1. The subject has been enrolled in a study with niclosamide in the previous 6 months. 2. The subject is allergic to niclosamide or history of significant adverse reaction to niclosamide or related compounds, or to any of the excipient used. 3. The subject has an underlying condition that may interfere with intranasal administration of the investigational medicinal product (IMP), for example chronic ulcer(s) in the nose. 4. The subject has an acute or chronic condition that, as judged by the investigator, would jeopardize the safety of the participant. 5. The subject has a condition the investigator believes would interfere with the ability to provide consent, or comply with study instructions, or that might confound the interpretation of the study results. 6. 6. Subjects with symptoms suggesting engagement of the lower respiratory tract or a systemic engagement such as cough, feeling feverish, chills, shivering, feeling hot, low energy, tiredness, body aches and pains, fatigue, shortness of breath, loss of appetite, nausea, vomiting, or diarrhea (to be entered in the FDA COVID-19 questionnaire), or other symptoms not mentioned in inclusion criteria 5. 7. The subject has an active or acute infection other than SARS-CoV-2. 8. The subject has used other investigational products the month prior to Day 1. 9. Antiviral medications and approved or experimental medications targeting COVID-19. 10. Another member of the same household recruited to this study.

1. The subject has been enrolled in a study with niclosamide in the previous 6 months. 2. The subject is allergic to niclosamide or history of significant adverse reaction to niclosamide or related compounds, or to any of the excipient used. 3. The subject has an underlying condition that may interfere with intranasal administration of the investigational medicinal product (IMP), for example chronic ulcer(s) in the nose. 4. The subject has an acute or chronic condition that, as judged by the investigator, would jeopardize the safety of the participant. 5. The subject has a condition the investigator believes would interfere with the ability to provide consent, or comply with study instructions, or that might confound the interpretation of the study results. 6. 6. Subjects with symptoms suggesting engagement of the lower respiratory tract or a systemic engagement such as cough, feeling feverish, chills, shivering, feeling hot, low energy, tiredness, body aches and pains, fatigue, shortness of breath, loss of appetite, nausea, vomiting, or diarrhea (to be entered in the FDA COVID-19 questionnaire), or other symptoms not mentioned in inclusion criteria 5. 7. The subject has an active or acute infection other than SARS-CoV-2. 8. The subject has used other investigational products the month prior to Day 1. 9. Antiviral medications and approved or experimental medications targeting COVID-19. 10. Another member of the same household recruited to this study.