[alexpw]

The mRNA vaccines were developed to target the spike protein of the Alpha variant. We got lucky it works so well against Delta, or else they would have had to roll out a new vaccine.

Based on your wording, it sounds like you have the mistaken impression that the mRNA vaccines are expected to account for and target all future variants. A future variant may have a large enough mutation to the spike protein and render them 0% effective. But they can rollout a new vaccine very quickly with EUA. Sorry if I've misinterpreted.

I don't remember ever seeing #s promising long term effectiveness, but eventually later seeing a chart with projected effectiveness waning over time. What they should do is be careful to present variant specific numbers. There's too much generalizing, like I did as well, lumping Pfizer and Moderna together.