A new study conducted in human cell cultures and mouse models shows that the broad-spectrum antiviral remdesivir has a direct effect against SARS-CoV-2, the new coronavirus that causes COVID-19.

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Remdesivir may help shorten the recovery time for people hospitalized with COVID-19.

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In the race to find an effective treatment for COVID-19, the respiratory disease caused by an infection with the new coronavirus, some scientists have zeroed in on an existing broad-spectrum antiviral drug called remdesivir.

Recent research, including a preliminary report published in NEJM in May, has found that the drug — which is delivered through injections — can shorten the recovery time for people hospitalized with COVID-19.

Also in May, and based on information from similar reports, the Food and Drug Administration (FDA) issued an emergency use authorization for the administration of remdesivir in the treatment of severe forms of COVID-19.

While the drug has shown promise, much remains unknown, including whether it has a direct effect on the virus.

Now, a new study has made some headway in addressing this knowledge gap. The research comes from Vanderbilt University Medical Center (VUMC), in Nashville, TN, The University of North Carolina at Chapel Hill, and Gilead Sciences — the pharmaceutical company that initially developed remdesivir.

The team worked with human cell cultures and mouse models to find out whether the antiviral drug acted directly on SARS-CoV-2 in lung cells.

“All of the results with remdesivir have been very encouraging, even more so than we would have hoped, but it is still investigational, so it was important to directly demonstrate its activity against SARS-CoV-2 in the lab and in an animal model of disease,” explains first study author Andrea Pruijssers, Ph.D., from VUMC.

The investigators present their findings in the journal Cell Reports.

First, the researchers looked at remdesivir’s effect on human lung cells and airway epithelial cells, among other cell cultures that had been infected with SARS-CoV-2.

This experiment revealed that the drug “potently inhibits” the replication of the new coronavirus in human lung cells and airway epithelial cells.

They also tested the drug in vivo, in mice that they had infected with an adapted variant of SARS-CoV-2.

The experiments in mouse models were also promising: Remdesivir reduced the viral load in rodents treated with this drug, protecting their lung function and improving outcomes.

“This is the first rigorous demonstration of potent inhibition of SARS-CoV-2 in continuous and primary human lung cultures and the first study suggesting efficacy of [remdesivir] against SARS-CoV-2 in mice,” the researchers write in their study paper.

Yet scientists must go beyond verifying remdesivir’s action against SARS-CoV-2, the investigators point out.

Pruijssers explains that a current focus of the team is how to use the drug in combination with other treatment options to obtain the best results.

“We also are focusing on how to use remdesivir and other drugs in combinations to increase their effectiveness during COVID-19 and to be able to treat at different times of infection,” she says.

One collaborator, Dr. Mark Denison, also from VUMC, emphasizes that the current research may go some way toward preventing future outbreaks of other coronaviruses.

“We hope that will never happen, but just as we were working to characterize remdesivir over the past 6 years to be ready for a virus like SARS-CoV-2, we are working and investing now to prepare for any future coronavirus.”

– Dr. Mark Denison

“We want remdesivir and other drugs to be useful, both now and in the future,” says Dr. Denison.

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