Covid-19: How it Spreads and How it can be Slowed

[Palmpilot]

I posted these links in a thread that is now closed. I was hoping that someone knowledgeable could comment on the methodology and/or conclusions:

Differential Effects of Intervention Timing on COVID-19 Spread in the United States

https://www.medrxiv.org/content/10.1101/2020.05.15.20103655v1.full.pdf

Coronavirus: Here’s how germs are spread and where you’re most likely to catch them

https://www.weforum.org/agenda/2020/05/coronavirus-covid19-exposure-risk-catching-virus-germs/

 

[PeterNSteinmetz]

I posted these links in a thread that is now closed. I was hoping that someone knowledgeable could comment on the methodology and/or conclusions:

Differential Effects of Intervention Timing on COVID-19 Spread in the United States

https://www.medrxiv.org/content/10.1101/2020.05.15.20103655v1.full.pdf

On a first reading, here are the things that I would look into more deeply.

They do not appear to have compared the counties with and without coercive lockdown measures, which would have been interesting.

Their calculation of the effective Rt does strike me as about right.

They don’t mention the timing in that brief statement of the results but it does agree roughly with what I have observed as well. Social distancing started fairly early, likely based on news reports. There is a general trend toward decreased Rt a few days to weeks later (depends on the state when looked at that way).

 

[PeterNSteinmetz]

Out of curiosity, what exactly are you reading to get that?

Certainly hasn’t been true for vast majority of southern states. Arizona is skyrocketing and temps have been around 110F.

Yes, likely pretty hard to deconvolve the various factors right now and attribute to one cause or another.

 

[PeterNSteinmetz]

I have been curious about the reported bump in cases recently, particularly in my state of AZ. So I just downloaded the case data (covidtracking.com) and re-computed the estimates of Rt, the estimated daily analog of R0 for the observed growth of cases in each state. The following is a graph of that estimate by calendar day for each state. AZ seems to have had a bump right around Memorial Day but is heading back down. And in none of the states are the values heading up toward the sort of large values we saw in some states in March and April. (Values above 1, the dotted line, correspond to growth of reported cases whereas values below are decreasing numbers of new cases.)

 

[PeterNSteinmetz]

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7108646/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2440799/

conclusions might surprise some people.

There are a lot of factors which could potentially help or hinder the efficacy of cloth mask usage by the general public. There are over 100 publications on this subject now. So for non-professionals not wanting to read all that, I recommend looking at the 4 reviews presently in pre-print form as well as the discussion in the BMJ on these factors.

I placed links to these on my medical page today after giving a talk. Available at http://steinmetz.org/peter/Medical/index.html .

Overall about a 50/50 mix of whether a good or bad idea. In my talk I said definitely an area where reasonable people and scientists might disagree.