What we (don’t) know about convalescent plasma treatment for Covid-19

On Aug. 23, the US Food and Drug Administration gave emergency use authorization (EUA) to convalescent plasma as a therapy for hospitalized Covid-19 patients.

EUAs allow the FDA to bypass normal approval procedures when a treatment could benefit many people in an emergency—like a pandemic. Before, convalescent plasma was only available for patients being treated as part of a limited “expanded access program” (more on that in a bit), or in compassionate-use cases.

If convalescent plasma works, the EUA could save thousands of lives without regulatory red tape. But without rigorous, controlled testing, doctors are left to make educated guesses about how exactly to use the treatment. Here’s what we know so far about convalescent plasma, and, just as important, what we don’t.

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