Since then, attempts to study the drug have been plagued by confusion. In May, The Lancet, one of the best-regarded medical journals in the world, retracted a hydroxychloroquine study last month when its data was cast into doubt. In early June, researchers on Oxford’s RECOVERY study, a large-scale, randomized study of the efficacy of several drugs in treating Covid-19 patients, reported that they had observed no benefit from hydroxychloroquine. The results were so clearly unpromising that the researchers ended the hydroxychloroquine arm of their study prematurely. Another randomized study from Shanghai Jiao Tong University found that hydroxychloroquine did not decrease mortality in Covid-19 patients. But this study was open-label, which means that both clinicians and patients knew who was receiving treatment. Both of these studies were cited prominently in the FDA’s decision to revoke the EUA.
So far, only one large-scale randomized, double-blind study of the drug’s utility has been published in a scientific journal; conducted by researchers at the University of Minnesota, the study found that hydroxychloroquine was no better than a placebo at preventing infection among people exposed to the virus, a use known as post-exposure prophylaxis.
And earlier today, the World Health Organization dropped hydroxychloroquine from its international Solidarity clinical trial of four different treatments, following the results of these other studies.
Issuing an EUA in the absence of convincing evidence is not always unjustified, Wachter says. “The FDA has this very tricky balance that it’s always weighing between speed and safety,” he says. Early in a pandemic, he adds, “it’s not unreasonable to tilt the playing field a little bit more toward speed.”
But to some observers, the hydroxychloroquine EUA seems to have been motivated by factors outside of science. “You can’t help but think that there [was] political pressure,” says Derek Lowe, a pharmaceutical expert and author of the drug discovery blog In the Pipeline. Wachter concurs. “Assuming that the president of the United States had never mentioned the drug in public, and certainly never touted its potential benefits, would that have happened?” he asks. “I’m guessing it would not have.” (An FDA representative also did not respond to a request for comment on this point.)
For Lowe, Wachter, and Nori alike, the questions raised by the FDA’s speedy issuance—and retraction—of an EUA for hydroxychloroquine raise concerns about what might happen once a Covid-19 vaccine candidate needs approval. “There are a lot of people, and I’m one of them, worried that perhaps Trump or the higher-ups in the administration will end up picking a favorite [vaccine] the way they picked hydroxychloroquine,” Lowe says. “And that would of course be a terrible idea, because we’re going to have an awful lot of data to collect about an awful lot of candidates before we start talking about which one to approve first.”
Even when data about vaccine efficacy and side effects become available, approval decisions are unlikely to be straightforward. Wachter anticipates that the FDA will have to determine whether to allow vaccines to be distributed before their long-term safety can be definitively proven and weighed against their benefits. “Do we wait three months, [given] how many people are going to get infected and how many people are going to die in those three months, or do we move faster?” he asks. “I think that’s an incredibly hard call.”
For his own part, Lowe urges caution among scientists who hope to discover the next big thing in Covid-19 treatment. “We are going to be in this for a while,” Lowe says. “So, we should take a deep breath and try to do this right. Measure twice, cut once.”
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