Objective. To assess the clinical efficacy and safety of remdesivir in hospitalized adults with laboratory-confirmed COVID-19 and with evidence of lower respiratory tract involvement.
Design. Double-blinded, randomized, placebo-controlled, multicenter trial.
Setting and participants. Enrollment for the study took place between February 21, 2020, and April 19, 2020, at 60 trial sites and 13 subsites in the United States, Denmark, the United Kingdom, Greece, Germany, Korea, Mexico, Spain, Japan, and Singapore. Study participants included patients aged ≥ 18 years who were hospitalized and had laboratory-confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, as determined by a positive reverse transcription polymerase chain reaction assay on a respiratory specimen. Participants had evidence of lower respiratory tract infection at the time of enrollment; this was defined as radiographic infiltrates by imaging study, peripheral oxygen saturation (SpO2) ≤ 94% on room air, or requiring supplemental oxygen, mechanical ventilation, or extracorporeal membrane oxygenation (ECMO). Exclusion criteria for study participation included abnormal liver enzymes (alanine aminotransferase, aspartate aminotransferase) more than 5 times the upper limit of normal range; impaired renal function or need for hemodialysis or hemofiltration; pregnancy or breastfeeding; or anticipated hospital discharge or transfer to another hospital within 72 hours of enrollment.
Intervention. Participants were randomized in a 1:1 ratio to the remdesivir group or the placebo group and were administered either intravenous infusions of remdesivir (200-mg loading dose on day 1, followed by a 100-mg maintenance dose daily on days 2 through 10, or until hospital discharge or death) or placebo for up to 10 days. Blinding was maintained by masking infusions with an opaque bag and tubing. Randomization was stratified by study site and disease severity at enrollment. Supportive care was delivered to all participants according to the standard of care at each trial site hospital. Clinical status, determined using an 8-category ordinal scale and the National Early Warning Score, was assessed daily for each participant while hospitalized (day 1 through day 29).
Blood samples for safety laboratory tests were collected, and oropharyngeal or nasopharyngeal swab testing was performed for viral RNA detection and quantification on days 1, 3, 5, 8, and 11. All serious adverse events (AEs) and grade 3/4 AEs that represented an increase in severity from day 1 and any grade 2 or higher suspected drug-related hypersensitivity reactions associated with the study drug or placebo administration were recorded.
Main outcome measures. The primary endpoint measure of this study was time to recovery, defined as the first day during the 28 days after enrollment on which a participant satisfied category 1 (ie, not hospitalized, no limitations of activities), 2 (ie, not hospitalized, limitation of activities, home oxygen requirement, or both), or 3 (ie, hospitalized, not requiring supplemental oxygen and no longer requiring ongoing medical care; hospitalization was extended for infection-control reason) on the 8-category ordinal scale. Secondary outcomes included all-cause mortality at 14 and 28 days after enrollment and grade 3/4 AEs and serious AEs that occurred during trial participation. Analysis of the primary outcome was performed using a log-rank test of the time to recovery comparing remdesivir with placebo group, stratified by disease severity.
The study’s primary outcome was initially defined as a difference in clinical status as ascertained by the 8-category ordinal scale between groups of participants who were administered remdesivir versus placebo on day 15. Because of new knowledge gained external to the study about a more protracted COVID-19 clinical course than previously recognized, a change in primary outcome to time to recovery was proposed by trial statisticians, who were unaware of treatment assignments (72 participants had been enrolled) or outcome data (no interim data) on March 22, 2020, with subsequent amendment approval on April 2, 2020. On April 27, 2020, the Data and Safety Monitoring Board (DSMB) reviewed the interim study analysis (with data cutoff date of April 22, 2020) and recommended the report and mortality data to be provided to trial team members from the National Institute of Allergy and Infectious Diseases; these findings were subsequently made public.