Study design
This was a prospective, randomized, double-blind, placebo-controlled dose-finding proof-of-concept study, in which azelastine nasal spray was used in 2 doses: the commercially available concentration of 0.1% and a fivefold lower concentration of 0.02%. After having given informed consent, patients tested positively for SARS-CoV-2 were examined to assess eligibility according to inclusion/non-inclusion criteria and subsequently randomized to one of the three study groups. The first administration of the nasal spray was carried out in the presence of the investigator; products were subsequently self-administered for 11 days (treatment phase). During the treatment phase, 7 visits (V1–V7) took place on days 1, 2, 3, 4, 5, 8 and 11. Samples of day 1 represent pre-treatment baseline samples. During visits, nasopharyngeal swabs were taken for quantitative PCR measurements, and investigators assessed the patient status in accordance with the WHO clinical progression scalePatient reported outcomes were documented by patient diaries and questionnaires. Therefore, during the treatment phase, patients were required to document the severity of their COVID-19 related symptoms in an electronic diary on a daily basis. On days 1, 5, 8 and 11, patients completed the standardized SF-36 questionnaire of quality of life. A summary of study activities is displayed in Table Study flow chart.