https://twitter.com/statesdj/status/1252698777296797698
Reality-check thread on vaccines. No idea if this guy is a major expert but he at least raises a lot of interesting ideas that might merit more investigation.
People are using Rt to talk about net rate of transmission. Ro is supposed to be some inherent number but it seems to me it has to be conditions specific.
So anyhow the actual rate of transmission would be impacted by herd immunity. The higher inherent Ro the more percent needed to get to herd immunity.
Think how easy it transmits x how many available to transmit to. (Which is 1-% immune). If it transmits readily then it takes less possible people to get a transmission.
If the ease of transmission in virus A means 10 hosts are needed to guarantee a transmission, virus B with a higher Ro might only need 5?possible hosts.
(Iām out speculating some here, I think the concept is correct but not sure exactly how the math works, gets beyond standard microbiology growth equations).
In a bacterial fermentation infected with phage, each phage replication cycle can generate 100-200 new phage and the kill can be 99.9999%. You end up with more phage than bacteria. And the survivors are likely mutants that have some resistance. By the time you know itās happening to full kill is 45 minutes. Quite spectacular when the tank covers the parking lot in foam from all the cell lysis.
At least this thing needs people in proximity to people. My bacteria were 1 billion+ cells in each millimeter. No social distancing there.
Some patients are unable to clear the virus: https://www.reuters.com/article/us-health-coronavirus-china-patients-ins/recovered-almost-chinas-early-patients-unable-to-shed-coronavirus-idUSKCN2240HI
I assume these patients who canāt shake the virus have to be at least somewhat contagious this whole time - or they wouldnāt be testing positive. But I really hope someone is doing a study on just how contagious they are on average. If itās a lot - thatās terrifying.
If all the evil world leaders were to die of this I might have to believe in a higher power.
Got it. So in theory R0 is some idealized constant for the virus that isnāt even impacted by population density?
Seems like if so weāre talking about the wrong number all this time and should be talking about Rt.
That sure lends credence to the weaker strain theory. You would really think thereās no way in hell that whatever hit NYC/Italy could be in community transmission for that long and it not be obvious.
Unless Californians are just a lot more resistant for some reason to the worst symptoms. Maybe below freezing air not only boosts contagion it boost severity somehow. Or it boosts initial viral load which boosts severity.
This is where Iām not sure but it seems to me it has to be at some assumed number of people to people interaction per time unit.
Ro is replication multiplier for a virus assuming a normal society with no vaccines or intentional distancing. R is the multiplier with everything factored in. Herd immunity is when R drops below 1.0.
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Yes but there must be an assumption for what normal society is? A medium size US city? Tokyo at weekedays? Rural France? The outback (crikey?).
So density, level of public transport, level of large gathering like church sports and entertainment?
See what is missing in the simple definition?
I was blocked by a Deplorable Staten Island pediatric nurse who was enraged that anyone would āpoliticizeā the COVID crisis, especially since she knows it kills equally regardless of oneās politics, race, SES, etc.
Yes, if we used that time to increase production of supplies, from trusting to hospital beds. We arenāt doing that very well, though
Sometimes the weekend is three days, sometimes itās two days, sometimes there a dip in the middle of the week.
Normal society is whatever population you are trying to measure.
Mother of God.
French researchers to test nicotine patches on coronavirus patients
[Quote]
Study ā which stresses serious health risks of smoking ā suggest substance in tobacco may lower risk of getting coronavirus. [/Quote]
It must be a society-specific measure.
So Ro is different in bumfuck Iowa vs NYC?
Which according to Wikipedia is the case
- R 0 is not a biological constant for a pathogen as it is also affected by other factors such as environmental conditions and the behaviour of the infected population.*
There canāt be an absolute measure of Ro if itās dependent on human behaviour. Youāll have one Ro for a whole country and another for an individual area.
When behaviour in either of those cases change (eg quarantine) R for that case reflects the new multiplier and Ro remains as a benchmark, though may be updated when conditions change (eg quarantine revoked).
Thatās just my understanding of it.