Following the national dynamic zero-COVID strategy adjustment, the utilization of broad-spectrum nasal neutralizing antibodies may offer an alternative approach to controlling the outbreak of Omicron variants between late 2022 and early 2023 in China. This study involved an investigator-initiated trial (IIT) to assess the pharmacokinetic, safety and efficacy of the F61 nasal spray. A total of 2,008 participants were randomly assigned to receive F61 nasal spray (24 mg/0.8 mL/dose) or normal saline (0.8 mL/dose) and 1336 completed the follow-up in the IIT. Minimal absorption of F61 antibody into the bloodstream was detected in individuals receiving F61 nasal spray for seven consecutive days. No treatment-emergent adverse reactions of grade 3 severity or higher were reported. In the one-dose cohort, the 7-day cumulative SARS-CoV-2 infection rate was 79.0% in the F61 group and 82.6% in the placebo group, whereas, in the multiple-dose (once daily for 7 consecutive days) cohort, the rates were 6.55% in the F61 group and 23.83% in the placebo group. The laboratory-confirmed efficacy of F61 was 3.78% (-3.74%-10.75%) in the one-dose cohort and 72.19% (57.33%-81.87%) in the multiple-dose cohort. In the real-world study, 60,225 volunteers in four different regions were administered the F61 nasal spray based on the subject's wishes, over 90% efficacy rate was observed against different Omicron variants. The F61 nasal spray, with its favourable safety profile, could be a promising prophylactic monoclonal antibody against SARS-CoV-2 VOCs.
Keywords: F61; SARS-CoV-2; monoclonal antibody; prophylactic protection; variants of concern.