Of course, any time some security measure works, there is an immediate response that the whole thing was overblown. (I always think back to the Michelangelo virus, which would have been a major disaster had we not managed to get warnings and attention out to the public in time. The day of the hit, there were already media stories saying the whole thing was a hoax.)
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There is no need to keep fretting over every possibility either or until the science is a bit more conclusive. I doubt at this time anyone is really denying hand washing works to stop the spread of any germ based organism save a few insane folks out in population. Wearing homemade masks at 1-20 percent filtration is nothing but an exercise in security theater at this point as well. Not that we shouldn't but don't expect these types of measures to have any real effect. Many of us have already had the disease and lived to tell the tale. I have at least one co-worker still in the hospital, more than one familiar member with apparent but untested symptoms. So what? Complain that we have been subjected to a number of poor detection rate tests? The FDA didn't use the early tests because they had an unusually high rate of false negatives. We have better testing now, even in my area of Chicago where we have seen a significant death toll. This has only been available to us since, well, today: 17Apr20! At the very least we can now consider the testing to be reliable. Something not seen during the first months of this crisis.
As for the physical deniers out there. Take notice of them, protect yourself and your family first. If your not out your not likely to come in contact with these few individuals in the first place.
As I have said for many years, now. We are all risk managers of our own lives. Some people just do better at handling risk than others.