Why are there so few drugs to treat viruses?

“There just aren’t that many different ways we can think of to attack viruses.”

This is according to Associate Professor Stuart Ralph, Acting Head of the Department of Biochemistry and Molecular Biology in the School of Biomedical Sciences at the University of Melbourne.

“We’ve got lots and lots of drugs for parasites and bacteria, which have lots of potentially susceptible targets, but in the case of viruses – there aren’t that many things that they actually do.

“So we’re limited to a handful, maybe only a dozen, discrete processes... that would cause the virus to either stop replicating or stop our bodies getting sick because they’ve got virus inside them.”

Dr Craig Morton is a Senior Research Fellow, based at the Bio21 Molecular Science & Biotechnology Institute at the University of Melbourne.

He says “In the case of COVID-19, [the drugs] remdesivir and dexamethasone have both been shown to have significant impacts on medical outcomes.”

“Remdesivir is a drug that targets viral replication. It wasn’t designed for COVID-19 but appears to work. Dexamethasone is an immune system modulator that actually turns your immune system down slightly. In the very sick patients that seems to be a clinically extremely useful thing to do.

“By repurposing existing drugs, you can rapidly get from having no possible treatment to having at least some way of mitigating the infection and improving the outcome of patients.”

Dr Morton explains that if you’re starting from scratch, finding a brand new compound, it traditionally takes three to five years of lab research before you get to a point of understanding the chemistry of the potential drugs.

Then, the process of testing in people takes normally five to 10 years and costs hundreds of millions of dollars.

“At the moment, we know a lot more than we did six months ago, but we’re not able to say when we’ll have drugs that work, when we’ll have a vaccine that is clinically effective,” Dr Morton says.

“Drugs for the man in the street to make sure that they don’t get sick? I think they’re still a long way off.”

Episode recorded: July 21, 2020.

Interviewer: Dr Andi Horvath.

Producer, audio engineer, editor: Chris Hatzis.

Co-production: Silvi Vann-Wall & Dr Andi Horvath.

Banner: Getty Images.