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Medical research: Assessing the antiviral activity of chloroquine and hydroxychloroquine


July 22, 2020

Chloroquine and hydroxychloroquine show no notable antiviral effect against infections with SARS-CoV-2 in macaques or human lung cells according to two studies published online in Nature.

Hydroxychloroquine and chloroquine — drugs that are commonly used for the treatment of malaria — have been investigated for their potential to treat COVID-19 in more than 80 registered clinical trials. They have been shown to inhibit SARS-CoV-2 infection in cell cultures, but their effectiveness for the treatment of patients with COVID-19 has been debated.

Roger Le Grand and colleagues investigated the effects of hydroxychloroquine treatment in cynomolgus macaques, a non-human primate model of SARS-CoV-2 infection in humans. Hydroxychloroquine showed no substantial antiviral activity, regardless of the timing of treatment initiation, either before infection, soon after infection or late after infection. In addition, using this antimalarial drug in combination with azithromycin, an antibiotic, had no notable effect on virus levels in the macaques either.

In a separate study, Stefan Pöhlmann and colleagues found that chloroquine has no antiviral activity against SARS-CoV-2 in human lung cells. They explain that in previous experiments, the cells that were used to demonstrate a positive effect for chloroquine did not have an enzyme, which is normally present in lung cells, that facilitates the entry of SARS-CoV-2 into human lung cells. The authors emphasize the importance of using cell lines that mimic lung tissue in studies that assess the activity of drugs against SARS-CoV-2.

Together, these results do not support the use of hydroxychloroquine and chloroquine for the treatment of patients with COVID-19.

doi: 10.1038/s41586-020-2575-3

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