A single vaccine protecting against multiple diseases typically seems out of reach. However, a recent study in mice shows that this could become a reality for respiratory diseases, thanks to a new method that mobilizes the lungs' natural defenses in an unprecedented way.
Unlike conventional vaccines that target a specific pathogen, this new formula works differently. It does not present the body with a fragment of a virus or bacterium, but instead seeks to stimulate and coordinate the natural defenses of the lungs in a lasting way. This method breaks with over two centuries of vaccine principles based on recognizing a specific enemy.
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Its mechanism relies on enhanced collaboration between the two main pillars of our immune system. The experimental vaccine first activates innate immunity, a rapid and general first line of defense. Unexpectedly, this activation is maintained for several months thanks to signals emitted by specialized immune cells, T lymphocytes, which are attracted to the site. This prolonged vigilance allows for an immediate and broad response against various intruders.
The results obtained in the laboratory are impressive in their scope. Mice vaccinated nasally resisted infections by SARS-CoV-2 and other coronaviruses. They were also protected against bacteria responsible for nosocomial pneumonia. Remarkably, the vaccine even attenuated allergic reactions to dust mites, demonstrating an ability to modulate very different types of immune responses. These protections lasted for at least three months after administration.
The next major step will be to evaluate the safety and efficacy of this approach in humans. Researchers plan to launch Phase I clinical trials. If these tests are conclusive, development could accelerate. The ultimate goal is to offer a nasal spray administered once or twice, capable of providing broad and simplified seasonal protection.
Such an advance would significantly change our way of protecting ourselves against respiratory diseases. It would offer a valuable tool for dealing with seasonal epidemics and emerging pandemic threats, while also potentially reducing the burden of common allergies.