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Covid-19: when will a nasal vaccine be available to limit the transmission of the virus? -Coronavirus



How to stop the transmission of the virus between people and, thus, deal a fatal blow to the covid-19 epidemic? The first RNA vaccines, based on the Wuhan virus strain, only offer very reduced efficacy in this area. The fault, in particular, with the arrival of multiple variants which escape the immune response induced by these vaccines.

Will the solution come from vaccines administered by the nasal and oral routes, entry points for SARS-CoV-2 into our body? At the beginning of September, two candidates obtained authorization from their country. Approved by the Chinese authorities, the inhalable vaccine from CanSino Biologics can be administered to the Chinese by the nasal route, via a sprayer, as a booster dose, on a date which has not been specified. This vaccine shares the same technology as its injectable version in the arm (viral vector by adenovirus). But little chance of seeing it land in Europe, where no Chinese vaccine has yet been authorized by the European Medicines Agency, despite procedures underway for many months.

Covid-19: the latest news

“The right tactic of war”

A few days later, an Indian vaccine developed by Bharat Biotech received the green light from the country’s authorities to be administered as drops in the nose.

These two authorizations mark the realization of a hope born soon after the start of the pandemic. As early as July 2020, researchers from the Institut Pasteur and the TheraVectys laboratory had published a study showing that a vaccine candidate delivered nasally induced “strong antibody-type responses, very effectively neutralizing SARS-CoV-2, as well as ‘an abundant cellular response’.

This type of vaccine which acts on the mucous membranes could block the entry of the virus into our body, much better than those injected into the arm. The reason ? “The immunity that we have in the mucous membranes – in the mouth, in the digestive tract, etc. – is carried by a particular type of antibody, type A, which is less well produced when the vaccine is injected into the arm”, explains Sandrine Sarrazin, researcher at the Marseille-Luminy immunology center (CNRS / Inserm / Aix -Marseille University).

The puncture in the deltoid muscle will, in fact, mainly produce another family of antibodies, type G, which we will then rather find in the depths of the human body, in the lymph or nestled in the organs. They will, of course, offer good protection against serious forms of the disease, but will not migrate easily to the mucous membranes.

For Sandrine Sarrazin, nasal vaccines are therefore “the right tactic of war” because “their mode of administration is identical to the mode of contamination: we put the vaccine in contact with the mucous membrane at the very place where the virus enters. We then have good type A mucosal immunity, which really blocks the infection”.

A French vaccine not before the end of 2023

In France, a vaccine candidate using this technology is in the running. Based on the principle of recombinant protein, it was developed by Inrae (National Research Institute for Agriculture, Food and the Environment) and the University of Tours. A new start-up, LoValTech, has taken over to ensure its development. Very recently, it hoped that its clinical trials would begin by the end of the year, in order to achieve marketing authorization for the end of 2023-beginning of 2024. One of the advantages of this vaccine? It integrates the Spike protein of the virus (which allows it to enter our cells), but also other antigens which are not subject to mutations, which could maintain its effectiveness on several types of variants.

Other countries are working on nasal versions, and in particular on the basis of already existing vaccines such as that of the Swedish-British AstraZeneca and the Russian Sputnik-V.

Mucosal vaccines are already used for various diseases. This is the case with the flu. In France, the High Health Authority had given authorization to use it for the 2020-2021 season, in a context of possible supply tension. This is Fluenz Tetra (live attenuated virus technology), reserved for children aged 2 to 17 at risk of severe form.



letelegramme Fr Trans

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