So what's the big deal about taking unproven therapies?

Well, with convalescent plasma, the most recent study https://www.medrxiv.org/content/10.1101/2020.08.12.20169359v1 showed 8.7% survived if given treatment in first 3 days, 11.9% survived if treated day 4 to later.

Convalescent plasma is a blood product

This doesn't mean this is a treatment you can take in the first 3 days of illness. Most people who develop COVID feel well the first few days of illness.

The study looked at those who were hospitalized w/severe disease in the first 3 days of diagnosis.

So it doesn't mean is a treatment that lets you avoid getting sick or be hospitalized.

It isn't a treatment that has been studied to avoid severe illness - nor could it easily be.

Instead, this is a blood product
- and while we're on the topic of novel infections and outbreaks, remember blood products though generally safe, require work to remain safe and this should never be overlooked
- there are also risks of allergic reactions w/blood products

Convalescent plasma is a treatment that the scientific community has had optimism about, but it's impact is more modest than would have been hoped.

The one RCT w/ a placebo showed no significant improvement in 28 days after therapy https://jamanetwork.com/journals/jama/article-abstract/2766943

There's also the issue that not everyone makes the same quality antibodies. Convalescent serum from one donor may not be the same as from another donor. This isn't a factory produced drug. This is a blood product.

It may be that in the future we have a monoclonal antibody that can play the role we would like convalescent plasma to play, but in the meantime, we still need more info to know what plasma can do https://www.nih.gov/news-events/news-releases/clinical-trials-monoclonal-antibodies-prevent-covid-19-now-enrolling