A 2020 study that evaluated hydroxychloroquine and azithromycin as treatments for COVID-19 infections has been retracted, as indicated by the "RETRACTED" watermark visible across all pages of the published paper.

In the study, published in the International Journal of Antimicrobial Agents and conducted from early March to March 16th, 2020, at IHU-Méditerranée Infection in Marseille, France, researchers enrolled 42 patients with confirmed COVID-19 infections. Twenty-six of the patients were assigned to receive 600 mg of hydroxychloroquine daily for 10 days, whereas 16 of the patients served as controls. Six patients in the hydroxychloroquine group were lost during follow-up, leaving 20 patients in the final treatment analysis.

Among the study participants, 16.7% of them were asymptomatic, 61.1% had upper respiratory tract infection symptoms, and 22.2% had lower respiratory tract infection symptoms. Some of the patients in the treatment group also received azithromycin (500 mg on day 1, followed by 250 mg daily for 4 days).

The researchers reported that 70% of hydroxychloroquine-treated patients were "virologically cured" by day 6 compared with 12.5% of controls. However, the study's methodology raised several concerns. The trial was nonrandomized and used an open-label design. The control group included both patients who refused treatment at the Marseille center and patients from other medical centers.

The 6 patients lost from the treatment group included three transfers to intensive care, one death, one patient leaving the hospital, and one stopping treatment as a result of nausea. The study's limitations included its small sample size, the loss of 6 patients to follow-up, limited long-term outcome tracking, and the use of control patients from different medical centers than the treatment group.