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The USFDA has put on hold its decision to issue emergency approval for blood plasma therapy as a COVID-19 treatment, the New York Times reported on Wednesday.
A group of top federal health officials, including Dr Anthony Fauci and Dr Francis Collins, have argued that the emerging data on the treatment was too weak for the approval.
However, this isn't the end of the road for blood plasma therapy, as the USFDA could still grant approval in the near future based on more data.
Fauci is the director of the National Institute of Allergy and Infectious Diseases and a member of the White House coronavirus task force. Collins is director of the National Institutes of Health (NIH).
What happens in the US on the medical front is keenly observed across the world. Currently, plasma therapy is being tested in India and globally through the World Health Organization (WHO) Solidarity Trial.
What is plasma therapy?
Plasma is the yellow liquid that remains after cells are removed from blood. Plasma contains antibodies involved in regulating immune responses.
Convalescent Plasma Therapy involves transfusion of the plasma of a recovered COVID-19 patient to treat those critically affected by the coronavirus. Some of these antibodies, which may have helped the donor recover from COVID-19, could help the infected person kick-start his recovery.
Thousands of COVID-19 patients in India are now being treated with blood plasma. Social media frequently has messages from COVID-19 patients' family members or friends seeking plasma donations.
Why did the USFDA put plasma therapy on hold?
The experts who have objected to the USFDA's emergency authorisation have pointed to the lack of robust data on the efficacy of the treatment through randomised control trials.
A randomised control trial (RCT) is considered the gold standard for any treatment, as it compares outcomes for patients who are randomly assigned to get the treatment with those who are in a control group or given a placebo.
The biggest study undertaken on plasma therapy, involving 35,322 patients who received transfusions, is an open-label observational study by the Mayo Clinic funded by the US government.
In an Open Label study participants and researchers both know which treatment is being given to the participant. In contrast, a Double Blind study is one in which neither the participants nor the researchers have this information. Blinding is not possible in a plasma therapy study.
The three-month open-label study found overall mortality lower for patients who received plasma. The report also said that in a subset of the cohort (3,082 patients), the lower mortality was associated with plasma transfusions that contained higher levels of antibodies against the virus that causes COVID-19.
But one huge limitation with the study was that there was no control group or placebo group, which would have helped determine the efficacy of plasma therapy.
What is the status of blood plasma therapy in India?
Convalescent plasma therapy in India has been listed as an investigational therapy for off-label use in COVID-19 infected patients because there is no conclusive evidence as of now on its efficacy. Interestingly, India is conducting a phase-2 open-label randomised controlled trial called PLACID to assess the safety and efficacy of convalescent plasma in limiting the complications associated with COVID-19.
Most institutions that took part in the Indian Council of Medical Research's (ICMR) trial on plasma therapy have found blood transfusions from recovered COVID-19 patients to those with moderately severe illness to be effective. An Indian Express report says that out of 52 institutions participating in the ICMR PLACID trial, the daily spoke to principal investigators of 36 institutions, of whom 24 said plasma therapy was effective.
However, an interim analysis by the All India Institute of Medical Sciences (AIIMS) of the randomised controlled trial found no benefit in reducing mortality. The study stated that mortality is similar, with not many clinical benefits in both arms (the one that received plasma and the one that didn't). The sample size of the study was 30 patients. The final report on the ICMR study is awaited.