Towards a vaccine against bronchiolitis

La bronchiolite est due au très contagieux « virus respiratoire syncytial » (VRS), qui crée chaque année une épidémie hivernale. Chez les plus de 65 ans, sa mortalité est en ligne avec celle de la grippe, et le VRS est la deuxième cause de mortalité infantile. Il touche 90 % des bébés avant leurs 24 mois.

Posted on September 7, 2022 at 7:15Updated on September 7, 2022 at 7:29 am

A vaccine against bronchiolitis, this common respiratory virus in infants and the elderly, is an old dream that is coming true. Vaccine candidates from several major pharmaceutical companies are released in the latest sprint. The first to touch the finish line could very well be the Frenchman, because at this stage, Sanofi’s injectable product is the most advanced.

According to our information, its evaluation by Europe could take place very quickly, possibly as early as September. If it gives a favorable opinion, marketing authorization for such a product would be a medical breakthrough, because the needs are massive.

90% of babies affected

Bronchiolitis is caused by the highly contagious “respiratory syncytial virus” (RSV), which creates an annual winter epidemic and pulmonary complications (pneumonia, etc.) in very young or frail people. Thus, among those over 65, their mortality is in line with that of the flu, the scientific journal ‘The Lancet’ recalled in August. RSV also affects 90% of babies within the first two years of life and is the second leading cause of infant death.

For premature babies, with an immature pulmonary system, there is a monoclonal antibody (Synagis, from AstraZeneca), but it is very expensive and requires five injections during the epidemic season with very limited effectiveness.

33 candidates

Only a more effective, simpler (for example, an injection that protects the entire viral season) and less expensive treatment would allow general vaccination. In the past, laboratories have tried to develop such a vaccine. But the research stopped in the 1960s when babies died in clinical trials.

For ten years, scientific advances have relaunched developments. Today, research abounds. “The Lancet” lists 33 candidate vaccines in various stages of clinical development around the world, including 9 in phase three trials. Called “vaccines” for simplicity, not all of them cause the body to produce antibodies that fight the virus (this is the definition of a vaccine). Some are injections of “monoclonal antibodies”, that is, antibodies directly, not made by the body itself. Which makes sense for babies, because their immune systems aren’t quite capable of doing that yet.

Test on 2,300 babies

To develop a vaccine, it remains to choose its target, between babies and the elderly. For Sanofi, it’s babies. In 2017, it joined forces with AstraZeneca, which is developing and manufacturing it in the United States. The French will market it, sharing the two costs and benefits equally, in case of success. Their product, Nirsevimab, is an ambitious monoclonal antibody: a single injection to protect through the viral season during the first year of life in healthy, premature or full-term babies.

Tested in 2,350 infants, Nirsevimab shows 79.5% efficacy against infections requiring medical treatment, compared to placebo. What to unclog hospitals in winter and reduce the consumption of antibiotics, if its cost makes a general vaccination possible. it is ambition.

In 2017, worldwide, for babies, “medical expenses directly related to RSV – including hospitalizations, outpatient consultations and follow-up care – were estimated at €4.82 billion,” Sanofi reminded investors in 2020. The request for marketing authorization for this potential blockbuster is scheduled for the second half of the year in the United States and has already been made in Europe. Hence the hope for an opinion issued in mid-September.

of the world behind

Sanofi, if successful, will not be alone for long. He pushes back on his heels. Another giant is also targeting the children’s niche with a monoclonal antibody: the American Merck MSD. But its phase three clinical trials only recently began. A possible commercialization in case of success will not be before 2023 at the latest.

What about the older people? Baby products may not work for them. A monoclonal antibody delivers the amount of antibody needed to neutralize the virus, depending on the weight of the patient. For an adult, such an amount would be needed that an injection would be impossible (an infusion would be needed!) and the cost unthinkable.

reserved for adults

But others point to this market of the elderly and immunocompromised, where analysts estimate potential sales of at least $10 billion a year. Once again, it’s coming soon. In June, Britain’s GSK successfully announced phase 3 trials of its vaccine candidate, followed by US rival Pfizer on August 25. The latter shows a protection of 66.7% of those over sixty years of age against an RSV infection manifested by two symptoms (86% by three symptoms).

Both present their dossier this semester to the regulatory authorities for its commercialization. And the next generation moves on. US biotech Moderna has a messenger RNA vaccine candidate in phase 3 testing and dreams of combining it with the one it is developing against influenza and its existing Covid vaccine, Spikevax, for a 3-in-1 respiratory vaccine. It hopes to achieve this within eighteen years . months.

#vaccine #bronchiolitis

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