> This is why you have a flu vaccine every year, but chicken pox once. It's somewhat rare, but it would have been possible for your friend to have gotten a different variant, or act as a carrier for a different variant. He chose to follow expert advise to keep himself and others safe.

There's a couple of things wrong in this statement that circle back to the religious belief statement earlier.

Firstly, the use of keep himself and others safe. That's a specious as talking about computer security in terms of safety instead of risk, which is a far more insightful, nuanced - and most importantly - useful way of looking at this. He could never again drive nor allow his family into or near any kind of motor vehicle and that would make them more "safe" but would it be rational? That would require a discussion of risk and its trade offs.

Next, you'd have to show antigenic escape against natural immunity. There is some, and it's very small[1]:

> Because the data in the system were person-identifiable, the authors were able to determine that 3·27% of those who were uninfected during the first surge had a positive test during the second surge, compared with 0·65% among those who had previously recorded a positive test. Thus, they determined from that, in general, past infection confers 80·5% protection against reinfection, which decreases to 47·1% in those aged 65 years and older.

So, again, we're back to looking at risk instead of safety (and that Lancet article is straining to argue that natural immunity isn't enough, a very poor effort in my view, just look at citation 11).

There's also not much evidence of the high level of mutation seen in other coronaviruses because of the method of replication[2]:

> In contrast to the rapid evolution of other RNA viruses, SARS-CoV-2 has low genomic variability because of its proofreading function

A good thing because it means the vaccines are showing good efficacy against variants too.

Lastly, because I don't know if you're arguing in good faith (seriously, just respond to comments, starting off with such a slight makes me question you more than anyone else) you'd then need to show what that reinfection could mean in terms of consequence - will you experience symptoms? Will you end up in hospital? Will you end up in ICU? Will you need a respirator? Could you die? Is there a change in transmissability?

Again, a risk assessment. Feel free to provide this and show that the person sat there in a mask, who I assume is of working age and therefore in the cohort with greater protection from reinfection, is not behaving irrationally.

Perhaps they really do never get into a car, never go out in a thunderstorm, and wear a hard hat whenever they leave the house. Still, in the absence of other, competing and compelling data, to sit there believing you're keeping yourself and those around you safe by continuing to wear a mask is irrational and not based on "leading research" at all.

And you're going to tell me he knows any of this? Please.

Btw, both of these are worth a read, and citation 11 of each, too ;-)

[1] https://www.thelancet.com/journals/lancet/article/PIIS0140-6...

[2] https://www.nature.com/articles/s41591-021-01347-0