- participants diagnosed with another (non-covid-19) respiratory infection. - participants with a current tracheostomy or laryngectomy. - participants who are receiving concomitant respiratory therapy such as oxygen, positive airway pressure or ventilatory support. note: positive airway pressure for obstructive sleep apnea is permitted if the treatment was established with good compliance for at least 3 months before study enrollment. - participants with newly diagnosed illnesses that are not deemed stable by the participant's primary care physician), based on investigator assessment of medical history during screening. - participants who use intranasally dosed drugs, prescriptions or over-the-counter medications such as fluticasone. - participants who need hospitalization for reasons other than covid-19 infection. - participants who are unable to safely self-administer the nasal spray as directed. - clinical signs indicative of moderate, severe, or critical covid severity symptoms (requirement for supplemental oxygen, limitation of activities due to covid-19 symptoms). - females who are breastfeeding, pregnant, or attempting to become pregnant. - participants who have experienced symptoms of covid-19 for more than 7 days prior to randomization. - participants who have any other condition that, in the opinion of the investigator, would interfere with a participant's ability to adhere to the protocol (eg, participants who are mentally or neurologically disabled and who are considered not fit for their participation in the study), interfere with assessment of the investigational product, or compromise the safety of the participant, or the quality of the data.

- participants diagnosed with another (non-covid-19) respiratory infection. - participants with a current tracheostomy or laryngectomy. - participants who are receiving concomitant respiratory therapy such as oxygen, positive airway pressure or ventilatory support. note: positive airway pressure for obstructive sleep apnea is permitted if the treatment was established with good compliance for at least 3 months before study enrollment. - participants with newly diagnosed illnesses that are not deemed stable by the participant's primary care physician), based on investigator assessment of medical history during screening. - participants who use intranasally dosed drugs, prescriptions or over-the-counter medications such as fluticasone. - participants who need hospitalization for reasons other than covid-19 infection. - participants who are unable to safely self-administer the nasal spray as directed. - clinical signs indicative of moderate, severe, or critical covid severity symptoms (requirement for supplemental oxygen, limitation of activities due to covid-19 symptoms). - females who are breastfeeding, pregnant, or attempting to become pregnant. - participants who have experienced symptoms of covid-19 for more than 7 days prior to randomization. - participants who have any other condition that, in the opinion of the investigator, would interfere with a participant's ability to adhere to the protocol (eg, participants who are mentally or neurologically disabled and who are considered not fit for their participation in the study), interfere with assessment of the investigational product, or compromise the safety of the participant, or the quality of the data.