7 ms·
As suspected, it's exactly a probability game. If there's few infectious particles sure to low concentrations (e.g. people distance or are outdoors), you would
by AstralStorm 5y ago
As suspected, it's exactly a probability game. If there's few infectious particles sure to low concentrations (e.g. people distance or are outdoors), you would roll the 70% penetration chance fewer times, and result in very few particles reaching deeper into lungs too as the velocities are reduced.
When very close to an active particle source, you'd roll the conditional probability dice many more times.
The critical number is the base infectivity or viability. (CFU essentially) It is expected that sub-viable numbers might even work as a kind of vaccination if people isolate long enough. (stay at home for prolonged time without contact - scale of days at least)
- epivosism 5y agoYes. Crazy how hard it has been for people to get this: Imagine a bulletproof vest with three larger-than-bullet-sized holes in it. Say you know someone is going to shoot ten bullets at you - would you not wear the vest because "the attack vector can fit through the pores"? The point is people treat this as a binary 'safe' / 'not safe' switch, when actually risk is related to the distribution of exposure to dosage.
- ppf 5y agoIf we're talking about the size of the holes in a mask compared to a virus, then it would be more like wearing a "bulletproof" vest full of holes 10x bigger than a bullet.
- epivosism 5y agoBut the area which does have coverage is still significant, right?
- epivosism 5y agoI guess it's a choice of analogy. If virus particles are like bullets, protection can be viewed as proportional. But if it's viewed more like a liquid, seeping through any hole, then only full watertight protection works. I'd argue that the reduced transmissibility we see from outdoor exposure supports the first of those as a more apt analogy.
- nradov 5y agoThere is no evidence that inoculation with sub-viable numbers of virions works at all as a kind of vaccination. It's an interesting hypothesis but no one has done the human challenge trials necessary to test it.