The National Institute of Allergy and Infectious Diseases has stopped enrolling severely ill COVID-19 patients in a phase 3 trial of Merck’s Rebif (interferon beta-1a) with Gilead Sciences’ remdesivir because of serious adverse events.

An interim review of safety data found more adverse events among patients on high-flow oxygen/non-invasive mechanical ventilation who received Rebif vs. those who did not receive the drug.

There were no concerns among patients who had less severe COVID-19, and the trial will continue to enroll patients on low-flow oxygen and those not requiring supplemental oxygen.