Hydroxychloroquine or chloroquine is probably one of the most known drugs, that are widely used as a treatment for COVID-19. It is very well known to the general public since certain public figures and health agencies actively recommended using it, but what do we know about their effectiveness and safety?

Scientists from Switzerland and USA concluded, that most of the researches that are used as a proof for the usefulness of hydroxychloroquine with or without macrolide are based on a "small number of anecdotal experiences that have shown variable responses in uncontrolled observational analyses, and small, open-label, randomised trials that have largely been inconclusive".

The team did their own research, observing the data from 671 hospitals around the world about the patients hospitalized since December 2019 and until 14th April with the confirmed SARS-CoV-2. 14888 patients out of 96032 were in treatment groups (1868 were given chloroquine, 3783 - chloroquine with macrolide, 3016 - hydroxychloroquine, 6221 - hydroxychloroquine with macrolide); 81144 patients were in the control group. Patients who were given remdesivir and patients who received treatment with these regimens starting more than 48 h after COVID-19 diagnosis were excluded from the data.

10698 (11.1%) patients died in the hospital. After taking into consideration the confounding factors (such as age, sex, race or ethnicity, body-mass index, underlying cardiovascular disease and its risk factors, diabetes, underlying lung disease, smoking, immunosuppressed condition, and baseline disease severity) the death rate was counted. The death rate in the control group was 9.3%, 18% for the hydroxychloroquine group, 23.8% for the hydroxychloroquine with macrolide group, 16.3% for chloroquine, 22.2% for chloroquine with macrolide. The death rate was higher in every group compared to the control group.

The other important thing to notice is that patients in hydroxychloroquine and chloroquine groups had a risk of de-novo ventricular arrhythmia which was not present before hospitalization.

Researchers conclude that they weren't able to find any proof for the hydroxychloroquine effectiveness, with or without macrolide. According to Retraction Watch, the French researchers are withdrawing their article on hydroxychloroquine reducing the SARS-CoV-2 death rate.