Not exactly .. safety was established in HIV trials, efficacy suggested in M/M... It's going to be behind REGN & perhaps LLY's P/MABs for obvious reasons, but it should be ahead of HGEN and That Sham Company.

My question is: what reference spike protein REGN's used; if it's from six months ago, what are the odds the strain Trump and associates have has mutated, and what would REGN's PAB's binding affinity be as a result?

Reinfections may be a function of adaptive immunity decreasing over time, but genetic sequencing has shown mutations from first and second infections. Viral protein-targeting P/MABs largely have the same issue as classic vaccines in that regard.