Hydroxychloroquine does not keep patients with common autoimmune diseases from contracting COVID-19, a new study has found. The results suggest that it will not prevent the disease in the general population, investigators say.

Apart from its role as an investigational drug against COVID-19, hydroxychloroquine has been used to suppress the immune system, relieving inflammatory symptoms in rheumatoid arthritis and systemic lupus erythematosus. Relatively small studies have shown a possible link between the drug and COVID-19 prevention, generating much discussion and hope during the pandemic.

This current study is larger than the earlier ones, drawing de-identified data from 36 health systems. Among the 159 patients found with lupus and rheumatoid arthritis, those who contracted COVID-19 were just as likely to be taking hydroxychloroquine as those who did not get COVID-19, said lead author Mendel Singer, Ph.D., MPH., from Case Western Reserve University in Cleveland.

“If hydroxychloroquine were effective in prevention, we would have seen fewer hydroxychloroquine-taking [lupus] and rheumatoid arthritis patients with COVID-19, but did not,” Singer said. “This likely means that hydroxychloroquine is not active against the SARS-CoV-2 virus in humans versus in the lab, and is unlikely to be an effective preventive antiviral for anyone.”

Their findings were published in the Annals of the Rheumatic Diseases.