* not fit to consent and unable to follow the protocol; * age \<18 years; * current tracheostomy or laryngectomy; * hypersensitivity to the active substance or to any of the excipients; * concomitant respiratory therapy such as oxygen or ventilator support. positive airway pressure for obstructive sleep apnea is permitted if treatment was established with good compliance at least 3 months before enrolment; * need for hospitalisation for any reason; * inability to safely self-administer nasal spray * any clinical contraindications, as judged by the qualified medical practitioner; * clinical signs indicative of moderate, severe or critical covid severity symptoms (as defined by fda covid-19 guidance document) * mentally or neurologically disabled patients who are considered not fit to consent to their participation in the study; * lactating, pregnant or planning to become pregnant during the study period; * diagnosed with prior covid-19 infection (\>48 hours from the time the test is reported prior to the time of screening). * no relevant comorbidity or only one comorbidity

* not fit to consent and unable to follow the protocol; * age \<18 years; * current tracheostomy or laryngectomy; * hypersensitivity to the active substance or to any of the excipients; * concomitant respiratory therapy such as oxygen or ventilator support. positive airway pressure for obstructive sleep apnea is permitted if treatment was established with good compliance at least 3 months before enrolment; * need for hospitalisation for any reason; * inability to safely self-administer nasal spray * any clinical contraindications, as judged by the qualified medical practitioner; * clinical signs indicative of moderate, severe or critical covid severity symptoms (as defined by fda covid-19 guidance document) * mentally or neurologically disabled patients who are considered not fit to consent to their participation in the study; * lactating, pregnant or planning to become pregnant during the study period; * diagnosed with prior covid-19 infection (\>48 hours from the time the test is reported prior to the time of screening). * no relevant comorbidity or only one comorbidity

not fit to consent and unable to follow the protocol; age <18 years; current tracheostomy or laryngectomy; hypersensitivity to the active substance or to any of the excipients; concomitant respiratory therapy such as oxygen or ventilator support. positive airway pressure for obstructive sleep apnea is permitted if treatment was established with good compliance at least 3 months before enrolment; need for hospitalisation for any reason; inability to safely self-administer nasal spray any clinical contraindications, as judged by the qualified medical practitioner; clinical signs indicative of moderate, severe or critical covid severity symptoms (as defined by fda covid-19 guidance document) mentally or neurologically disabled patients who are considered not fit to consent to their participation in the study; lactating, pregnant or planning to become pregnant during the study period; diagnosed with prior covid-19 infection (>48 hours from the time the test is reported prior to the time of screening). no relevant comorbidity or only one comorbidity

not fit to consent and unable to follow the protocol; age <18 years; current tracheostomy or laryngectomy; hypersensitivity to the active substance or to any of the excipients; concomitant respiratory therapy such as oxygen or ventilator support. positive airway pressure for obstructive sleep apnea is permitted if treatment was established with good compliance at least 3 months before enrolment; need for hospitalisation for any reason; inability to safely self-administer nasal spray any clinical contraindications, as judged by the qualified medical practitioner; clinical signs indicative of moderate, severe or critical covid severity symptoms (as defined by fda covid-19 guidance document) mentally or neurologically disabled patients who are considered not fit to consent to their participation in the study; lactating, pregnant or planning to become pregnant during the study period; diagnosed with prior covid-19 infection (>48 hours from the time the test is reported prior to the time of screening). no relevant comorbidity or only one comorbidity