Experts: It’s too early to say if plasma therapy works against COVID-19

Infectious disease expert Dr. Carlos del Rio discusses the recent FDA approval of convalescent plasma and what recent studies point to regarding the treatment.

Convalescent plasma, granted emergency authorization to be used as a treatment for COVID-19 and touted by President Trump as a breakthrough, has yet to be proven effective and needs more rigorous study, some experts in Atlanta and across the country said Monday.

The Food and Drug Administration’s action will increase COVID-19 patients’ access to plasma therapy, which involves harvesting and injecting antibodies from people who have recovered from the illness. Convalescent plasma has been used at hospitals in metro Atlanta and around the country as part of a research program run by the Mayo Clinic and sponsored by the federal government.

Trump, who had expressed frustration at the slow pace of approval for coronavirus treatments, announced the FDA’s decision on Sunday. The agency’s emergency authorization is not the same as approving the treatment as safe and effective.

As for whether the treatment is a “game changer,” said Dr. Carlos del Rio, an Emory infectious disease specialist, “the evidence is not there.”

Dr. Amy Hajari Case, medical director of Pulmonary/Critical Care Research at Piedmont Healthcare, agreed. While convalescent therapy has shown promise, the evidence so far has not been conclusive as to whether it works, when it should be administered, and what dose is needed, she said.

Doctors have expressed concern about political influences on the FDA.

“To me, the emergency authorization sounds political,” said del Rio. “I hope the FDA is able to maintain its scientific integrity. Our safety depends on it.”

Scientists also challenged Trump’s claim that the Mayo Clinic study on the treatment had “proven to reduce mortality by 35%.”

Before the authorization, White House officials had suggested that there were politically motivated delays by the FDA in approving a vaccine and therapeutics for the disease. The Trump administration’s handling of the coronavirus pandemic has come under fire by Democrats, who are quick to bring up perceived failures on the campaign trail.

Convalescent plasma is a century-old treatment that was used to fight off flu and measles outbreaks in the days before vaccines. And it was tried more recently during the Ebola outbreak. When the body encounters a new germ, it makes proteins called antibodies that target the infection. The antibodies float in plasma — the yellowish, liquid part of blood.

Plasma therapy works differently than a vaccine. When a person gets a vaccine, their own immune system actively produces antibodies to attack a pathogen. That’s called active immunity. Convalescent therapy offers what’s called “passive” immunity. It “borrows” the antibodies from someone who has successfully fought off the disease.

Before the development of antibiotics and vaccines, plasma therapy was used for a range of infectious diseases, including the Spanish flu in 1918, as well as meningitis and measles. During the 1918 flu pandemic, the rate of mortality decreased by as much as 50 percent among patients who received convalescent plasma, according to a meta-analysis of medical records available at that time and published in the Annals of Internal Medicine in 2006.

Plasma-derived therapies are used today for a wide variety of diseases and conditions, including autoimmune conditions and blood disorders, including hemophilia, an inherited bleeding disorder.

On Monday, Del Rio said it’s worrying when the president promotes COVID-19 therapies, such as hydroxychloroquine, with scant evidence of efficacy and potential harmful side effects. The FDA granted hydroxychloroquine an emergency authorization before suspending it months later after several trials showed the drug didn’t work against COVID-19 and raised the risk of heart, kidney and liver problems.

In a letter describing the emergency authorization, the chief scientist for the FDA, Denise Hinton, noted: “COVID-19 convalescent plasma should not be considered a new standard of care for the treatment of patients with COVID-19. Additional data will be forthcoming from other analyses and ongoing, well-controlled clinical trials in the coming months.”

But some worried that an emergency authorization could remove some important safety and protection measures in place and send the wrong message to the doctors and patients.

The World Health Organization on Monday cautioned that using blood plasma from COVID-19 survivors to treat other patients is still considered an experimental therapy. Still, some patients are requesting the treatment instead of agreeing to take part in clinical studies.

The Associated Press contributed to this article.

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