For an antiviral agent to act as an effective biological barrier on nasal mucosal surface, the formulation preferably has to be maintained on the site of action for several hours, and the nasal spray dispenser can be utilized for administering the solution to the upper respiratory tract. A "first-in-man" clinical study of the nasal spray containing anti-SARS-CoV-2 antibodies derived from bovine colostrum was conducted. The study on healthy volunteers was undertaken to evaluate how long the bovine antibodies would be maintained on the nasopharyngeal surface after administration of nasal spray. In addition, the study enabled to determine which of the two concentrations of antibodies should be used in the final nasal-spray formulation. The volunteers were followed up for 4h after administration of antibody spray and sampling was done at different time-points during this period. The concentration of antibodies from patient samples was measured using ELISA analysis. In addition, as this was a "first-in-man" study any adverse events following the administration of spray were also monitored.

To test the nasal biological availability of the BioBlock® immunoglobulin preparation, 16 healthy volunteers were recruited in the phase 0 clinical trial. The study was conducted in the premises of the Ear Clinic of Tartu University Hospital. The study protocol was approved by Research Ethics Committee of the University of Tartu on March 17, 2021 (No 336/T-1). Written informed consent in accordance with the Declaration of Helsinki was obtained from each healthy volunteer. The study group was divided into two subgroups where the individuals were intranasally administered into both nostrils of BioBlock® formulation which contained either 0.1 mg/mL or 0.2 mg/mL of the colostrum immunoglobulin preparation (n=8 in both study groups). A filter paper with a volume capacity of 15 µL was placed on the medial nasal surface using surgical forceps and it was kept on nasal mucosa for 10 minutes. Following this the BioBlock was administered to the nasal cavity. The nasal mucosal sampling was done at 4 timepoints. The samples were analyzed using a Cow IgG ELISA kit.

Inclusion Criteria:

• Healthy individuals
• Age 18-80
• Have not been diagnosed with SARS-COV-2 infection (lack of positive PCR test)
• Have not been vaccinated against SARS-COV-2 infection

Exclusion Criteria:

• Pregnancy
• Serious allergic or anaphylactic reactions to medications
• Allergies to milk products
• Ear-nose-throat pathologies (anatomic and diseases)
• Immunodeficiency conditions (cancers, hematologic diseases, HIV, congenital immunodeficiency)
• Viral hepatitis A,B and C
• Upper airway infections
• Autoimmune diseases (diabetes, COPD, asthma, rhinitis, RA, psoriasis)
• Concomitant drugs - glucocorticosteroids, biologic drugs, inhalable medications