There is more evidence suggesting drugs touted by President Donald Trump as potential COVID-19 treatments are not effective against the virus.
Researchers studied more than 14,000 patients.
Nearly three quarters were given hydroxychloroquine while some were also treated with the antibiotic known as "Z-Pak".
The scientists found the medications did not significantly reduce death rates.
They also found patients who were given both drugs were twice as likely to suffer cardiac arrest.