Promising Results from Allergy Spray Trial
A recent study published on Tuesday in JAMA Internal Medicine suggests that a safe, over-the-counter allergy nasal spray may effectively prevent COVID-19 infections. In a mid-stage trial, researchers observed a notable reduction in infections, with the spray appearing to cut cases by 67%. However, further research in larger trials is necessary to validate these preliminary findings.
Study Overview
The randomized, double-blind, placebo-controlled Phase 2 trial was conducted by scientists at Saarland University in Germany from March 2023 to July 2024. The study involved 450 healthy adults, approximately half of whom (227) used the generic antihistamine nasal spray, azelastine, three times daily. This spray is readily available over the counter in the United States. The control group received a placebo spray with the same formulation, minus the antihistamine ingredient. Both groups displayed similar rates of prior COVID-19 vaccinations and infections.
Key Findings
- After about 56 days of use, only five participants using the allergy spray (2.2%) contracted a SARS-CoV-2 infection, compared to 15 participants (6.7%) in the placebo group.
- This translates to a 4.5 percentage-point difference, representing a 67% reduction in COVID-19 cases, although the sample size is relatively small.
- Participants using the allergy spray took longer to contract COVID-19, averaging 31 days, versus 19.5 days in the placebo group.
- Furthermore, when those using the allergy spray did test positive, they had a shorter duration of detectable infection on rapid antigen tests, averaging 3.4 days compared to 5.1 days for those in the placebo group.
Additional Observations
Notably, participants using the allergy spray experienced fewer overall respiratory infections than those in the placebo group, with 21 infections compared to 49. This difference was particularly significant for rhinovirus infections, commonly associated with the common cold. These results align with prior studies indicating that azelastine may help combat various viruses that attempt to invade the nasal passages.
The findings suggest the potential for the allergy spray to provide a protective effect against COVID-19 through a broad antiviral mechanism that might also defend against other respiratory viruses. However, the specific workings of this mechanism within the nasal mucous membranes remain uncertain.
