Convalescent plasma, or plasma from someone with anti-sars-cov-2 antibodies, has been considered as a treatment option since early on in the pandemic. For a while now, the data around the use of high-titer plasma has been leveling off with the conclusion that it has very little to no effect on slowing disease progression.
This article published in NEJM earlier in August looked at 511 patients in the emergency room either being treated for Covid-19 with high-titer convalescent plasma or a placebo. It was found that around 30% of both groups (30.0% and 31.7% for plasma group and placebo group, respectively) showed disease progression (meaning hospitalization, seeking emergency care, or death). This indicates that the use of plasma did not provide protection from worsening disease.
The diagram featured in this post is illustrating the disease severity diversity of each group and highlighting that the plasma treated group was nearly identical to the placebo group. Each rectangle is indicating a particular severity status ranging from not hospitalized to death (visit the link to this article on my website to see exact definitions of each group)!