[lamontcg]

> Given that immunity eventually wanes and new variants show up

Immunity isn't one thing that wanes.

T-cells are largely permanent and cross-reactive. Somatic hypermutation means that you have B-cells to variants which don't exist yet which can be quickly activated if you encounter them.

There's more to the immune system than circulating NAbs.

The 2009 H1N1 flu pandemic was a bit of a nothingburger because after mutating in pigs for at least 50 years, people born before 1957 still had cross-reactive T-cells to the H1 protein so old people were already immunized.

This is not the human immune system's first goat rodeo with a pandemic virus.