Hydroxychloroquine, which is widely used against malaria and arthritis, was given to hundreds of patients hospitalized with COVID-19 in Belgium. Thousands of others didn’t receive the drug.

Researchers examined records from 352 adults hospitalized in AZ Groeninge Hospital in Kortrijk, Belgium. All patients tested positive for COVID-19 or had results from CT scans that suggested COVID-19 was present. Patients received hydroxychloroquine alone or with azithromycin, an antibiotic. They were scanned before and after treatment.

Researchers compared the results of the record analysis with a control group of 3,533 people hospitalized across Belgium with COVID-19 from March 14, 2020, to May 24, 2020. The people didn’t receive hydroxychloroquine but did receive standard of care.

Twenty-eight days following the diagnosis of COVID-19, 59 people treated with hydroxychloroquine had died. The mortality percentage, or 16.7 percent, was lower than the 25.9 percentage in the control group.

Researchers found patients who received hydroxychloroquine were more likely to survive even after adjusting for age and other factors.

“Our study suggests that, despite the controversy surrounding its use, treatment with hydroxychloroquine and azithromycin remains a viable option,” Dr. Gert Meeus, a nephrologist with AZ Groeninge Hospital, and other researchers wrote.