I was always under the impression that the increased transmissibility of Delta with lower fatality rate was an example of that classic example of viral mutations selecting for less severity in order to maximize chances of retaining available hosts. I recently read somewhere (I think an article by a Hawaiian physician) that this is actually a "myth"? I had never heard that before.

But in any case I don't know how you could look at the vaccination curve alongside Delta and conclude vaccines get credit for the (thankfully) still-lower CFR.

Moreover, what about India? Still abysmally (or blessedly) low rate of full vaccination and Delta seems not to be hitting them particularly hard past that first wave.