(CNN) -- The US Food and Drug Administration issued an emergency use authorization for the use of convalescent plasma to treat Covid-19 on Sunday, saying the "known and potential benefits of the product outweigh the known and potential risks of the product."
The FDA said more than 70,000 patients had been treated convalescent plasma, made using the blood of people who have recovered from coronavirus infections.
"Today I am pleased to make a truly historic announcement in our battle against the China virus that will save countless lives," President Trump said at a White House briefing. "Today's action will dramatically increase access to this treatment."
Last week, Trump accused some health officials of playing politics regarding an EUA for convalescent plasma. When asked about the FDA not having granted an EUA, Trump said the reason was political.
On Sunday, a source who is close to the White House Coronavirus Task Force told CNN the FDA had reviewed additional data to inform its impending EUA decision. This official has not personally reviewed the data. They added the FDA is under no obligation to consult anyone outside the agency about its decision.
Convalescent plasma is taken from the blood of people who have recovered from Covid-19. At the end of March, the FDA set up a pathway for scientists to try convalescent plasma with patients and study its impact. It has already been used to treat more than 60,000 Covid-19 patients.
However, like blood, convalescent plasma is in limited supply and must come from donors. And while there are promising signals from some studies, there is not yet randomized clinical trial data on convalescent plasma to treat Covid-19. Some of those trials are underway.
Impact of an EUA
The New York Times reported last week an FDA emergency use authorization for blood plasma to treat Covid-19 was on hold after NIH officials intervened. The hold came after a group of federal health officials -- including National Institutes of Health Director Dr. Francis Collins, National Institute of Allergy and Infectious Diseases Director Dr. Anthony Fauci and Dr. H. Clifford Lane, NIAID deputy director -- stepped in to argue the emerging data on the treatment was too weak, the Times reported Wednesday, citing two senior administration sources.
In a response to CNN, Dr. Anand Shah, FDA's deputy commissioner for medical and scientific affairs, said he couldn't comment but suggested the NIH was out of line.
"In general, NIH is not involved in the decision-making process at the FDA and does not have the entirety of confidential data the FDA uses to make these regulatory decisions," Shah said in a statement sent to CNN.
"We take seriously our mandate to follow the data and science on the review of medical products to prevent or treat COVID-19 based on the agency's established legal and regulatory standards," Shah added, saying the FDA appreciated the work of NIH and would collaborate with its sister agency.
A senior administration official told CNN's Jim Acosta on Sunday the expected emergency use authorization announcement is an important development.
"If you're one of the 35 people out of a hundred who survive severe COVID symptoms because of convalescent plasma, this is certainly a breakthrough," the official said.
"And it's certainly an advancement that over a 5 month period during a pandemic we've got safety data based on 70,000 COVID patients treated with convalescent plasma," the official added.
Ben Corb, public affairs director for the American Society for Biochemistry and Molecular Biology, said in a statement the President was showing an "unwillingness" to listen to medical experts, and that "breakthroughs require the collection of data" to ensure safety and efficacy of treatments.
"This process is necessary to ensure our safety, and to ensure that a treatment isn't worse than the disease," Corb's statement read. "I am deeply concerned by this action, and concerned about the timing."
Demand for plasma 'exceeded anyone's expectation'
Emergency use authorization from the FDA does not require the same level of evidence as full FDA approval, but it can have a significant effect on demand and use of a treatment during a public health emergency.
Dr. James Musser, chair of the Department of Pathology and Genomic Medicine at Houston Methodist, said an emergency use authorization could simplify giving convalescent plasma to Covid-19 patients.
"If they do issue an EUA, my opinion is that that is a good thing for patients going forward," said Musser, who has studied convalescent plasma in Covid-19 patients. "But once again, that is really going to depend up on the parameters of the EUA."
An EUA, which could open the treatment to more patients, could also have the effect of limiting enrollment in clinical trials that determine whether it's effective.
On Thursday, Dr. Janet Woodcock, director of the FDA's Center for Drug Evaluation and Research, said that doctors have treated so many Covid-19 patients with convalescent plasma, it has been difficult to figure out if the treatment works.
"The problem with convalescent plasma is the great enthusiasm about it," Woodcock said in an online conversation about the latest science behind monoclonal antibody treatments and convalescent plasma. "It exceeded anyone's expectation as far as the demand."
Woodcock, who has shifted to lead therapeutic efforts under the Trump administration's Operation Warp Speed, said plasma has shown some promise in early studies, but said Thursday there is still not yet enough evidence that it works.
Her team counted 162 prospective studies and several more observational studies, but she said only six met the standard that could produce actionable results. There is no randomized clinical trial data yet, she said, but some of those trials are ongoing.
"We continue to have hints that this is an effective treatment in this particular virus," Woodcock said, adding that the NIH will initiate or boost additional trials to find out for sure, she said.
Even if this approach does work, convalescent plasma has limitations.
"There's a limited donor pool -- it goes away as an epidemic wanes," Woodcock said. "It is not a standardized intervention and requires a blood type match for administration, which can be problematic in many settings."
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