Retrospective 625 high-risk university students in Thailand showing reduced SARS-CoV-2 infection rates with nitric oxide nasal spray prophylaxis. Among students exposed to infected individuals, those voluntarily using treatment (n=203) had a 6.4% infection rate compared to 25.6% in the control group (n=422) (p<0.0001). Adverse events were limited to mild nasal burning or irritation in 11.4% of users, with no severe events reported. Authors note the study is limited by its retrospective, open-label nature and lack of randomization. Students who chose the treatment may have been more health-conscious or compliant with other protective measures. Authors are executives of the manufacturer.

Targeted administration to the respiratory tract provides treatment directly to the typical source of initial SARS-CoV-2 infection and replication, and allows for rapid onset of action, higher local drug concentration, and reduced systemic side effects.