Convalescent plasma may be another tool to help prevent coronavirus infections sparked by the omicron variant from turning severe if patients receive it soon after developing symptoms, according to data presented Tuesday.
The treatment, which contains a bounty of disease-fighting antibodies, could expand doctors’ repertoire for fighting the now-dominant variant that resists many treatments. Convalescent plasma – taken from blood donated by people who have recovered from covid-19 – could join the monoclonal antibody sotrovimab and soon-to-be authorized antiviral drugs as an important therapy for people who become ill.
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Scientists from the Johns Hopkins Bloomberg School of Public Health and Johns Hopkins University School of Medicine published findings showing that giving plasma early during the course of illness reduced hospitalization by half in a clinical trial that spanned June 2020 to October 2021. The results, published on the preprint website MedRxiv, support the early use of antibody-rich convalescent plasma to prevent hospitalization in patients not yet critically ill.
“Our findings suggest that this is another effective treatment for COVID-19 with the advantages being low cost, wide availability and rapid resilience to the evolving SARS-CoV-2,” Kelly Gebo, a co-lead author of the study and professor of medicine at the Hopkins School of Medicine, said in a statement.
The clinical trial used plasma collected before vaccines were widely available, Daniel Hanley, a professor of neurology at the Hopkins School of Medicine, said at a news briefing Tuesday. The trial concluded before omicron arrived in the United States, but researchers say the results offer hope for treating the highly transmissible variant.
Other studies have shown that plasma from people who have been both vaccinated and recovered from covid-19 contains significantly higher amounts of antibodies, making it more likely to promote an immune response against omicron, said David Sullivan, co-lead author of the study and a professor of molecular microbiology and immunology at the Hopkins School of Public Health.
And with vaccines in wide use, experts said it should be easier to collect such antibody-plentiful plasma.
“We do think that this vaccinated plasma is a way forward that will prevent hospitalizations because of the high titers,” Sullivan added.
The infrastructure to produce convalescent plasma from blood donated by people with high levels of antibodies exists widely across the United States and internationally. Because of that, the treatment could be made available relatively quickly, researchers said.
“We use blood transfusions every single day in the hospital. It is one of the most common, safest procedures performed in medicine,” said Aaron Tobian, director of the Transfusion Medicine Division at Johns Hopkins University School of Medicine. “Now we have data showing that blood transfusions of convalescent plasma reduce hospitalizations and we think everyone should be aware of it.”
The value of convalescent plasma has been controversial for much of the pandemic. Early last year, demand for the treatment skyrocketed, as physicians desperate to help patients saw it as one of the few measures that might be beneficial. But disappointing studies and a political outcry involving convalescent plasma chilled enthusiasm for the treatment.
The Trump administration pushed the therapy as an option for hospitalized patients early in the pandemic, before its effectiveness was proved. In August 2020, when the Food and Drug Administration gave emergency authorization to convalescent plasma, President Donald Trump and then-FDA commissioner Stephen Hahn sharply overstated the treatment’s effectiveness, leading to widespread criticism. In February, the FDA narrowed use of the plasma to the antibody-rich version and said it should be used early in the treatment of hospitalized patients.
Several clinical trials have raised questions about whether it worked, leading the World Health Organization this month to recommend against giving the treatment to covid-19 patients.
But more recent data appears to suggest giving the right kind of plasma at the right time can prove helpful.
The renewed interest in convalescent plasma to treat covid-19 reflects new data and a dearth of treatments to counter the omicron variant, which accounted for more than 73% of new covid cases in the United States during the week ending Dec. 18.
Most versions of another treatment known as monoclonal antibodies, which are designed to keep patients out of the hospital, don’t appear to work against omicron.
The Pfizer-BioNTech and Moderna vaccines offer protection from serious disease and hospitalization resulting from omicron, especially if people get a third dose.
Pills to treat covid from Merck and Pfizer, which may be authorized by the FDA as soon as this week, offer help but come with limitations: The Merck drug is less effective than expected from preliminary trial results, and the Pfizer medication will be in short supply for some time.
Based partly on the Johns Hopkins trial on convalescent plasma, several scientists are petitioning the FDA to expand the authorization for convalescent plasma to include outpatients. Currently, plasma is authorized only for hospitalized patients – who are far sicker and less likely to benefit, scientists say.
“Extending the [emergency use authorization] to the outpatient space would immediately give physicians a safe and desperately needed tool to combat the rapidly escaping omicron variant and immediately fill the gap created by the loss of activity” of monoclonal antibodies, the scientists said in an email explaining the letter to the FDA.
“The key thing is omicron,” Arturo Casadevall, a co-author of the letter to the FDA and of the study published Tuesday, said in an interview.
The elimination of most monoclonal antibodies “has taken out a main line of defense,” said Casadevall, chair of microbiology and immunology and infectious diseases at the Hopkins School of Public Health. He said many hospitals have established clinics to administer monoclonal antibodies and that those facilities can be used for convalescent plasma.
The treatment may also play a major role internationally, if the WHO reconsiders its stance on using plasma to treat covid-19 patients who have not yet developed severe illness from the virus.
“This is a big deal for the developing world,” said Alfred Sommer, an epidemiologist and former dean of the Hopkins School of Public Health.
In low-income nations, convalescent plasma may be the most widely available treatment option because it is relatively inexpensive and the infrastructure to produce and distribute it to patients exists.
“This is a tool to lower mortality,” Sommer said, explaining how countries such as South Africa routinely collect blood from patients and can quickly tell whether the plasma is rich in antibodies. “They could do this tomorrow.”
Liise-anne Pirofski, a professor of medicine, microbiology and immunology at Albert Einstein College of Medicine who signed the letter to the FDA, said expanding use of convalescent plasma to include outpatients is “critical, a matter of national security” to help beat back the omicron surge.
A federal official who spoke on the condition of anonymity because he was not authorized to discuss the issue said he expected the FDA to seriously consider allowing convalescent plasma to be administered to outpatients.
Still, some infectious-disease experts remain skeptical.
Jeanne Marrazzo, director of infectious diseases at the University of Alabama at Birmingham, said she will be cautious in accepting the new finding on convalescent plasma “in the wake of prior studies that have failed to show benefit. The practicalities of using it as widespread therapy are also daunting.”
But the study authors said their findings indicate convalescent plasma may be especially useful when other therapies are in short supply.
“As the changing, often unpredictable landscape of the COVID-19 pandemic demands multiple treatment options – especially in low- and middle-income nations where front line therapies, such as vaccines and monoclonal antibodies, may not be readily available – our study provides solid evidence that antibody-rich convalescent plasma should be part of the outpatient arsenal,” Sullivan said.
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The Washington Post’s Frances Stead Sellers and Paulina Villegas contributed to this report.
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