Recent findings published in JAMA Internal Medicine indicate that a daily regimen of a safe, over-the-counter allergy nasal spray could potentially prevent COVID-19 infections. According to a mid-stage clinical trial, the nasal spray demonstrated an impressive 67% reduction in infections, though further studies are needed to confirm these results.
The trial, a randomized, double-blind, placebo-controlled Phase 2 study, was conducted by researchers at Saarland University in Germany from March 2023 to July 2024. The trial included 450 healthy adults, with approximately half (227 participants) using the allergy nasal spray azelastine, which is available over the counter in the United States. The control group received a placebo spray, identical in composition but lacking the antihistamine.
After approximately 56 days of usage, only five participants using the allergy spray (2.2%) tested positive for the SARS-CoV-2 virus, compared to 15 individuals (6.7%) in the placebo group. This significant 4.5 percentage-point difference translates to a 67% reduction in COVID-19 cases. Notably, the five individuals using the allergy spray who contracted the virus experienced a longer duration before testing positive—31 days compared to 19.5 days in the placebo group. Furthermore, those using the allergy spray had a shorter duration of positivity on rapid antigen tests, averaging 3.4 days versus 5.1 days for the placebo group.
Interestingly, participants who used the allergy spray also reported fewer overall respiratory infections, with 21 infections compared to 49 in the placebo group. This reduction was particularly notable for rhinovirus infections, the primary cause of the common cold. Previous studies have suggested that azelastine may offer protective effects against various viruses targeting the nasal passages.
The findings imply that the allergy nasal spray could provide a protective barrier against COVID-19 and other respiratory viruses through a general antiviral mechanism. However, the exact mechanism by which this occurs within the mucus membranes of the nose remains unclear at this time.
As with all clinical trials, there are limitations to consider. The small number of infections recorded in this study raises concerns about the robustness of the efficacy data, which may not hold in larger trials. The trial was also conducted in a single location and primarily involved healthy white women aged 20 to 46, limiting the generalizability of the results. Additionally, the study was funded by a pharmaceutical company associated with an azelastine nasal spray, although not the one available over the counter in the U.S.
Despite these limitations, the trial provides hope that this accessible nasal spray could serve as an effective viral prophylactic during respiratory seasons. This is particularly relevant given the current restrictions on access to COVID-19 vaccines in the U.S., which are primarily available to those aged 65 and older or individuals at higher risk. This limited access raises concerns, especially for healthy children and adults under 65, who are identified by medical experts as needing vaccinations.
With the ongoing challenges posed by COVID-19 and the seasonal influx of respiratory viruses, a simple nasal spray like azelastine could be a valuable addition to protective measures. The primary side effects are generally mild, including a bitter taste in the mouth, nosebleeds, and fatigue. As research continues, the allergy nasal spray may emerge as a supplementary tool in the fight against both COVID-19 and other respiratory illnesses.
