Leyden Labs Develops Revolutionary Nasal Spray Against Flu Viruses

The meteorological winter has begun, and with it, the flu season. Yet there is hope: the Leiden-based biotech company Leyden Labs is working on a promising innovation that could drastically curb the annual wave of infections. The product is a nasal spray that blocks flu viruses in the nose before they enter the body.

Although the spray is ultimately intended for everyone, development is initially focused on those who need protection the most. “People who would otherwise end up in the hospital or worse,” says Koenraad Wiedhaup, CEO and co-founder of Leyden Labs. Each year, around one million people worldwide die from the flu, and another five million are hospitalized. The development is currently in the clinical phase, testing how safe and effective the product is in humans. According to Wiedhaup, a single daily dose of the nasal spray could provide a broad layer of protection, even against new flu variants and potentially pandemic threats like avian flu.

Protection
The strength of the nasal spray lies in the broadly acting antibodies it contains. These can protect against multiple flu viruses, “so the product doesn’t need to be redeveloped every year,” says Wiedhaup. In addition, Leyden Labs is working on a similar program for coronaviruses. “Not just against the coronavirus as we knew it, but also against new variants that may emerge through mutation.”

“It’s a utopia to think you’ll never get the flu again”
Ingrid de Visser-Kamerling, Research Director at the Centre for Human Drug Research (CHDR) and COO of INFECTA, emphasizes that the nasal spray is not a full replacement for vaccines. “It’s a utopia to think you’ll never get the flu again. The nasal spray blocks the virus in the nose, preventing you from getting sick. But it is especially important—if a pandemic breaks out—that vaccines are developed to provide long-lasting protection. So we need both.”

Different Mechanisms
A key difference between the nasal spray and the flu vaccine lies in how they work and their effectiveness. A flu vaccine protects only after the virus enters the body and has an effectiveness of between 30 and 40 percent, depending on the year and the type of vaccine. “With a vaccine, you train the body as if it were encountering a real flu virus,” explains De Visser-Kamerling. The immune system develops antibodies and a cellular response. The vaccine itself is quickly cleared from the body, but your own protection can last for weeks, months, or even years.

The nasal spray works differently. “The product creates a barrier in the nose, preventing the virus from entering the body. The immune system is not really activated for this at all.”