Could a common nasal spray help block Covid-19? What a new study shows

By Katia Hetter, CNN

(CNN) — Amid the uncertainty surrounding eligibility for and access to the latest Covid-19 vaccine, a new study has found that a common nasal spray could help prevent infection.

This randomized placebo-controlled trial examined the effectiveness of the nasal spray azelastine in preventing Covid-19 infection, as published in the journal JAMA Internal Medicine on September 2. Researchers concluded that the chance of developing Covid-19 was about three times lower in the azelastine group compared with the placebo group.

What is azelastine, and do these study results mean we should start stocking up on this nasal spray? And, as coronavirus cases are once again rising, what precautions should people take to reduce their chances of infection?

To help with these questions, I spoke with CNN wellness expert Dr. Leana Wen, an emergency physician and clinical associate professor at George Washington University. Wen previously was Baltimore’s health commissioner.

CNN: What is azelastine nasal spray, and what is it currently approved for?

Dr. Leana Wen: Azelastine nasal spray, also referred to as the brand names Astelin and Astepro, is an antihistamine used to relieve symptoms of allergies, including stuffy or runny nose, itching, and sneezing. The medication is approved for both seasonal allergic rhinitis and perennial allergic rhinitis.

Seasonal allergic rhinitis is what most people think of as hay fever — allergy symptoms that flare up at certain times of the year, usually in the spring, summer or fall, when pollen from trees, grasses or weeds is in the air. Perennial allergic rhinitis, on the other hand, causes symptoms year-round. The condition is triggered by things that can be found throughout the year, such as dust mites, pet dander and mold.

First approved by the US Food and Drug Administration in 1996, this medication is now available in generic forms. A physician’s prescription is required, though one brand name called Astepro Allergy can now be purchased over the counter at pharmacies.

CNN: Why did researchers test this nasal spray to prevent respiratory illnesses?

Wen: Early in the pandemic, scientists looked at whether medications already on the market could be repurposed to fight Covid-19. Azelastine showed promise in some laboratory studies.

One study found that azelastine could bind to a receptor that the coronavirus uses to access human cells. Another report suggested that this antihistamine reduced virus levels in nasal tissue. And a third found that the medication may have a broader antiviral effect against other respiratory viruses, including the influenza virus.

Because this nasal spray is widely available, researchers wanted to test it on human participants in a rigorous setting to see whether azelastine could, in fact, reduce coronavirus infection. If so, this medication could be an inexpensive way to boost protection.

CNN: How was this new study performed, and what did it show?

Wen: This study was a randomized, double-blind, placebo-controlled phase 2 clinical trial involving 450 healthy adult volunteers in Germany, nearly all of whom (99.1%) had been vaccinated at least once with the Covid-19 vaccine. Participants were randomized to two groups. In one group, azelastine nasal spray was applied to each nostril three times a day for an average of 56 days. The other group received a placebo spray. Participants were tested for Covid-19 infection twice a week by rapid antigen test.

Researchers confirmed positive tests with laboratory polymerase chain reaction, or PCR, testing. Patients who tested positive for Covid-19 continued rapid antigen testing each day until the result was negative, so researchers could see how long the infection lasted. The study team also monitored participants for infection with other respiratory viruses, including the common cold coronaviruses, influenza, rhinovirus and parainfluenza.

Researchers found that the incidence of Covid-19 infection was significantly lower in the azelastine group compared with the placebo group. In the former, five of 227 participants (2.2%) tested positive, compared with 15 of 223 participants (6.7%) in the placebo group. The mean duration of having a positive test was also shorter in the azelastine group (3.40 days) compared with the placebo group (5.14 days).

What’s interesting is that the azelastine group was also less likely to contract other respiratory viruses. The total number of participants with a laboratory-confirmed infection of any of the viruses tested was 19 out of 227 (8.4%) in the azelastine group versus 42 out of 223 (18.8%) in the placebo group. Participants in the azelastine group also reported an average of only 1.73 illness days compared with 2.75 days for those in the placebo group.

CNN: How convincing are these results?

Wen: I think this was a well-designed study that points to a protective effect of azelastine nasal spray against SARS-CoV-2 and other respiratory viruses. The findings suggest that azelastine could be used as a preventive treatment against infection.

As the authors noted, the percentage reduction in Covid-19 infection is on par with what has been seen for other preventive measures, such as being up-to-date on Covid vaccines. These results are especially encouraging since azelastine nasal spray is inexpensive and widely available — not to mention that it already has decades of safety data. These findings are an important first step and set the stage for other clinical trials to see whether azelastine can reliably reduce the risk of respiratory virus infections.

CNN: Should people start using azelastine to prevent infections now?

Wen: Although the results are promising, keep in mind that the study was fairly small. The FDA has not approved azelastine to prevent Covid-19 or any other infection. I certainly would not encourage people to use the spray instead of other preventive measures, such as vaccination and masking.

CNN: Speaking of those other measures, what precautions should people consider as coronavirus cases are rising once again?

Wen: If you are able to get the updated Covid-19 vaccine, you should do so. If you are especially vulnerable to severe disease, try to avoid crowded indoor settings. If you must be in these settings though, consider wearing a well-fitting N95 mask or an equivalent. Finally, anyone experiencing respiratory symptoms should stay home to reduce the chance of spreading not only the coronavirus but also other respiratory viruses.

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