rather than the unimaginable, pre-vaccine situation of having zero new cases anywhere.

* In March 17, 2oo3, for the first time “an international network of 11 leading laboratories” was established to determine the cause of SARS (Cov-1) and develop potential treatments. Seventeen years later, a whole lot more laboratories, and international networks are working on studying Cov-2, developing treatments (shorter term) and vaccines (longer term). A lot more attention and resources are put in the effort now than 17 years ago.

More later.

anita

• This reply was modified 4 years, 8 months ago by .