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would nasal vaccines be more effective?

Almost a year after the start of the Covid-19 vaccination campaign, scientists are working on vaccines administered by the nasal route. They would attack the virus as soon as it enters the respiratory tract

What if we changed our method of vaccination against Covid-19? While more than 70% of the French population is doubly vaccinated, some still question the interest of serums which only imperfectly prevent contamination. As explained by our colleagues from “ West France This Wednesday, December 29, another method is seriously considered, the nasal vaccine.

“RNA vaccines are a little miracle, but there are limits. They do not generate local immunity. You can be vaccinated, but infected with the virus that will proliferate in the nasal mucosa. And we can pass it on, ”explained Éric Tartour, professor of immunology at the Georges-Pompidou hospital in Paris. To put it simply, the nose is the gateway for respiratory viruses. And you should know that our mucous membranes, located in the nose but in contact with the outside, have their own immune defense system: IgA antibodies and virus-killing cells.

On the same subject

A nasal vaccine against respiratory infections?

At this stage, whether it is immunization against influenza or against SARS-CoV-2, the vaccines are administered in injectable form with the aim of eliciting a systemic immune response. But since these infections are respiratory, Akiko Iwasaki’s team from Yale University in the United States is hypothesizing that a nasal vaccine could help protect the body. Indeed, “the best immune defense occurs when the virus enters the body,” she recalls.

A method already used

The idea is that if a vaccine provides enough IgG antibodies, it could induce local immunity in the mucous membranes. Basically, attacking the virus as soon as it enters the respiratory tract. Fighting diseases through the nasal passage is already being done. A nasal influenza spray is marketed in the United States, when some vaccines against H1N1 flu were administered nasally in 2009. Yale University has been moving in this direction for several months.

For Éric Tartour, this would be a major issue in the fight against the virus. “If we want to stop the epidemic, and it is a public health duty, mucosal vaccines will be needed. […] As long as vaccines do not prevent the transmission and therefore the spread of the virus, we will be under threat of new variants. »

Vaccines in development

Among the 300 vaccines still under development in the world, about twenty follow the mucosal strategy. Currently, three teams of French scientists are working on this new path. One of thePastor Institute de Lille has not yet published any results. Another from the joint laboratory between the Institut Pasteur and the start-up Theravectys has already been able to test its Lenti-S vaccine on animal models.

A last team of the University of Tours led by Isabelle Dimier-Poisson, researcher at the National Research Institute for Agriculture, Food and the Environment is working on “a protein vaccine without adjuvant, encapsulated in biodegradable nanoparticles based on corn starch”. the vaccine is administered nasally, but not in spray. “A syringe, equipped with a kind of filter”, would be responsible for administering the serum. He is part of the second generation of vaccines expected by the World Health Organization and is one of the tools that could lead to the end of barrier gestures and the wearing of masks.

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