Mortality in individuals treated with COVID-19 convalescent plasma varies with the geographic provenance of donors

In this article, experts from Mayo Clinic and other leading institutions use data from approximately 28,000 patients enrolled in the Expanded Access to Convalescent Plasma program. They evaluate their hypothesis that convalescent plasma has a higher efficacy, as defined by death within 30 days of transfusion, when the convalescent plasma donor and treated patient were in close geographic proximity.

Mayo Clinic researchers and collaborators found an association between lower mortality rates for hospitalized patients with COVID-19 and administration of near-sourced convalescent plasma likely containing antibodies specific to local variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). These data suggest convalescent plasma may be effective against new SARS-CoV-2 variants (e.g., delta variant).

Highlights of the article:

  • Early research has shown local variants may impact the effectiveness of convalescent plasma, such that antibodies contained in convalescent plasma may be most effective against specific viral strains.
  • Patients in the group receiving near-sourced convalescent plasma had a lower relative risk of death within 30 days of transfusion than patients receiving distantly sourced convalescent plasma, pooled relative risk of death was 0.73.
  • This observation of lower risk of death with near-sourced plasma was consistent across all regions of the US and persisted when controlling for other variables (e.g., patient characteristics, disease severity, and treatment methods).
  • This work has implications for the interpretation of clinical studies, the ability to develop effective COVID-19 treatments, and, potentially, for the effectiveness of COVID-19 vaccines as additional locally evolving variants continue to emerge.