4 ms·
Fewer particles admitted means reduced chance of infection, no? The thing to keep in mind is that blocking 50% of the particles does not mean a 50% reduction i
by chlodwig 5y ago
Fewer particles admitted means reduced chance of infection, no?
The thing to keep in mind is that blocking 50% of the particles does not mean a 50% reduction in infection. It may mean a 50% reduction in infection -- or it may mean a basically zero percent reduction. It depends on the exposure.
Say that in a particular covid-filled room you have a 50% chance of being infected after 5 minutes and a 99.9% chance of being infected after an hour. Under a simple model, if you wear a mask that blocks half the particles, your chance of getting coronavirus in 5 minutes would be reduced to 25%, but your chance of getting it after an hour would be 97%. So if cloth mask is your primary defense against covid, you are eventually going to get covid if you are trying to live anything close to a normal life. Blocking 50% of particles is like wearing an condom that only blocks 50% of the sperm or an umbrella that blocks only 50% of the rain.
- elmalto 5y agoI don’t think anyone is advocating for masks as your only line of defense, just one of a few (vaccines currently being the best)
- kube-system 5y agoPregnancy is boolean. A person's viral load is not a boolean value. The umbrella is a better comparison. My umbrella doesn't prevent 100% of the rain from coming in contact with me. This is good enough that the umbrella is still standard practice.
- chlodwig 5y agoAre you referring to the theory that the severity of covid has a dose-response relationship with the infectious inoculum? It's an interesting theory, but I think it is far from proven. It's a shame that it's not studied, because if true it might actually make sense to just give everyone a very small infectious inoculum as a form of vaccination.
- kube-system 5y agoThe infectious dose of viruses is usually not (never?) a single particle. Depending on the virus, it may be tens or hundreds of particles required to infect a person. We don't know an exact number for COVID, but we know that it's likely some number that's greater than one. Whatever that number is, if we limit the number of particles in the air, we decrease the statistical probability that a person will come in contact to a number of particles exceeding that number. It's a "solution to pollution is dilution" issue. > it might actually make sense to just give everyone a very small infectious inoculum as a form of vaccination. The biggest issue with this, as I understand, is straddling the line between causing an immune response and hurting the patient. There are live vaccine viruses, but most (all?) attenuate the virus to prevent the latter.
- scythe 5y agoA model with misleading values can easily reach misleading conclusions. If there were any places where the chance of infection reaches even 50% after an hour, there would be huge, obvious outbreaks associated with people going to those places. The actual observed spread of SARS-CoV-2 has been much slower than this; a basic reproduction number of 7 together with a duration of two weeks means that the average infected person behaving like an average American in 2020 will infect 0.5 persons per day (I'm being generous). This counts situations like e.g. someone becomes infected and goes home to their family and literally lives there. Even in those situations it moves slowly. Or, to put it more on the nose: the half-life for an American getting CoViD under ordinary conditions seems to be longer than a year. Using your linear model, a 50% mask would make it more than two years! So half-life exhaustion doesn't seem an appropriate counterpoint.