Small Trial Finds No Evidence That Hydroxychloroquine Works Against Covid-19

In France, hydroxychloroquine is sold by the pharmaceutical company Sanofi as Plaquénil.
In France, hydroxychloroquine is sold by the pharmaceutical company Sanofi as Plaquénil.
Image: Getty Images

A small trial from China may already throw into question whether a treatment touted as a way to save people with severe covid-19 can really work. It found no evidence that the existing drug hydroxychloroquine alone was more effective for patients hospitalized with the novel coronavirus than standard care. However, the results aren’t any more definitive than the earlier research that suggested the drug can work.

Hydroxychloroquine and its close relative chloroquine are both existing drugs, used to treat acute cases of the infectious disease malaria as well as certain autoimmune disorders like lupus. But scientists have long speculated that both drugs have a broad antiviral effect. Earlier research in the lab had specifically shown these drugs could kill the SARS virus, closely related to the new coronavirus known as SARS-CoV-2. Most recently, reports from doctors in China and France treating severe covid-19 patients reported success with using hydroxychloroquine, sometimes in combination with the antibiotic azithromycin.

Those reports prompted President Donald Trump to praise these drugs, calling for them to be deployed immediately to hospitals across the U.S. Trump’s own public health experts and outside researchers, however, have struck a more cautious tone, rightly arguing that more rigorous research is needed to test out any promising treatment for covid-19 before it could be widely used. This week, the World Health Organization announced that hydroxychloroquine/chloroquine would be among the drugs evaluated in a large, globe-spanning clinical trial of covid-19 treatments.


But given the early anecdotal success of these drugs, doctors have already started carrying out their own small, controlled clinical trials. This latest one, reported in the Journal of Zhejiang University, involved 30 patients in China that had been hospitalized with covid-19. Half were given standard care, and the other half received hydroxychloroquine for five days alongside this care. The patients also had their throats routinely swapped for the genetic presence of the virus, with a negative result indicating that the active infection had passed.

By day seven, most people in either group had negative throat swabs, with no clear advantage seen for those on hydroxychloroquine. There was also no significant difference in the amount of time it took patients in either group to stop having symptoms such as a high fever (one person’s condition in the hydroxychloroquine group worsened severely, but all had improved by the end of the trial).

The findings seem to be the first from a randomized and, importantly, controlled trial involving hydroxychloroquine. But the sample size is still very small. It also didn’t test the combination of azithromycin, which researchers theorize can have an added anti-inflammatory effect and help treat severe covid-19 cases where people are infected by bacteria along with the coronavirus.


This study, in other words, isn’t a death knell for hydroxychloroquine and chloroquine, but it may provide a clear lesson for why any experimental treatment shouldn’t be hyped too early.

Following Trump’s proclamation, people in the U.S., including doctors, are already rushing out to stockpile these drugs, which could affect their supply for patients who rely on them for their intended purpose. Tragically, one person has died after taking tablets containing chloroquine that were originally intended to treat parasitic infestations in aquariums, while that person’s wife remains in critical condition (chloroquine can easily be toxic in too high a dose).


Update 3/26 11am ET: Many in the comments asked about what other drug treatments the subjects of the study received. Lead author Jun Chen told Gizmodo via email that patients in both groups received other antivirals that were initially considered potential treatments for covid-19.

Most patients in both groups, for instance, got the flu drug umifenovir (not sold in the U.S.), and two patients in the control group took lopinavir/ritonavir, a combination therapy used typically to suppress HIV. However, he noted, these drugs also haven’t shown much if any success in subsequent trials, including in an earlier study published by his team.


Again, this study is limited in what it can tell us due to the small sample size. Though their results suggest that hydroxycholoroquine by itself doesn’t provide any added efficacy for covid-19, larger clinical trials are needed to determine effective drug therapies for covid-19.

Science writer at Gizmodo and pug aficionado elsewhere

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This article is extremely misleadingly. It was Antiviral vs Antiviral and BOTH showed promise. The “conventional” group was treated with “the use of anti-viral drugs recommended in China’s treatment guidelines like lopinavir and ritonavir” What the hell is wrong with journalist these days?