DAILY prophylaxis with interferon-alpha (IFN-α) nasal spray significantly reduced the risk of COVID-19 infection in adult patients with cancer, according to findings from a randomized, double-blinded, placebo-controlled trial. The study provides new evidence that local immune activation in the nasal mucosa may offer targeted protection for immunocompromised populations at high risk of severe viral disease.
A total of 433 participants were enrolled and randomized to receive either IFN-α nasal spray (n = 217) or saline placebo (n = 216). Over the 90-day follow-up, the incidence of COVID-19 infection was 8.3% in the IFN-α group compared with 14.4% in the placebo arm, representing a 40% reduced risk (relative risk [RR]: 0.60; 95% credible interval [CrI]: 0.33–0.97). Rates of other community-acquired respiratory viral infections, including influenza, RSV, and seasonal coronaviruses, were identical between the two groups at 5.1%.
Analysis of the per-protocol cohort (n = 389) further supported these findings, with COVID-19 rates of 7.7% in the IFN-α group compared with 16.0% in placebo recipients (RR: 0.50; 95% CrI: 0.26–0.84). Subgroup analyses suggested the protective effect was most pronounced among patients younger than 65 years, women, and those who were previously vaccinated against COVID-19. No differences were observed across cancer subtypes.
Importantly, interferon prophylaxis did not impact secondary outcomes such as severity of infection, hospitalization, or mortality. The intervention was well tolerated with no new safety concerns, supporting its potential as a safe adjunctive preventive measure.
These results underscore the value of prophylactic strategies that target the initial site of viral entry in vulnerable populations. While vaccination remains a cornerstone of protection, IFN-α nasal spray may represent an additional tool for reducing infection risk in cancer patients, a group with heightened susceptibility to COVID-19 and related complications.
Reference:
Yong M et al. Interferon-α Nasal Spray Prophylaxis Reduces COVID-19 in Cancer Patients: A Randomized, Double-Blinded, Placebo-Controlled Trial. Clin Infect Dis. 2025;ciaf409.
