Treating COVID-19 with Convalescent Plasma

Due to the newness and complexity of COVID-19, approved treatment methods are non-existent. While doctors and researchers are striving to develop and/or find effective ways of combatting the virus, the Food and Drug Administration (FDA) has yet to approve any specific therapy.

This has left healthcare providers in the lurch, as they have to adopt a method of trying many things and seeing what, if anything, seems to work. Many treatments don’t work at all, while the safety of using certain methods could be questionable given the unknowns.

In August, the FDA granted treatment of COVID-19 with convalescent plasma an Emergency Use Authorization. This means that while the treatment is not technically approved, it may be used in an unapproved manner due to the emergency situation at hand.

Because the potential benefits of convalescent plasma treatment may outweigh the potential risks, an Emergency Use Authorization was granted for use in COVID-19 patients.

So, what are the potential benefits, and why did this particular treatment receive special emergency authorization?

Convalescent plasma has been used in the treatment of viral infections for over 100 years, including during the influenza pandemic of 1918, H1N1, and Ebola. However, the only randomized controlled trial (RCT) that demonstrated the efficacy of convalescent plasma for the treatment of infectious disease took place over 40 years ago.

China began using convalescent plasma to treat COVID-19 patients early in the pandemic. Soon thereafter, several countries, including the United States, began conducting RCTs. Due to the circumstances, the FDA and Mayo Clinic chose to conduct retrospective, indirect evaluations of efficacy. To do so, they used Expanded Access Program (EAP) data.

Based on analysis of 4,330 patients, the FDA study concluded that plasma convalescence led to no difference in 7-day mortality between intubated patients who received high-titer plasma and those who received low-titer plasma. There was a small difference in non-intubated patients, however, with 11% of high-titer plasma patients dying within 7 days, compared to 14% of those who received low-titer plasma. Those numbers shifted to 6.3% and 11.3% in non-intubated patients younger than 80 years old.

The Mayo Clinic study reached similar conclusions, with no statistical significance being found between the high-titer and low-titer groups.

What this means is that convalescent plasma treatment for COVID-19 may be effective, but not conclusively so. The differences found could be attributed to factors that were not measured, so more studies are needed to truly determine the efficacy of this treatment method for patients with COVID-19.