Much was expected to protect babies from serious bronchiolitis. Massively tested this winter in several countries such as France, Sanofi’s Beyfortus, close to a vaccine, turns out to prevent a number of hospitalizations, two French studies confirming this observation.
“It is very encouraging to see that in real life all the studies are going in the same direction: significant effectiveness in preventing hospitalizations,” summarizes Isabelle Parent du Chatelet, responsible for infectious diseases at the Public Health France agency. This, in concert with the Pasteur Institute, made public two studies on Friday which provide a positive assessment of the effectiveness of the Beyfortus treatment.
Inject antibodies
These studies were eagerly awaited by doctors and public health authorities. Along with other similar treatments that have recently appeared, Beyfortus, developed by the pharmaceutical giant Sanofi, holds the promise of a major change in the fight against bronchiolitis. This affects many babies every winter, affected for days by respiratory problems. Generally not serious, they can however lead to hospitalization.
In the majority of cases, these symptoms are caused by a so-called respiratory syncytial virus (RSV). Nirsevimab, the Beyfortus molecule, is targeted against it. The goal is the same as a vaccine, but the principle is different. It is not a question of pushing the body to develop its own anti-RSV antibodies, but of directly injecting them.
It is part of a series of recent treatments, which for the first time carry the promise of immunizing many people against RSV: including Pfizer’s Abrysvo – in fact, a vaccine.
Reduce the risk of hospitalization
The health authorities of several countries therefore decided to launch vast baby immunization campaigns via Beyfortus in the fall, including France, which administered more than 200,000 doses and even had to ration them in the face of strong demand from parents.
This choice, widely supported by pediatricians, has however been the subject of some criticism, with some observers deeming it premature to make so much progress based solely on the clinical trials provided by Sanofi. It is therefore crucial to assess the real benefits of Beyfortus following this year’s bronchiolitis epidemic.
These benefits appear more and more indisputable in the countries where the treatment has been deployed. A study in Luxembourg, then another in Spain, showed in recent months that Beyfortus had significantly reduced the risk of babies being hospitalized.
Work carried out in France
The American health authorities also gave indications in this direction in March. These observations, which contrast with the few real-life studies already available on the Pfizer vaccine, are confirmed by the work carried out in France and published on Friday.
The two are complementary. The first, with a methodology similar to those carried out abroad, looked at a group of infants hospitalized in recent months in intensive care for bronchiolitis, and looked at whether they had received Beyfortus or not. It concludes that the treatment reduces the risk of going to intensive care by 75%, a figure which must however be put into perspective by the relatively small size of the sample of around 300 babies.
The second study completes these conclusions in another way: it is a modeling which takes into account numerous factors, such as the profile of previous years of the epidemic, to estimate the number of hospitalizations avoided by Beyfortus. According to researchers, thousands of babies have thus escaped the hospital: between 3,700 and 7,800 in total.
Preserve hospitals
What can we conclude from these two studies? It is not so much on an individual level that such treatment is essential. Unlike an illness like measles, the risk of complications from bronchiolitis is low for a healthy baby.
But “it’s really interesting to avoid overcrowding in hospitals, where pediatric services are saturated at this time,” says Simon Cauchemez who coordinated these models for the Pasteur Institute. Hence “the interest in a broad strategy that makes it possible to immunize infants who are otherwise well,” he concludes.