Common allergy nasal spray reduces risk of COVID-19 infection by 66%

An everyday hay fever spray may do more than tame sneezes. In a rigorously run German trial, adults who used azelastine nasal spray three times a day were less likely to catch COVID-19 than those who used a look-alike placebo. Fewer users also tested positive for rhinovirus, a leading cause of common colds.

The study ran for about two months and enrolled people with negative tests at the start. Results suggest a practical, on-demand layer of protection for crowded events, travel, and other high-risk moments—while bigger trials confirm who benefits most.

COVID-19 still disrupts daily life. Vaccines and built-up immunity help, but infections and long-lasting symptoms continue. That keeps interest high in simple tools you can add to your routine. Azelastine blocks histamine H1 receptors and calms nasal inflammation.

Lab work has hinted at direct antiviral activity against several respiratory viruses, including SARS-CoV-2, RSV, and influenza A (H1N1). Scientists have proposed multiple mechanisms, from interactions with ACE2 and the σ-1 receptor to blocking the SARS-CoV-2 main protease. Azelastine may also blunt ICAM-1, the cell “docking site” many rhinoviruses use.

Small treatment studies during the pandemic found lower viral loads in infected patients who used azelastine. Modeling then suggested a preventive payoff might be possible. The new trial asked the real-world question: if you use the spray daily, do you get sick less often?

Researchers at Saarland University Medical Center led a phase 2, randomized, double-blind, placebo-controlled study called CONTAIN. Regulators and ethics boards approved the protocol. Reporting followed CONSORT, and the statistical plan was written before enrollment.

From March 9, 2023, the team screened 587 adults and randomized 450 participants, ages 18 to 65, into two equal groups: 227 received azelastine 0.1% and 223 received a placebo. Everyone started with a negative rapid antigen test, had no acute illness, and avoided other nasal drugs and antihistamines.

Nearly all had received at least one COVID vaccine dose, with a median of three. The median time since the latest shot was 672 days, so most immunity came from past vaccination and infections rather than recent boosters.

The plan was simple. Participants sprayed one puff per nostril three times daily for an average of 56 days. After a known exposure or at the first sign of symptoms, they “escalated” for three days to five times daily. Twice-weekly staff testing with rapid antigen kits caught most SARS-CoV-2 infections, which were confirmed by PCR.

Symptomatic, antigen-negative people had PCR testing for SARS-CoV-2 and a multiplex panel covering dozens of other pathogens, including seasonal coronaviruses, influenza A and B, RSV, parainfluenza, adenovirus, HMPV, and rhinovirus.

By day 56, the main result was clear. In the intention-to-treat analysis, 5 of 227 people in the azelastine group (2.2%) had PCR-confirmed COVID-19. In the placebo group, 15 of 223 (6.7%) tested positive. That yields a risk difference of –4.5 percentage points and an odds ratio of 0.31, meaning roughly one-third the odds of infection compared with placebo. A per-protocol look pointed the same way: 2.8% versus 7.5%.

Several secondary results reinforced the headline finding. Symptomatic COVID-19 was lower with the spray: 1.8% compared with 6.3%. A time-to-event analysis also favored azelastine, with a hazard ratio of 0.31.

Among those who did become infected, time to infection stretched longer in the azelastine arm—about 31 days on average versus 19 days with placebo. The period of rapid-test positivity was shorter too, about 3.4 days versus 5.1 days. Fewer days testing positive could mean fewer days of higher contagiousness.

Rhinovirus stood out. Only 4 azelastine users (1.8%) had PCR-confirmed rhinovirus infections, compared with 14 people (6.3%) on placebo. That matters because rhinoviruses drive many colds and can worsen asthma and other lung conditions.

Across all lab-confirmed infections, there were 21 events in the azelastine arm (9.3%) and 49 in the placebo arm (22.0%). Unique participants with any confirmed infection followed the same pattern: 8.4% versus 18.8%.

Not every virus appeared during the study window, and several categories had fewer than 10 cases, so the broad antiviral signal should be interpreted with care.

Adverse events were common but mostly mild and familiar. The azelastine arm reported more treatment-related effects, led by bitter taste (9.3%), nosebleeds (6.6%), and fatigue (3.1%). A few participants in each arm stopped using the spray due to side effects, but investigators did not judge those withdrawals as treatment-related. Serious events were rare and unrelated to study products. No deaths occurred.

Earlier in the pandemic, monoclonal antibodies offered strong protection before variants reduced their value. The newest antibody option provides pre-exposure prophylaxis mainly for people with severe immune compromise and faces potency challenges as the virus evolves.

Vaccines remain essential for reducing severe disease. A simple, over-the-counter spray with activity across variants adds a flexible option you can control. As Professor Robert Bals put it, “During the observation period, 2.2% of the participants in the azelastine group became infected with SARS-CoV-2; in the placebo group, it was 6.7%—three times as many.”

This was a single-center study in mostly young, healthy, vaccinated adults. Larger, multi-site trials should test different dosing, longer follow-up, older age groups, and people with chronic conditions. Researchers also want to clarify effects on non-COVID pathogens and pin down which subgroups benefit most. The project involved teams from internal medicine, clinical pharmacy, and virology, with URSAPHARM Arzneimittel GmbH manufacturing the study sprays and supporting the trial.

Regular azelastine use could reduce COVID-19 and cold-virus infections during high-risk periods, such as winter waves, conferences, flights, or household exposures. Shorter rapid-test positivity may cut contagious days and help workplaces and schools rebound faster.

Because the spray is over the counter and familiar to allergy sufferers, it can scale without major new infrastructure. If larger trials confirm these results, clinicians may recommend azelastine as an add-on to vaccines, masks in crowded spaces, and staying home when sick.

That layered approach could lower community spread, protect people at higher risk, and reduce healthcare strain during respiratory virus season.

Research findings are available online in the journal JAMA Internal Medicine.

Note: The article above provided above by The Brighter Side of News.

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