How Virulent is COVID-19?

How Virulent is COVID-19?

Here’s the summary my personal research into the science of COVID-19. 

This is so I can educate myself, friends and family and help debunk the proliferation of unscientific nonsense.

So let’s get a bit techie and look at the numbers! 


Definitions

R0 (R Nought) is the “Basic Reproduction Ratio” of a pathogen. The expected number of cases directly generated by one case in a population where all (non-infected or immunized) individuals are susceptible to infection. 

https://en.m.wikipedia.org/wiki/Basic_reproduction_number

  • R0 > 1 :  Pathogen spread grows
  • R0 = 1 :  Pathogen spread stable
  • R0 < 1 :  Pathogen spread reduces (dies out)

The larger the R0, the faster the reproduction rate. 

Example: R0 = 2

  • 2 people will each infect 2 others
  • Let this happen just 5 times
  • Infected = 2x2x2x2x2 = 32

Incubation Period: The time from infection to illness. 

Serial Interval (SI): Time taken for one R0 cycle. The mean period between symptom onset in an infector and an infectee.

The serial interval of COVID-19 is close to or shorter than its median incubation period. This suggests that a substantial proportion of secondary transmission may occur prior to illness onset. -PubMed-

Transmission: All the following pathogens are transmitted via airborne droplets.


R0 – Viral Comparisons

The Scary Numbers

The following should show you why COVID-19 is WAY more virulent (severe or harmful) than the ‘Flu. and just a bit less virulent then the 1348 Bubonic Plague!

Black Death – 1348 (Yersinia pestis)

  • R0: 3 (2.8-3.5)
  • 10 cycles = 59,000
  • 15 cycles = 14 million
  • 20 cycles = 3.5 billion
  • Mean SI:: 4 (2-7) days
  • World Population (1348): 475 million
  • Infected: 150+ million (30%+)
  • Killed: 50 million (10%)
  • Targeted: Everyone!

~ 120 days (30 x 4) to potentially infect half the world!

They had NO idea what caused it (miasma) or any treatments to slow the spread and deaths.

Spanish Flu – 1918 (H1N1)

  • R0: 2.0 (1.4-2.8)
  • 10 cycles = 1024
  • 15 cycles = 32,768
  • 20 cycles = 1 million
  • 25 cycles = 34 million
  • 30 cycles = 1 billion
  • Mean SI:: 4 (2-7) days
  • World Population (1919): 2 billion
  • Infected: 500 million (25%)
  • Killed: 100 million (5%)
  • Targeted: 20-40y/o

~ 120 days (30 x 4) to potentially infect half the world!

They had NO idea where it came from or any treatments other than isolation. 

Viral Influenza – Seasonal Flu (A,B,C,D)

  • R0: 1.3 (0.9-2.1)
  • 10 cycles = 14
  • 15 cycles = 51
  • 20 cycles = 190
  • 25 cycles = 705
  • 30 cycles = 2,620
  • 60 cycles = 6.8 billion
  • Mean SI: 2 (1-4) days
  • World Population (2019): ~8 billion
  • Annual Infected: ~500 million
  • Annual Serious: ~5 million
  • Annual Deaths: ~500,000
  • Targets: Young, Old, Pregnant, Compromised

~ 120 days (60 x 2) to potentially infect an unprotected world.

But we now have treatments, vaccines AND isolation to slow the spread and deaths. 

COVID-19 (SARS-CoV-2)

  • R0: 2.5 (1.4 – 3.9)
  • 10 cycles = 9537
  • 15 cycles = 931,000
  • 20 cycles = 91 million
  • 25 cycles = 8.88 billion
  • Mean SI:  5.5 (3-14) days (WHO)
  • World Population (2019): ~8 billion
  • Infected: ~1 million (so far)
  • Killed: ~100,000 (so far)
  • Targets: Everyone! (Especially Health Compromised)

This means COVID-19 could take only 137 days (25 x 5.5 ) to potentially infect a completely unprotected world!

We currently have NO treatments and vaccines (only isolation and distancing) to slow the spread and deaths.


Are you now going to #StayAtHome ?

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