what Sanofi’s “vaccine” could change

It is one of the most dreaded diseases of parents of young children. Each year, bronchiolitis affects 30% of babies under 2 years old in France, according to the Ministry of Health. Most often due to the respiratory syncytial virus (RSV), this respiratory infection of the small bronchi, very contagious, is benign most of the time. However, it remains one of the main causes of winter hospitalization in infants and, in very rare cases (0.08%), can lead to the death of the child.

So many elements which, for years, have led pharmaceutical companies to take an interest in bronchiolitis. This is the case of the French Sanofi and the British AstraZeneca, which are associated to develop a “vaccine”, nirsevimab, just approved by the EMA, the European Medicines Agency. Published in March 2022 in the New England Journal of MedicinePhase III trial results showed a 74.5% reduction in lower respiratory tract infections caused by SRV and required medical management.

A single dose

Regularly presented as a “vaccine”, Beyfortus, its trade name, is in fact a monoclonal antibody, to be injected in the first months of a child’s life, before or during the bronchiolitis epidemic, between the end of October and January. . It confers what is called passive immunity, unlike live attenuated vaccines (such as BCG or MMR), which contain an infectious agent and lead to active immunity.

A novelty ? Not entirely. “Other monoclonal antibodies exist against RSV, such as Synagis, but it requires effective injections and only concerns premature or at-risk children, i.e. barely 2% of children”, indicates the president of the French Society of Pediatrics, Professor Robert Cohen, who participated in the coordination of the clinical trial in France.

The Beyfortus only requires one injection and could protect for six months. “This does not mean that there is no longer any protection afterwards, but it does make it possible to overcome the fragility of children vis-à-vis this disease”, says Robert Cohen. For him, the arrival of such a treatment would therefore mark a major turning point in terms of child health, but also a change in the culture of public health. “For a very long time, we were only interested in vaccines that prevented mortality. This is why the rotavirus vaccination (responsible for gastroenteritis, Editor’s note) one took years to be authorized in France. Today, and more particularly since the Covid, measure how heavy a visit to the emergency room or hospitalization can be, not only for young patients and their families, but also for health services. »

Hospitals overwhelmed every year

By limiting the number of RSV infections, which also cause pneumonia, bronchitis and otitis, Beyfortus would lighten the heavy load on the hospital each winter. Last year, the epidemic, which occurred earlier than usual, had led to the transfer of several infants, for lack of space in the surrounding structures.

Now approved by the EMA, the Beyfortus still has to get the green light from the European Commission, which should decide within two months. It will then be up to the French authorities to develop national recommendations. For Robert Cohen, the treatment should therefore not be available for at least a year.


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