Does chloroquine work?

President Trump has doubled down on his promotion of the drug called chloroquine.

Here’s a reality check on what it is, and whether it really could be an effective intervention against coronavirus:

What is chloroquine?

Chloroquine and its less toxic alternative, hydroxychloroquine, are widely-used antimalarial drugs,used since World War II. For decades, scientists have been exploring its antiviral properties, and the coronavirus pandemic has renewed interest in the drug.

First discovered over 85 years ago, it’s now a generic (read: incredibly cheap) drug to manufacture. For decades, scientists have been exploring its antiviral properties; it was studied as a potential treatment for HIV in the 1990s, and against SARS in 2005. That research never went anywhere, but chloroquine is once again being looked at as the coronavirus pandemic rages on.

It’s now very cheap to manufacture, and we know its side effects pretty well.

How does it work agaomst coronanvirus?

The Covid-19 virus uses a protein spike on its surface to bind to the surface of a human host cell, through a process called glycosylation. Chloroquine has shown an ability to interfere with glycosylation in viruses like SARS and prevent binding. SARS and Covid-19 are caused by the SARS-CoV and SARS-Cov-2 viruses, respectively. They share many similarities. So there’s hope chloroquine can exhibit the same effect on SARS-Cov-2.

Is it really effective?

That’s the question everyone’s trying to answer right now. Chinese doctors first used chloroquine as an experimental treatment when the outbreak first spread throughout Wuhan, and reported some success. Italian and South Korean doctors have also approved it for experimental use to treat patients. Trump’s promotion of the drug has leaned heavily on a French study of the drug on 20 participants, which is an incredibly small sample size. One study found that there seems to be some justification in its use as an experimental treatment, but concluded that much more data is needed before it could be used widely.

Is it dangerous?

It can be. According to the Mayo Clinic, there are 14 different drugs that should not be taken with chloroquine. Side effects include nausea and vomiting, cramps, headaches, blurred vision, and diarrhea. Though hydroxychloroquine is supposed to be a safer form of the drug, it can elicit the same side effects. There have been overdoses in Nigeria in the wake of Trump’s comments, and an American died after ingesting the drug in a non-pharmaceutical form.

Why Trump?

A new report from Reuters suggests Trump has personally pushed for advancing chloroquine and hydroxychloroquine as a treatment of covid-19 despite the dearth of clinical evidence to support its efficacy. His interventions have gone beyond just tweets and public comments, including instructing the CDC, FDA, and NIH “to focus on the two drugs as potential therapies” and make them widely available to patients, according to Reuters. The CDC recently posted new guidelines that, while stopping short of recommending the drugs, cites it as a possible treatment.

In spite of Trump’s remarks, National Institute of Allergy and Infectious Diseases Chief Anthony Fauci has been more cautious. “In terms of science, I don’t think we can definitively say it works,” he said in an interview with CBS. “The data are really just at best suggestive. There have been cases that show there may be an effect and there are others to show there’s no effect.”