There’s been a lot of hype around this drug’s potential for treating COVID-19. In May, Donald Trump claimed that he was taking hydroxychloroquine to protect himself from the coronavirus (he’s since said that he’s finished his course of treatment). But so far, high-quality evidence for its effects are lacking.


Hydroxychloroquine has been around for 65 years, first as a treatment for malaria, and more recently for autoimmune diseases such as lupus and rheumatoid arthritis.

Lab experiments over the past few decades have shown that hydroxychloroquine and the related drug chloroquine can also block the action of many different viruses, including HIV, influenza, Ebola and, most recently, the SARS-CoV-2 coronavirus.

The drugs prevent the viruses from releasing their genetic material into human cells, so the viruses are unable to replicate and start an infection.

Because of these antiviral properties, many scientists hoped that hydroxychloroquine could be used to treat or prevent COVID-19. But there’s a large gap between how drugs work in the lab and how they work in people, and hydroxychloroquine hasn’t previously passed any clinical trials (studies that involve patients) for other viruses.

Since COVID-19 first began to spread, scientists have been carrying out clinical trials with hydroxychloroquine and chloroquine, giving them to patients with COVID-19 and comparing the outcomes with COVID-19 patients who haven’t been given the treatment.

U.S. President Donald Trump receives a briefing on the 2020 hurricane season in the Oval Office May 28, 2020 in Washington, DC. (Photo by Doug MIlls-Pool/Getty Images)
US President Donald Trump claims to have taken hydroxychloroquine to protect himself from the coronavirus © Doug MIlls-Pool/Getty Images

So far, there’s no conclusive evidence that hydroxychloroquine or chloroquine can effectively prevent or treat COVID-19.

In June 2020, the UK’s RECOVERY trial – one of the world’s largest, involving over 11,000 patients – dropped hydroxychloroquine from the trial after concluding that there was no evidence for the drug's benefit in COVID-19 patients.

There are still over 100 other clinical trials around the world looking at hydroxychloroquine, and it’s possible that in some patients the drug could be helpful, but the signs aren’t looking good.

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Jeremy Rossman is a Senior Lecturer in Virology and President of Research-Aid Networks, University of Kent. His research focuses on the process of infectious disease outbreaks, and he has contributed to studies published in journals including PLoS Pathogens, Bioinformatics and Cell.