I think the point parent is making is slightly different. Let me try to re-phrase it negatively: What we don't know about mRNA vaccines we don't know about SARS

I think the point parent is making is slightly different. Let me try to re-phrase it negatively: What we don't know about mRNA vaccines we don't know about SARS-CoV-2 either. Our state of knowledge of the effects of SARS-Cov-2 will soon be eclipsed by our knowledge of the effects of mRNA vaccines. SARS-Cov-2 is only 6 months older than the mRNA vaccines. There will always be unknown unknowns for both mRNA vaccines and SARS-Cov-2.