Big thank you to @EricCarroll for pointing out this new WHO document on SARS-CoV-2 transmission.
This document is pretty complex, in-depth, dense, and I still expect it to evolve as we learn along the way. They have some of the correct people to be working on this, for once. Hello Lidia Morawska signing off on it at the beginning of the forward.
First, a tldr. If you don't care about how it came to be, or the science, and just want to know the outcome, here it is:
https://partnersplatform.who.int/tools/aria
Go to the calculator, enter your data, and come out with a probability of infection in a given situation along with the number of expected secondary infections from that interaction.
Here's the document itself if you want to follow along:
https://iris.who.int/bitstream/handle/10665/376346/9789240090576-eng.pdf?sequence=1&isAllowed=y
Disclaimer - This is evolving science.
I'm going to split this up in a thread, because I took a lot of notes of what stood out to me on a first read, and I hope to come back to it, and use it as a general reference moving forward.
But, hey, what about different variants? That's a whole thing. While I was doing this my wife was playing around with the calculator, and that's definitely one of the major limiting factors right now, but, let's see what they had to say about it.
"Variants of Concern
Of the six variants currently designated as VOI, five were considered in the analysis and among these only B.1.617.1 and B.1.525 demonstrated a statistically significant increase in the effective reproduction number of 48% (95% CI: 28–69) and 29% (95% CI: 23– 35), respectively.
Given the widespread co-circulation of VOC/VOI, the effective reproduction numbers of these variants were compared against each other in order to estimate the nature of future competitive growth between them. Notably, the pooled mean difference in the effective production number between the VOC B.1.1.7 and B.1.351 was small at 4% (95% CI: 0–8), while P.1 demonstrated an increase relative to B.1.1.7 and B.1.351 of 10% (95% CI: 3–17) and 17% (95% CI: 6–30). Given these estimates, the longer-term trends of competitive growth between these three VOC remain unclear. In contrast, the rapid observed growth of B.1.617.2 suggests a clear competitive advantage compared with B.1.1.7, B.1.351 and P.1, with estimated increases in the effective reproduction number of 55% (95% CI: 43–68), 60% (95% CI: 48–73) and 34% (95% CI: 26–43) respectively [145].
...
A systematic review shows that the effective reproduction number and basic reproduction number of the Omicron variant elicited 3.8- and 2.5-times higher transmissibility than the
Delta variant, respectively. The Omicron variant has an average basic reproduction number of 9.5 and a range from 5.5 to 24 (median 10 and interquartile range, IQR: 7.25, 11.88). The average effective reproduction number for Omicron is 3.4, with a range from 0.88 to 9.4 (median 2.8 and IQR: 2.03, 3.85) [147]."
Like I said, evolving science.
