Daily squirts of a safe, over-the-counter allergy nasal spray may prevent COVID-19 infections from taking hold, according to results published Tuesday in JAMA Internal Medicine. In a mid-staged trial, the spray appeared to reduce infections by promising 67 percent, though a larger trial will need to confirm that robust efficacy.
The trial was a randomized, double-blind, placebo-controlled Phase 2 trial conducted by researchers at Germany's Saarland University between March 2023 and July 2024. The study included 450 healthy adults, about half of whom (227) spritzed their noses three times a day with the generic antihistamine nasal spray, azelastine, which can be purchased over the counter in the US. The placebo, meanwhile, was a spray with an identical composition except for the absence of the antihistamine. The two groups had similar mixes of previous COVID-19 vaccination and infection statuses.
After about 56 days of frequent mistings, only five people using the allergy spray (2.2 percent) caught a SARS-CoV-2 infection, while 15 people using a placebo (6.7 percent) got the pandemic infection. That 4.5 percentage-point drop represents a 67 percent reduction in COVID-19 cases, though the numbers here are small. Still, the researchers noted that the five people using the allergy spray who contracted COVID-19 took more time to get the infection than the 15 in the placebo group (31 days versus 19.5). This could hint that the spray held off some infections from exposures early in the trial. And when the allergy spray users did get COVID-19, they were positive on a rapid antigen test for less time than those infected in the placebo group (3.4 days versus 5.1 days), suggesting they cleared the virus a bit faster.
Intriguingly, people using the allergy spray also had fewer respiratory infections overall compared with those in the placebo group (21 infections versus 49 infections). This was particularly the case for rhinovirus infections, the cause of the common cold. These findings are backed by several earlier studies suggesting that azelastine can fight off various viruses that try to invade our noses. Overall, the findings suggest that the allergy spray may protect against COVID-19 using a general antiviral mechanism that can guard against other respiratory viruses. But what that mechanism might be on the mucus membrane of the nose is unclear for now.
COVID context
Like all trials, there are limitations. As mentioned, the number of infections here is small—the impressive efficacy numbers could potentially vanish in a larger trial with more infections. And, while the trial had a high-quality design, it was undertaken in just one location in Germany and mostly involved healthy white women between the ages of 20 and 46, so the findings are not generalizable. The study was also funded by a pharmaceutical company that makes an azelastine nasal spray (though not the one that is sold over the counter in the US).
Still, with the previous studies, the trial offers some hope that this accessible nasal spray could be used as a viral prophylactic for respiratory seasons in the future. And the results land at a time when access to COVID-19 vaccines—which have firmly proven to be safe and highly effective—has been severely restricted in the US by health secretary and anti-vaccine activist Robert F. Kennedy Jr.
As it stands now, it appears that only people ages 65 and over, and those at higher risk of COVID-19 will have access to the shots this year, though some aspects of that access are murky, including how people will prove they're at high risk. For healthy children, teens, and adults under 65, there may be no access or extremely limited access. That includes groups that medical experts recommend get vaccinated, namely healthy pregnant people and children ages 6 months to 23 months, both of which are considered at high risk from COVID-19 by medical experts, but not federal guidance under Kennedy. Experts also recommend access for healthy people who have contact with vulnerable people, such as cancer doctors, people who live with immunocompromised family members, and people who work in nursing homes.
With limited vaccine access and the normal slew of respiratory viruses on the horizon, a simple nasal spray is an appealing addition to the defenses. The main side effects are fairly minor, including bitter taste in the mouth, nosebleeds, and tiredness.
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