Exploratory Study of Aerosol Inhalation of FB2001 for Post-exposure Prophylaxis of COVID-19 Close Contacts

Inclusion Criteria: 1. Male or female individuals aged 18-65 years. 2. COVID-19 close contacts determined by epidemiological investigation (living in the same room within 72 hours before screening with individuals having positive nucleic acid amplification test for SARS-CoV-2 ). 3. Having two consecutive negative nucleic acid tests within 72 hours before enrollment. 4. Participants of childbearing age must agree to use a highly effective method of contraception. 5. Sign the informed consent form. Exclusion Criteria: 1. Pregnant women. 2. Participants who have history of prior drug allergy or are vulnerable to allergy. 3. Participants who infected with SARS-CoV-2 within previous 6 months. 4. Fever (body temperature \> 38 ℃), frequent cough and other symptoms suggestive of COVID-19 upon screening. 5. Participants with a history of asthma or chronic obstructive pulmonary disease. 6. Participants with known history of active liver disease, acute kidney disease or chronic kidney disease. 7. Participants with known history of stroke (except cavity infarction), serious heart disease or myocardial infarction. 8. Participants with known diagnosis of Alzheimer's disease, Parkinson's disease or tumor (except for radical tumor resection). 9. Blood pressure \>180/100mmHg at screening. 10. Participated in other interventional studies within previous 6 months. 11. Uptaking CYP3A4/5 strong inducers or inhibitors (rifampicin, phenytoin, carbamazepine, St. John's wort, clarithromycin, itraconazole, ketoconazole, ritonavir, cobicistat, darunavir, atazanavir, lopinavir, nelmatevir, nefazodone, etc.). 12. Participants who need to use other anti-SARS-CoV-2 therapeutic drugs during the study period. 13. Other conditions are considered unsuitable to participate in the researcher after evaluation by the researcher.