A universal vaccine capable of protecting against the flu, Covid and allergies?

It would protect us from the flu, the common cold, Covid-19, and all respiratory illnesses. A new vaccine, administered as a spray, appears to show promising evidence in the journal ScienceAdministered to mice so far, the vaccine has shown protection of at least three months against multiple viruses, bacteria, and even respiratory allergens. If these results were to be applied to humans, it would be the first universal vaccine available to protect against epidemics each winter.

Until now, vaccines have been formulated so that the body learns to defend itself against only one infection. This principle was developed by the Englishman Edward Jenner in the 19th century. Considered the father of immunology, he developed the first vaccine in history, the one against... smallpoxThe principle is simple: by administering a harmless part of the virus or bacterium, the immune system stimulates the production of antibodies and creates " memory cells against the disease. In the event of actual exposure, the body can then trigger a rapid and effective reaction.

Nasal spray, stronger than an intramuscular vaccine

This time, the Stanford team completely reversed its reasoning. The scientists are not betting on training the immune system against all winter illnesses at once. Instead, they are focusing their efforts on how immune cells communicate with each other. The acquired immune system is much older from an evolutionary perspective. explains to Science and Future Professor Bali Pulendran, an immunologist at Stanford University and co-author of this work. "It is composed of macrophages, dendritic cells, and neutrophils." (all white blood cells, editor's note)All of them provide rapid and broad protection against various microbes. However, this immune response is generally very short-lived: it fades after a few days, or at most three weeks.. »

To circumvent the problem, the team sought to activate the immune system directly in the lungs. However, the best route to reach this organ remains through… the nose. Hence the idea of a nasal spray. It is crucial to use the intranasal route. This allows us to directly target the airway immune system, resulting in strong, localized immunity—a result that could not be achieved with a more conventional intramuscular injection.“,” continues Professor Pulendran. “Because the innate immune system is like…” program "by each of our tissues – and not by a global pathogen. Thus, once it reaches the lungs, the vaccine succeeds in maintaining a localized immune state: the white blood cells, the macrophages, are in a state of permanent alert. By stimulating the macrophages, neutrophils, and dendritic cells mentioned earlier, it generates an adaptive response in the lung, which is effective against many different respiratory viruses and bacteria."

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Effective even against dust mites

Specifically, this nasal spray is composed of three main components. Two molecules stimulate macrophages and other immune cells in the lungs. In addition, a third component activates T lymphocytes of the adaptive immune system. These T lymphocytes are responsible for keeping the innate immune system active for longer than normal. After four doses of the nasal spray, mice showed immunity against coronaviruses, including Covid-19, and against bacteria that cause respiratory infections. They also lost their hypersensitivity to dust mites.

But beyond this remarkable achievement, how can the vaccine also reduce allergic reactions? Respiratory infections and allergies involve immune responses in the same lung tissues."The researcher recalls. This is how the nasal spray also made it possible to suppress a state of pathological allergic inflammation, while protecting against respiratory diseases.

Before celebrating too soon, we still need to find the same reaction in humans. In mice, this protection could last up to several months, a significant fraction of the animal's lifeThis result suggests that immunity in humans may last even longer. and that regular boosters would not be necessary"A question to which there is no answer until the results of a full-scale clinical trial are available."