Hydroxychloroquine is Not a Cure for COVID-19, Scientists Say
By: Kathleen Guo
Hydroxychloroquine has been tested more than any other potential COVID-19 drug but has repeatedly fallen short of expectations. Although study after study has demonstrated no benefit of hydroxychloroquine for treating people with serious coronavirus infections, some people, including President Donald Trump, still insist the drug has potential. A viral video released July 27 that made the misleading assertion that hydroxychloroquine is an effective treatment for COVID-19 spread like wildfire online.
Initial hope that hydroxychloroquine was useful in fighting the coronavirus stemmed from lab tests showing that the drug inhibits the virus’s growth in kidney cells from monkeys by blocking its entry. However, it turns out that the virus does not enter human lung cells in the same way. In those initial experiments, researchers tested the drug using African green monkeys’ kidney cells, known as Vero cells. Those cells are useful for virologists because they allow growth of a wide variety of viruses, says Stefan Pöhlmann, a virologist at the German Primate Center in Göttingen.
However, the way SARS-CoV-2, the coronavirus that causes COVID-19, infects monkey kidney cells is different from the way it infects human lung cells, Pöhlmann and colleagues reported on July 22 in Nature. To infect different types of cells, the coronavirus has at least two major possible routes of entry. In one, the virus’s spike protein (the knobby structures on its surface) attaches to a specific protein on the cell membrane, and then an enzyme cuts the spike protein. The second way the virus gets inside cells is via a detour through special cellular compartments called endosomes. After attaching to a protein on the exterior of the cell, the virus is engulfed by an endosome. The endosome then fuses to the cellular membranes, releasing the virus’s genetic material, says Markus Hoffmann, a virologist also at the German Primate Center.
When Neil Schluger, a frontline doctor working with COVID-19 patients at Columbia University Medical Center in New York City first heard about hydroxychloroquine, he hoped it would work for his patients. He and colleagues prescribed the antimalarial drug for 811 of the 1,446 patients hospitalized at the medical center from March 7 to April 8. But the drug didn’t seem to help, Schluger and colleagues reported May 17 in the New England Journal of Medicine.
As a result, “we stopped giving hydroxychloroquine sometime in April,” he says. And yet the numbers of cases and deaths from COVID-19 in New York City have continued to fall. “If we’d taken away a lifesaving drug, you wouldn’t expect that to happen,” he says.