I like your airplane analogy, Drew. It works for the N95 masks, too, in that 5% of the airborne particles still make it through the mask. WRT efficacy rates, though, 5% of 220,000,000 people is still 11,000,000 cases of CV19, 1% of which, or another 110,000 will die. If that 5% turns out to be the difference between one dose and two, we'd better stick with two, IMHO.
But, from what I've read, the clinical trials that have started are still being monitored to help determine the long term effects. I haven't read of any trials, other than the J&J, that administered only a single dose. And with the J&J vaccine, efficacy was only 90%, so you lose that 110,000 folks right up front. Given the choice, I'd pick one of the two dose vaccines. But since there seems to be a supply issue, until it's resolved we'll have to stick with the hand sanitizer, face masks, and social distancing discipline. From what I saw in town yesterday, more and more people are ignoring those simple precautions.
I did find some N95 face masks last week. Not on Amazon, who is restricting their sales to those in essential areas, but from ebay, which apparently has no such scruples. They're a new type I haven't tried before, and were designed to fold flat for easy transport. That makes them a little more fiddly to put on, but I think they fit better, and they're a lot easier to breathe through than my previous mask that I've been using for almost 18 months. Here are the order details:
Order date: 2/11/2021 - eBay user globedrug ( 834 )
Order total: $22.28
3M Aura 9205 Plus N95 Particulate Respirator Disposable Protective Mask (5 Pack)
You should get this by Mon, Feb 22.