How safe is public transit?
Is it safe to take public transit at a time like this?
I’ve noticed that while, earlier on, there were general warnings that masks don’t necessarily work to stop transmission, now everyone talks as if they do.
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Kate
Reply
Alison Cummins 10:24 on 2020-05-11 Permalink
Masks definitely slow transmission.
1. They keep your filthy paws out of your face. This stops you rubbing virus into your nose and stops you smearing your face goo on things other people might touch.
2. Homemade masks are fairly good at capturing droplets (mostly what leaves your face). This is where “my mask protects you, your mask protects me” comes in.
3. Homemade masks are not so good at filtering aerosols (what’s left floating around in the air after droplets fall to the ground). They offer some protection in this direction but not a lot.
Masks must not be wet. They must cover as much of your face as possible.
If everyone wears a mask, passengers on public transport should be ok. Drivers… less so.
Alison Cummins 10:27 on 2020-05-11 Permalink
Excellent article on evaluating risk:
https://www.erinbromage.com/post/the-risks-know-them-avoid-them
Alison Cummins 10:48 on 2020-05-11 Permalink
Question to anyone who knows this stuff:
When scientists say it takes 200–1000 virus particles to cause an infection, what does that mean exactly?
Is it that our bodies are pretty good at neutralizing virus particles and there’s only a 1/1000 chance of a lucky particle making it all the way into a cell? Like it only takes one sperm to cause a pregnancy, but the chances of any given sperm making it to an egg are so low that a sperm count of less than 15M/mL can be a fertility problem?
Or does the virus need a critical mass of infected cells to propagate? Like a little virus patch that can spread, vs a single infected cell that can be easily identified and neutralized?
jeather 10:56 on 2020-05-11 Permalink
The former, Alison, more or less — we are good at fighting off infections, but we have a limited number of white blood cells, so the more virus particles you have in your system the more likely some of them can continue to propagate before the WBCs kill them and the cell they are in.
Tee Owe 15:43 on 2020-05-11 Permalink
Nice explanation Jeather – I like Alison’s fertility/sperm count analogy, might use it in teaching. Important to not confuse those first-line WBC with the antibody immunity that we all hope for, that comes later, if we’re lucky
Alison Cummins 18:47 on 2020-05-11 Permalink
Kate, thanks, but there’s no thought to complete. Just stray words, possibly from an aborted paragraph.
Alison Cummins 22:50 on 2020-05-11 Permalink
Thanks, jeather! That makes sense.