NIH panel finds "insufficient" data to support use of plasma for COVID-19

A panel of the US National Institutes of Health (NIH) concluded that "there are insufficient data to recommend either for or against the use of convalescent plasma for the treatment of COVID-19." The review by the COVID-19 Treatment Guidelines Panel comes shortly after the FDA issued an emergency-use authorisation (EUA) for convalescent plasma to treat hospitalised patients with COVID-19 amid concerns by some senior health officials that emerging data for the treatment were too weak.

The panel said it reviewed all available evidence from published and unpublished data on convalescent plasma for the treatment for COVID-19, including the FDA analyses that supported the EUA. Based on the review, the panel determined that convalescent plasma should not be considered standard of care for the treatment of patients with COVID-19, echoing comments made by FDA chief scientist Denise Hinton when the EUA was announced.

No survival benefit

According to the NIH panel, the analysis on which the EUA was based found no difference in seven-day survival overall between patients who received convalescent plasma with high titers of SARS-CoV-2 neutralising antibodies and those who received plasma with low titers. Results from a subset of hospitalised patients from the Mayo Clinic's Expanded Access Program (EAP) showed that among patients who were not intubated, 11% of those who received convalescent plasma with high antibody titers died within seven days of transfusion compared with 14% of those who received convalescent plasma with low antibody titers. Meanwhile, among those who were intubated, there was no difference in seven-day survival.

The NIH panel noted that "although these data suggest that convalescent plasma with high antibody titers may be beneficial in non-intubated patients, uncertainty remains about the efficacy and safety of convalescent plasma due to the lack of a randomised control group and possible confounding in the Mayo Clinic's EAP." The panel added that antibody levels in currently available COVID-19 convalescent plasma are "highly variable," while assays to determine the levels "remain limited."

Agencies at odds

Commenting on the panel's review, Anthony Fauci, director of the NIH's National Institute of Allergy and Infectious Diseases, denied that the new guidelines were a response to the FDA move. Fauci was said to have been one of the health officials that reportedly intervened as the FDA was preparing to issue the EUA for use of blood plasma in COVID-19. "The guidelines panel did not come out and criticise anyone or anything," he said, adding that "they were neutral" on the use of convalescent plasma for COVID-19.

However, Eric Topol, director of the Scripps Research Translational Institute, called it an "extraordinary moment," adding "here you have different governmental agencies that are at odds." Topol said "when you give pooled plasma, the chance that you will make a difference is very low. We don't know if this is going to work."

Topol also called on FDA Commissioner Stephen Hahn to explain why he misrepresented the data on convalescent plasma at the time the agency announced the EUA. At the time, Hahn said the treatment resulted in a 35% improvement in survival, although he later clarified "what I should have said better is that the data show a relative risk reduction not an absolute risk reduction." 

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