Convalescent Plasma Antibody Levels and the Risk of Death from Covid-19

N Engl J Med. 2021 Mar 18;384(11):1015-1027. doi: 10.1056/NEJMoa2031893. Epub 2021 Jan 13.

Abstract

Background: Convalescent plasma has been widely used to treat coronavirus disease 2019 (Covid-19) under the presumption that such plasma contains potentially therapeutic antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that can be passively transferred to the plasma recipient. Whether convalescent plasma with high antibody levels rather than low antibody levels is associated with a lower risk of death is unknown.

Methods: In a retrospective study based on a U.S. national registry, we determined the anti-SARS-CoV-2 IgG antibody levels in convalescent plasma used to treat hospitalized adults with Covid-19. The primary outcome was death within 30 days after plasma transfusion. Patients who were enrolled through July 4, 2020, and for whom data on anti-SARS-CoV-2 antibody levels in plasma transfusions and on 30-day mortality were available were included in the analysis.

Results: Of the 3082 patients included in this analysis, death within 30 days after plasma transfusion occurred in 115 of 515 patients (22.3%) in the high-titer group, 549 of 2006 patients (27.4%) in the medium-titer group, and 166 of 561 patients (29.6%) in the low-titer group. The association of anti-SARS-CoV-2 antibody levels with the risk of death from Covid-19 was moderated by mechanical ventilation status. A lower risk of death within 30 days in the high-titer group than in the low-titer group was observed among patients who had not received mechanical ventilation before transfusion (relative risk, 0.66; 95% confidence interval [CI], 0.48 to 0.91), and no effect on the risk of death was observed among patients who had received mechanical ventilation (relative risk, 1.02; 95% CI, 0.78 to 1.32).

Conclusions: Among patients hospitalized with Covid-19 who were not receiving mechanical ventilation, transfusion of plasma with higher anti-SARS-CoV-2 IgG antibody levels was associated with a lower risk of death than transfusion of plasma with lower antibody levels. (Funded by the Department of Health and Human Services and others; ClinicalTrials.gov number, NCT04338360.).

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Antibodies, Viral / blood*
  • COVID-19 / immunology
  • COVID-19 / mortality
  • COVID-19 / therapy*
  • Female
  • Hospitalization
  • Humans
  • Immunization, Passive
  • Immunoglobulin G / blood
  • Male
  • Middle Aged
  • Registries
  • Respiration, Artificial
  • Retrospective Studies
  • Risk Factors
  • SARS-CoV-2 / immunology*
  • Time-to-Treatment
  • United States / epidemiology
  • Young Adult

Substances

  • Antibodies, Viral
  • Immunoglobulin G

Supplementary concepts

  • COVID-19 serotherapy

Associated data

  • ClinicalTrials.gov/NCT04338360