► How does the current flu shot work?
This winter, more than 2000 deaths are due to influenza, according to data from Public Health France. If the flu still kills every year, there is a flu vaccine to protect the population. This is the best way to prevent the disease and reduce the risk of serious complications or death.
Nevertheless, its effectiveness does not reach 100%. This is due to the fact that its composition is determined each year by the WHO (World Health Organization) a few months before the outbreak of the epidemic peak and therefore it is only based on the likelihood that this or that influenza strain will be sequestered during the coming winter.
Why do we catch the flu in the winter?
" Influenza viruses are indeed changing rapidly and the composition of the vaccine must vary from year to yearexplains Combadière Behazine, Center for Immunology and Infectious Diseases (Inserm-Sorbonne University). However, since it takes 5 to 6 months to develop, the vaccine does not always target all circulating strains. "
► What does the injection mode change?
The Behazine Combadière team has been working for years on the influence of vaccine delivery routes on the quality of immune responses. Indeed, vaccines are usually administered in a "muscular way", usually in the delta muscle in the upper arm, have two effects: the first is to produce antibodies, these circulating proteins in the blood, secreted by white blood cells, and circling the virus to destroy it (called humoral response). The second is to stimulate the production of other white blood cells, called "killers," which directly destroy the infected cells (called the cytotoxic response).
Given the insufficient effectiveness of current vaccines, the team investigated the value of "cutaneous routes" by intradermal injection (into the dermis) or by transcutaneous administration (route of the hair follicle). For that clinical trial phase I (the product is safe?) And phase II (the product has a beneficial effect?) Was performed on 60 people aged 18 to 45, in collaboration with the Cochin-Pasteur Clinical Investigation Center for Vaccinology.
The published study shows that the skin routes in some test subjects induce a cytotoxic response after influenza vaccination (1). "This result argues for considering this route of vaccine injection, insofar as it causes an additional immune response to that obtained in the context of a conventional vaccination. These cytotoxic responses would be particularly protective in the elderly after influenza vaccination", explains Combadière Behazine.
► What else can this essay bring?
Apart from these results, the team has added new elements regarding the specific impressions left by these injection routes in the body. The researchers saw a dozen proteins of innate immunity appeared the day after the vaccine injection.
Towards a universal flu shot
The idea now is to identify among these ten biomarkers who can predict whether the immune response is good, and therefore whether the vaccine is effective. If the response is insufficient, the doctor may give a second injection or increase the dose. "However, these latest results still require further studies to validate the interest of these biomarkers and their subsequent use", concludes Behazine Combadiere.