On Tuesday, the Japanese government announced it will begin clinical trials to test treatments for the deadly new coronavirus that’s engulfed China and spread to over two dozen countries. Rather than new drugs, they’ll be studying existing medications already used to treat HIV and other viral diseases. But why exactly are researchers hopeful that these drugs can be repurposed for the new coronavirus, and how likely are they to work?
The new coronavirus, recently named SARS-CoV-2 due to its close genetic ties to the SARS coronavirus, is made out of RNA. Other RNA viruses include the ones that cause Ebola, hepatitis C, and yes, HIV/AIDS.
RNA viruses come in all shapes and sizes, and those that infect humans can do so in different ways. But many of the drugs that go after HIV and the hepatitis C virus broadly target weaknesses found in all sorts of viruses. The approved hepatitis C drug ribavirin, for instance, interferes with something called the RNA-dependent RNA polymerase, an enzyme essential for many viruses—including coronaviruses—to produce more of themselves inside a cell. HIV drugs like lopinavir inhibit other enzymes that allow viruses to break down certain proteins, which cripples their ability to infect cells and replicate.
Broad antiviral drugs like lopinavir should be able to work against SARS-CoV-2, scientists theorize. And there’s already some circumstantial evidence they do. Some of these drugs have been successfully tested out for SARS and MERS, for instance, two other nasty coronaviruses that have emerged in recent years.
In January, the Chinese government announced a trial of 41 patients in Wuhan that would use a combination therapy of lopinavir and another HIV drug, ritonavir. In February, the Chinese government also began a trial using an experimental drug that’s been tested out for Ebola, called remdesivir.
Remdesivir has already been deployed during this outbreak, with seemingly impressive results so far. Last month, the first documented U.S. patient with the virus was treated with remdesivir, following a week of worsening symptoms that had developed into full-blown pneumonia. Within a day of receiving the drug through an IV, though, the man’s symptoms started to improve, and he was eventually released from the hospital.
But one case does not a surefire treatment make. And even if remdesivir or other drugs do prove effective against SARS-CoV-2, they’ll only play a small part in stopping this current outbreak from getting worse. Most cases of COVID-19 (the official name of the disease caused by SARS-COV-2) are still mild and won’t be helped much by antiviral drugs. In terms of preventing the next pandemic, it’s more important to keep people from getting the virus at all, rather than finding drugs to treat them once they do.