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Explained | Why USFDA has put plasma therapy for COVID-19 on hold and what it means for India

A group of top US health officials, including Anthony Fauci, have said that the emerging data on the treatment was too weak for the approval.

August 22, 2020 / 12:45 AM IST

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?

COVID-19 Vaccine

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A vaccine works by mimicking a natural infection. A vaccine not only induces immune response to protect people from any future COVID-19 infection, but also helps quickly build herd immunity to put an end to the pandemic. Herd immunity occurs when a sufficient percentage of a population becomes immune to a disease, making the spread of disease from person to person unlikely. The good news is that SARS-CoV-2 virus has been fairly stable, which increases the viability of a vaccine.

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There are broadly four types of vaccine — one, a vaccine based on the whole virus (this could be either inactivated, or an attenuated [weakened] virus vaccine); two, a non-replicating viral vector vaccine that uses a benign virus as vector that carries the antigen of SARS-CoV; three, nucleic-acid vaccines that have genetic material like DNA and RNA of antigens like spike protein given to a person, helping human cells decode genetic material and produce the vaccine; and four, protein subunit vaccine wherein the recombinant proteins of SARS-COV-2 along with an adjuvant (booster) is given as a vaccine.

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Vaccine development is a long, complex process. Unlike drugs that are given to people with a diseased, vaccines are given to healthy people and also vulnerable sections such as children, pregnant women and the elderly. So rigorous tests are compulsory. History says that the fastest time it took to develop a vaccine is five years, but it usually takes double or sometimes triple that time.

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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.

Viswanath Pilla
Viswanath Pilla is a business journalist with 14 years of reporting experience. Based in Mumbai, Pilla covers pharma, healthcare and infrastructure sectors for Moneycontrol.
first published: Aug 21, 2020 03:01 pm