President Trump has announced FDA emergency approval of blood plasma taken from people who have recovered from Covid-19 as a treatment for the disease. Although the move will increase the number of people who have access to the plasma, it is not equivalent to full FDA approval.
As with so much about the virus, the approval process has become politicized, with supporters of the president claiming the FDA is going slow to harm Trump's re-election chances, while many experts in the field argue the evidence is currently insufficient that the treatment actually works.
The idea of taking blood from infectious disease survivors to assist the vulnerable dates back at least as far as the 19th century, and is familiar enough that science fiction novels have been built around the idea. Plasma contains the antibodies that provide some of the immune system’s protection against disease and is easier to transport and store than whole blood but misses out on the T-cells, the other component of the body’s resistance.
Convalescent plasma was tried during the original SARS outbreak, with results considered encouraging but not conclusive, and recently against Ebola. Naturally, immunologists were quick to propose it once the seriousness of Covid-19 became clear.
On Sunday, President Trump announced the emergency approval, calling it “historic” and “a breakthrough”. In the same speech, he hinted at an announcement about vaccines “shortly”, claiming the response was years ahead of where things would have been under past administrations.
“Over 100,000 Americans have already enrolled to receive this treatment and it has proven to reduce mortality by 35 percent,” Trump said. “That's a tremendous number.” He also called for patients who have recovered to volunteer to donate their blood via coronavirus.gov.
Convalescent plasma is considered a safe treatment, and compared to pharmaceuticals still under patent is relatively cheap. It is already in fairly widespread use prior to the emergency approval, leading some commentators to call the announcement a stunt to coincide with the start of the Republican National Convention rather than a major development. Trump's tweet from just two days ago has been raised as evidence for this view.
Trump’s proclaimed benefit apparently refers to encouraging results from a yet peer-reviewed observational study by the Mayo Clinic.
However, one randomized controlled trial, considered a more reliable test, had more modest results and was terminated early. Meanwhile, two large controlled trials underway are yet to produce findings. In a statement, Professor Zoe McQuilten of Monash University, the lead Australian researcher of one international study, said that “until such trials are completed and reported, the effectiveness of convalescent plasma remains uncertain.”
Dr Gaetan Burgio of the Australian National University was even more blunt, saying: “This emergency authorisation is, unfortunately, not based on proven scientific grounds and is even dangerous.”
However, the Kirby Institute's Professor Raina MacIntyre noted: “Other treatments such as Remdesivir have been [granted emergency authorization while testing continues], so it is reasonable to offer convalescent plasma in the same way."
Several scientists argued that, even if the convalescent plasma is found to work, significant research is yet to be done to establish an appropriate dosage and which patients will benefit most. At least, however, people will find it harder to self-administer than hydroxychloroquine.
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