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.