A new study by researchers of UC San Francisco has found that azithromycin (Zithromax) was no more effective than a placebo in preventing COVID-19 among non-hospitalized patients, according to Medical Xpress.

The study, published July 16 in the journal of the American Medical Association, also found that the drug may increase the risk of hospitalization, despite widespread use of the antibiotic for the coronavirus.

Lead author Dr. Catherine Oldenburg said, “These findings do not support the routine use of azithromycin for outpatient SARS-CoV-2 infection.” SARS-CoV-2 causes COVID-19 infection.

Dr. Oldenburg is an assistant professor with the UCSF Proctor Foundation.

Azithromycin is one of the broad-spectrum antibiotics used widely as a treatment for COVID-19 in the United States and the rest of the world.

“The hypothesis is that it has anti-inflammatory properties that may help prevent progression if treated early in the disease,” Dr. Oldenburg explained. “We did not find this to be the case.”

The study, conducted in collaboration with Stanford University, looked at more than 260 participants who all tested positive for COVID-19 within seven days before entering the study. Of those, 171 received a single oral dose of 1.2 gram azithromycin and 92 received a placebo.

On day 14 of the study, 50% of the participants remained symptom-free in both groups. However, by day 21, five participants who were in the azithromycin group had been hospitalized with severe COVID-19 symptoms. None of the placebo group had been hospitalized.

The authors concluded that treatment with a single dose of azithromycin compared to placebo did not result in a greater likelihood of being symptom-free, according to Medical Xpress.

Dr. Oldenburg said, “Most of the trials done so far with azithromycin have focused on hospitalized patients with pretty severe disease. Our paper is one of the first placebo-controlled studies showing no role for azithromycin in outpatients.”