Casirivimab and Imdevimab for the Treatment of Hospitalized Patients with COVID-19

the COVID-19 Phase 2/3 Hospitalized Trial Team

Research output: Contribution to journalArticlepeer-review

24 Scopus citations


BACKGROUND: The open-label RECOVERY study reported improved survival in hospitalized, SARS-CoV-2 seronegative patients treated with casirivimab and imdevimab (CAS + IMD).

METHODS: In this phase 1/2/3, double-blind, placebo-controlled trial conducted prior to widespread circulation of Delta and Omicron, hospitalized COVID-19 patients were randomized (1:1:1) to 2.4 g or 8.0 g CAS + IMD or placebo, and characterized at baseline for viral load and SARS-CoV-2 serostatus.

RESULTS: In total, 1336 patients on low-flow or no supplemental (low-flow/no) oxygen were treated. The primary endpoint was met in seronegative patients, the least-squares mean difference (CAS + IMD versus placebo) for time-weighted average change from baseline in viral load through day 7 was -0.28 log10 copies/mL (95% confidence interval [CI], -.51 to -.05; P = .0172). The primary clinical analysis of death or mechanical ventilation from day 6 to 29 in patients with high viral load had a strong positive trend but did not reach significance. CAS + IMD numerically reduced all-cause mortality in seronegative patients through day 29 (relative risk reduction, 55.6%; 95% CI, 24.2%-74.0%). No safety concerns were noted.

CONCLUSIONS: In hospitalized COVID-19 patients on low-flow/no oxygen, CAS + IMD reduced viral load and likely improves clinical outcomes in the overall population, with the benefit driven by seronegative patients, and no harm observed in seropositive patients.


Original languageEnglish (US)
Pages (from-to)23-34
Number of pages12
JournalJournal of Infectious Diseases
Issue number1
StatePublished - Jan 1 2023


  • COVID-19
  • SARS-CoV-2
  • coronavirus
  • hospitalized
  • monoclonal antibody
  • COVID-19 Drug Treatment
  • Double-Blind Method
  • Humans

ASJC Scopus subject areas

  • Medicine(all)


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