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Convalescent plasma: ‘Flavor of the month’ or valid COVID-19 treatment?


What can we learn from expanded access?

Meanwhile, some 2,200 hospitals are participating in the expanded access program being led by the Mayo Clinic nationwide; more than 9,000 patients had received infusions at press time.

One participant is Northwell Health, a 23-hospital system that sprawls across the U.S. COVID epicenter: four of the five boroughs of New York City and Long Island.

Convalescent plasma is an in-demand therapy, said Christina Brennan, MD, vice president of clinical research at Northwell. “We get patients, family members, they say my family member is at X hospital – if it’s not being offered there, can you have them transferred?” she said in an interview.

When Northwell – through the New York Blood Bank – opened up donor registration, 800 people signed up in the first 24 hours, Dr. Brennan said. As of mid-May, 527 patients had received a transfusion.

Who’s the best donor and when should donation occur?

The Red Cross, hospitals, and independent blood banks are all soliciting donors, who can sign up at the Red Cross website. The FDA recommends that donors have a history of COVID-19 as confirmed by molecular or antibody testing, be symptom free for 14 days, have a negative follow-up molecular test, and be virus free at the time of collection. The FDA also suggests measuring a donor’s SARS-CoV-2 neutralizing antibody titers, if available, with a recommendation of at least 1:160.

But questions remain, such as whether there is a theoretical risk for antibody-dependent enhancement (ADE) of infection with SARS-CoV-2. “Antibodies to one type of coronavirus could enhance infection to another viral strain,” of coronavirus, Dr. Casadevall wrote. ADE has been observed in both severe acute respiratory syndrome (SARS) and MERS.

The other risk is that donors may still be shedding active virus. While the FDA suggests that donors are unlikely to still be infectious 14 days after infection, that is as of yet unproven. Both COVID-19 diagnostics and antibody tests have high rates of false negatives, which raises the specter that infection could be spread via the plasma donation.

Daniele Focosi, MD, PhD, from Pisa (Italy) University Hospital and colleagues raise that concern in a preprint review on convalescent plasma in COVID-19. “Although the recipient is already infected, theoretically transmission of more infectious particles could worsen clinical conditions,” they wrote, noting that “such a concern can be somewhat reduced by treatment with modern pathogen inactivation techniques.”

No evidence exists that SARS-CoV-2 can be transmitted through blood, but “we don’t know for sure,” Dr. Shoham said in an interview. A reassuring point: Even those with severe infection do not have viral RNA in their blood, he said, adding, “We don’t think there’s going to be viral transmission of this particular virus with transfusion.”

For another highly infectious pathogen, the Ebola virus, the World Health Organization recommended in 2014 that potential plasma donors wait at least 28 days after infection.

It’s also not known how long SARS-CoV-2 antibodies persist in the blood; longer viability could mean a longer donation window. Dr. Focosi noted that a previous Chinese study had shown that SARS-specific antibodies in people infected with the first SARS virus, SARS-CoV-1, persisted for 2 years.

Dr. Casadevall and Dr. Pirofski have disclosed no relevant financial relationships. Shoham has disclosed no relevant financial relationships.

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