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.
First up, the executive summary's context section in its entirety:
"The SARS-CoV-2 virus can spread in several ways: through zoonotic transmission, direct and indirect contact transmission, direct deposition transmission, and inhalation or airborne transmission. An increasing body of evidence [28]–[31] suggests that it is transmitted through infectious fluids released from an infected individual as particles of different sizes and quantities, such as during breathing, speaking, coughing and sneezing. While the largest particles travel downwards quite rapidly, the smaller ones remain suspended in the air for longer periods and can travel farther distances. When people are in close proximity, transmission of infectious particles can occur through direct inhalation (short-range) and deposition onto the mucous linings of the respiratory tract and ocular membranes of a susceptible host particularly in the absence of face covers and ventilation. ‘Long-range’ transmission can occur in enclosed settings when infectious particles accumulate over time in a given volume, where the concentration of virions is sufficient enough to cause infection once infectious particles are inhaled by a susceptible host."
Right off the bat we get to why I think this is so important and it's not JUST airborne transmission. A lot of time has been spent arguing methods of infection. This document acknowledges things like deposition onto the ocular membrane.
Why is this important? The science doesn't lie. Politicians and minimizers can ignore it, but, eventually they'll probably have to acknowledge it. In the meantime, you have another tool at your disposal to understand the science AND to help calculate your risk.
Would I rely on the percent given by the calculator as THE exact risk? Of course not. Do I think it's important that this document, and calculator exist? I do. I believe in science.
