The trial, led by Professor Robert Bals, Director of the Department of Internal Medicine V at Saarland University Medical Center and Professor of Internal Medicine at Saarland University, divided the 450 participants into two groups. The treatment group of 227 individuals used an azelastine nasal spray three times a day over a 56-day period. During that same period, the 223 participants in the control group used a placebo spray three times a day.

Bals summarized the key finding as follows: “During the observation period, 2.2% of the participants in the azelastine group became infected with SARS-CoV-2; in the placebo group, it was 6.7%—three times as many.” All infections were confirmed by PCR testing.

In addition to showing a marked reduction in coronavirus infections, the azelastine group also displayed fewer symptomatic SARS-CoV-2 infections, a lower overall number of confirmed respiratory infections, and, unexpectedly, a reduced incidence of rhinovirus infections, another major cause of respiratory illness. In the treatment group, 1.8% developed a rhinovirus infection, compared to 6.3% in the placebo group—a proportion similar to that seen for SARS-CoV-2.