It has been an elusive goal so far -- finding a potent treatment that can beat back the new coronavirus before it grabs a hold of a patient's immune system and sends it into overdrive.

But new research suggests that more than a dozen existing drugs or drugs under development may do the trick.

Investigators tested more than 12,000 drugs in two different types of human cells infected with SARS-CoV-2. The drugs were either approved by the U.S. Food and Drug Administration or had been tested for safety in humans.

From those thousands of drugs, the researchers identified 90 that prevented SARS-CoV-2 from replicating in at least one of the human cell lines.

Of those drugs, 19 were found to work in concert with or boost the activity of remdesivir, an antiviral therapy already approved for treatment of COVID-19.

"Some of the most effective antiviral strategies are 'cocktails' in which patients are given several different drugs to combat the infection, such as those used to treat HIV infections," said study author Dr. Thomas Rogers, an adjunct assistant professor in the Department of Immunology and Microbiology at Scripps Research Institute in La Jolla, Calif.

Of the 19 drugs that showed promise, 13 demonstrated the highest potential to be used as oral COVID-19 therapies, based on factors such as potency, likely mechanism of action and safety, the researchers said.

Four of the 13 drugs -- halofantrine, nelfinavir, simeprevir and manidipine -- are already FDA-approved and the nine others are in various stages of development, according to the study published June 3 in the journal Nature Communications.

Two additional drugs heightened remdesivir's ability to suppress the virus, the study found: These two drugs were riboprine, a compound that's been tested as a preventative for nausea and surgical infection, and 10-deazaaminopterin, a derivative of the vitamin folic acid.

"While we now have effective vaccines against COVID-19, we still lack highly effective antiviral drugs that can prevent COVID-19 infections or stop them from worsening," said Peter Schultz, president and CEO of Scripps Research.

"Our results raise the possibility of a number of promising avenues for repurposing existing oral medications with efficacy against SARS-CoV-2," he said in a Scripps news release. "It is critical we proceed with the utmost rigor to determine what is safe and effective, as diligence is the most expedient path to finding new therapies that will make a difference for patients."