If having COVID in the past conferred no immunity at all, and you were just as likely to get it again as you were the first time, we would have hundreds of thousands of double-COVID cases in the U.S. alone.

We don't have that, or anything remotely close to it.

We have maybe a handful of scattered double-cases. I sometimes see conscientious, educated people take those handful of scattered cases way too seriously.

However, those people rarely have a background in
either medicine/immunology or in math/stats.

The medicine/immunology/biostats people are almostall very bullish on the idea that your immune system will protect you from reinfection.

However, they're bearish on a "herd immunity" strategy because it would take many many more people getting sick.

Near-unanimously, really.

And what I like best about this is they've shown their work and explained both points well.

Unsurprisingly, your immune system tries to learn from experience, and usually it succeeds.

On the herd immunity strategy they've done the math and explained it pretty clearly.