The COVID-19 pandemic has affected more than 700 million people worldwide. The highest risk is observed in immunocompromised individuals, including cancer patients. In this population, lower respiratory tract involvement is more common, along with increased need for hospitalization and oxygen support, as well as higher mortality.
Preventive strategies — vaccination and monoclonal antibodies — have significantly improved outcomes. However, some cancer patients remain at risk of breakthrough infections, as their immune response to vaccination is often reduced and insufficient for full protection.
Interferon-alpha (IFN-α) is a protein with antiviral, antimicrobial, antiproliferative, and immunomodulatory properties. Previous studies have shown that the interferon response plays a key role in protection against COVID-19. Intranasal IFN-α has already demonstrated efficacy in preventing common respiratory viruses such as rhinovirus and influenza. In particular, when used after exposure, IFN-α reduced the incidence of rhinovirus infection by 88% compared to placebo.
In the context of COVID-19, promising results have also been reported: intranasal IFN-α reduces SARS-CoV-2 shedding, while pegylated interferon-lambda lowers the risk of hospitalization.
Australian researchers conducted a study to evaluate the efficacy of an intranasal IFN-α spray for preventing COVID-19 and other respiratory viral infections in cancer patients.
Study Details
The study included 433 adult patients with solid and hematologic malignancies without prior COVID-19:
- 217 received intranasal IFN-α at a dose of 40,000 IU daily;
- 216 received a placebo.
90% of participants completed the study, and 389 individuals were included in the final analysis.
Efficacy and Safety of Intranasal IFN-α in COVID-19 Prevention
The overall COVID-19 incidence was 11.3%. It was lower in the IFN-α group than in the placebo group — 8.3% vs 14.4%, corresponding to a 40% reduction in infection risk.
The incidence of other respiratory viral infections was 5.1% and did not differ between groups. Among all detected infections, COVID-19 predominated, accounting for 69% of cases.
Final analysis of participants who completed the study confirmed these findings: COVID-19 incidence was 7.7% in the IFN-α group versus 16% in the placebo group — a 50% risk reduction.
The greatest reduction in COVID-19 risk with intranasal IFN-α was observed in patients under 65 years of age, in women, and in vaccinated individuals. No differences in efficacy were found depending on cancer type or ongoing anti-cancer treatment.
The frequency of adverse events did not differ between the IFN-α and placebo groups — 10.1% vs 6%. Serious adverse events were also comparable—4.1% vs. 2.8%. Epistaxis was rare and occurred at the same rate in both groups — 0.5%.
All-cause mortality did not differ between groups, at 0.5% in each group — both cases were unrelated to the intervention.
COVID-19 Severity and Clinical Outcomes
COVID-19 severity did not differ between the IFN-α and placebo groups: 90% of cases were managed in outpatient settings.
Hospitalization rates — both overall and infection-related — were also comparable between the IFN-α and placebo groups: 9.2% vs 10.2%.
SARS-CoV-2 seroconversion rates did not differ between groups: 5.7% vs 8.3%.
Conclusion
Intranasal interferon-alpha proved to be effective and safe for the prevention of COVID-19 in adult cancer patients. Daily use of intranasal IFN-α for 90 days reduced COVID-19 incidence by 40% in the full cohort and by 50% among those who completed the study.
The effect was most pronounced in patients under 65 years of age, in women, and in vaccinated individuals, with no differences based on cancer type or anti-cancer therapy.
IFN-α did not affect disease severity, hospitalization rates, mortality, or seroconversion. Most COVID-19 cases were mild. Intranasal IFN-α was well tolerated and did not increase the rate of adverse events.
Interferon-alpha may serve as an additional preventive measure alongside vaccination and monoclonal antibodies for COVID-19.
