Peginterferon λ for the treatment of patients admitted to hospital with COVID-19: a phase 2, placebo-controlled randomized trial.

Objectives: SARS-CoV-2 continues to circulate widely, and there is a need to find effective treatments for individuals admitted to hospital. Peginterferon λ has been shown to be effective for outpatients with COVID-19; the purpose of this randomized trial was to evaluate the efficacy among inpatients.

Methods: Individuals admitted to hospital with COVID-19 who were within 10 days of symptom onset and receiving <6 L/min of supplemental oxygen were recruited from seven sites in Canada and Brazil from November 23, 2020 until December 6, 2022. Participants were randomized to receive two doses of 180 mcg of subcutaneous peginterferon λ or placebo (at enrolment and day 5). The primary outcome was clinical status according to the WHO COVID severity scale at day 14 with the main secondary analysis being the probability of hospital discharge over time until day 28. The trial was stopped prematurely due to the changing conditions of the pandemic.

Results: Total of 97 participants were enrolled with 94 contributing outcome information. The global odds ratio of peginterferon λ leading to improved outcomes according to the WHO severity scale was 0.76 (95% CI, 0.35-1.66; p = 0.49). Clinical trajectories were similar between the peginterferon λ and placebo groups. The probability that peginterferon λ, as compared with placebo, led to a >1-day reduction in duration of hospitalization was 0.04. No safety concerns were identified.

Discussion: In this phase II, prematurely stopped randomized placebo-controlled trial of peginterferon λ for individuals hospitalized with COVID-19 infection, no apparent benefit was identified.