[mansr]

Verifying the expected immune response (antibodies) is (part of) phases 1 and 2, if I've understood things correctly.

[DiogenesKynikos]

Exactly. It's a good sign if people develop antibodies, but that does not ensure protection. As I understand it, it is difficult to predict, in advance of actual testing, what immune response will actually be protective.

[dry_soup]

I see, thanks!