A Study to Assess the Efficacy of HH-120 Nasal Spray for Prevention of SARS-CoV-2 Infection in Adult Close Contacts of Individuals Infected With SARS-CoV-2

Inclusion Criteria: * Participants aged 18 to 65 years. * Participants who have close contact with a SARS-CoV-2 infected individual (index case) are required to be randomized within 72 hours upon close contact. * Willing and able to provide written informed consent, or with a legal representative who can provide informed consent. Exclusion Criteria: * Have a history of severe allergy or hyper-sensitivity to inhaled allergen. * Pregnant or breastfeeding women. * Have participated, within the last 180 days prior to the screening, in a clinical study involving an investigational intervention of SARS-CoV-2 neutralizing antibody. * Have other conditions not suitable for the study per investigator's discretion.