Phase 1 study shows that nasal spray delivery of anti-flu antibodies is safe and effective however duration of action is only three hours before antibodies degrade.

Medical Mythbusting Commentary for February 6, 2026

Source:
Breakthrough nasal spray found to protect against all forms of flu

Reference:
Phase 1 and preclinical studies reveal safety, pharmacokinetics, and efficacy of intranasal delivery of the influenza antibody CR9114