The Food and Drug Administration has allowed more liberal remdesivir use, but 6 out of 8 major hospital systems contacted by Reuters said they were not using it for moderate cases.
The drug was authorized in May for use in patients with a severe form of the illness, after trial data showed the antiviral drug helped shorten hospital recovery time.
Several hospitals, including Sheba Medical Center at Tel Hashomer and Rambam Medical Center in Haifa, had reported they were out.
"We need leaders to make these hard decisions about distributing based on equity, not just on market-driven factors."
Findings from the analysis of its late-stage study showed that 74.4% of remdesivir-treated patients recovered by Day 14 versus 59.0% of patients receiving standard of care, the company said.
Remdesivir is in high demand after the intravenously-administered medicine helped to shorten hospital recovery times in a clinical trial.
Remdesivir is expected to be in high demand as one of the only treatments so far shown to alter the course of COVID-19.