What I really want to know about #covid19 beyond the fatality rate:

>R0: is it 2.7? 3? 5?
>Hospitalization rate among infected
>Temp/Perm disabling rate among infected.

Many people don't realize that a disease can be dangerous at the macro level without killing a lot of people

Even if #covid19's overall fatality, hospitalization, and disabling rates are low as %ages of infected, if it spreads faster than the flu, then the absolute #s of each will all be higher.

A disease with an average R0 of will infect 16 people four generations after a single infected (1×2×2×2×2)

R0 of 3 will result in 81 over the same span (1×3×3×3×3).

So even small differences at the individual level can result in huge ones on a larger scale later. #covid19

Now, people don't move around in space like inanimate particles. As news of an outbreak spreads, they will alter their activities to lower the risk to themselves.

Otherwise an entire city of 60,000 would be infected after 11 generations of a disease with an R0 of 3. #covid19

So in a localized area like a city or county, the R0 will decrease after time, but by then, the necessary damage might be done. #covid19

R0 of 3 after 5 generations=81
After 11=59049
If R0 lowered to 2 after 5 generations, after 11 it is 5184
(1×3×3×3×3×2×2×2×2×2×2)
#covid19

I still think polio is a good #covid19 comparison. Highly infectious 5-7 R0 but extremely low death rate of 0.08% and paralyzing rate of 0.5% of all cases.

>70% had no symptoms, another ~25% had flu symptoms. These were "subclinical cases". Only paralytic cases usually reported.

Naturally, denser, larger cities would be hit harder than more spread out rural areas, and numbers could vary some base on year and location.

But generally, 99.5% of all polio cases involved no paralysis. 95% or more had no worse than the flu. 99.92% survived. #covid19

So for the NYC polio epidemic of 1916 in a city of about 5mill, there were about 9000 paralytic cases and 2000 or so deaths.

The real incidence of the disease was likely near 1.8mill, if paralytic cases were about 0.5% of all cases. #covid19

NYC shutdown during that summer--for a polio outbreak that paralyzed/disabled ~0.18% and killed ~0.04% of the total city population of ~5mill.

Every year from 1916 until 1955, polio epidemics hit cities across the United States. Houston had one almost every other year from 1937-1955, for example.

Some cities shutdown just like many places today. Some only shutdown gatherings, schools, and quarantined all kids. #covid19

But regardless, past generations were more than familiar with the concept of shutting down to protect against an epidemic. Did it hurt? Yes, but they were more concerned about protecting themselves from vicious diseases than preserving the economy. #covid19

Polio, to my mind, is a great example *because* it killed and disabled so rarely, but places still partially or entirely shut down in order to protect people from it. #covid19

This thread is really a continuation of my previous thoughts on polio and #COVID19. https://mobile.twitter.com/Jake_W/status/1251435899407253505