NOEL KING, HOST:

All right. Continuing now our coverage of the virus. There is no confirmed treatment for COVID-19, but President Trump has repeatedly said that there are drugs that could be effective. One of them is called hydroxychloroquine. It's used to treat malaria. It's often prescribed to people who have lupus or rheumatoid arthritis. And while it's not yet clear whether the drug will be useful for COVID-19, President Trump is urging people to consider using it now.

(SOUNDBITE OF ARCHIVED RECORDING)

PRESIDENT DONALD TRUMP: And some people say, let's go to a laboratory. Let's test it for a couple of years, and then - no, I got - we got people dying in this country and all over the world right now, not in a couple of years. They're dying - as we speak, there are people dying.

KING: Katherine Seley-Radtke is a medicinal chemist at the University of Maryland, Baltimore County. She specializes in antiviral drug research, including coronaviruses. And she's with me now on Skype.

Good morning, Katherine.

KATHERINE SELEY-RADTKE: Good morning.

KING: What do we know about using hydroxychloroquine as a treatment for COVID-19?

SELEY-RADTKE: Well, hydroxychloroquine has been shown to have no effect, actually, on reducing viral load, so it doesn't cure the virus. How it works tends to be in terms of the cytokine storm or the inflammatory response that our body starts in response to getting the virus.

And, in fact, a number of years ago, after the first two coronaviruses came out - the SARS and then the MERS strain of coronavirus - there were animal studies that showed that while the initial testing in the test tube or in vitro testing showed some promise, the actual animal testing showed no efficacy whatsoever in terms of reducing the viral replication.

KING: OK. What further research do you think is needed at this point to say this drug either works or it doesn't or it works to some extent? And how long does it - is it going to take?

SELEY-RADTKE: So as you may or may not be aware, there have been a couple very small trials that - from France and another from China that were reported in the last couple weeks. However, those results were very inconclusive, and, in fact, one of the papers from France has now been disparaged by the journal itself. However, there are a number of clinical trials that are starting or have already started recently in the United States and other countries to really look at how this drug works and whether or not it's being useful.

Part of the problem is we have a lot of anecdotal information that many people are relying on rather than relying on the science. And we really need to have these proper clinical trials with proper controls so that we can find out whether or not this is working at all. And many of the people who have taken this have said they don't know if they - if it helped them or not.

KING: They don't know if it helped them or not. OK. A last question for you, Katherine - people are dying of COVID-19 every, and there may be some who think, I would just like to go ahead and try it. What should those people know about the side effects of hydroxychloroquine?

SELEY-RADTKE: Well, as the FDA put in their guidance that they released the other day when they decided to approve this for emergency use, the - some of the side effects are very severe and involve heart arrhythmias. And because part of the infection occurs in - around the heart, people with heart problems can be severely affected. And many people who may not be aware that they have heart problems - if they're not under a doctor's care, they could have a heart attack and die. In addition, there are other side effects that involve destroying the retina in the eye. And so this is one of the reasons it's really important that a person who thinks that they want - that they should take it should see a doctor first. And, in fact, the FDA has mandated that anybody who wants to go on this should have an EKG first just to be sure that they aren't going to have any issues with heart problems.

KING: Katherine Seley-Radtke, the incoming president of the International Society for Antiviral Research, thank you so much for helping clear some of this up.

SELEY-RADTKE: No problem. Transcript provided by NPR, Copyright NPR.