Father RSV
'It's awful': Doctor explains RSV symptoms as cases surge
04:03 - Source: CNN
CNN  — 

A preventive treatment for lower respiratory tract infections caused by RSV got the go ahead from the European Commission on Friday, according to one of the companies that make it.

The treatment is the first of its kind to protect all infants in their first year of life.

A spokesperson from drugmaker Sanofi says that they’ve also submitted their research to the US Food and Drug Administration for approval. The company said it hopes the treatment will be available in the United States for the 2023 - 2024 RSV season.

This year, RSV, or respiratory syncytial virus, has overwhelmed pediatric hospitals all around the US. Nearly every child gets RSV prior to the age of 2, according to the US Centers for Disease Control and Prevention. While it can often be a milder respiratory infection for many children and most adults, studies show it is still a leading cause of hospitalization in all infants.

Globally, in 2019 alone, there were 33 million cases and more than 3.6 million hospitalizations. It’s estimated there were 26,300 in-hospital RSV deaths of children younger than age five and 101,400 deaths overall, according to a 2022 study published in the Lancet.

The new monoclonal antibody treatment is a joint project with AstraZeneca and Sanofi. It will be sold under the brand name Beyfortus (nirsevimab). Sanofi said it has been working in collaboration with AstraZeneca on the project for about five years.

The treatment is given to infants in a single dose shot at the time of birth or just before the start of the RSV season. And unlike with a vaccine where the body builds up its immunity in reaction to a vaccine over time, a monoclonal antibody works right away. The most common side effects are rash, injection site reactions and fever.

If approved in the US, Beyfortus would be the only single-dose RSV protective option for the general infant population. Sanofi said that broad protection is important, since 80% of infants that are hospitalized for RSV have no comorbidities.

Beyfortus can also be used for a second RSV season in children that remain highly vulnerable to RSV infection, typically meaning children with underlying medical conditions.

There is another monoclonal antibody treatment approved in the US and Europe called palivizumab, or Synagis, that protects against infection in high-risk infants. With that treatment, infants get an intramuscular injection every month during RSV season and it usually requires 5 doses. The treatment was approved in 1998.

Approval for Beyfortus from the European Commission was based on trial data that showed the treatment reduced the incidence of lower respiratory tract infections caused by RSV that needed medical attention by 70.1% compared to placebo in a Phase 2b trial, according to a news release from Sanofi. In a later stage Phase 3 trial conducted in 21 different countries, Beyfortus reduced the incidence of RSV-related bronchiolitis, inflammation of the tiny airways in the lungs, or pneumonia that needed medical attention by 74.5% compared to placebo.

“The totality of the data that we have generated across population indicates that protection is around 80% in the all-infant population,” said Jon Heinrichs, the global project head at Sanofi Vaccines Research & Development. “We believe it will make a huge difference on RSV.”

RSV has also placed a big burden on doctors office and hospitals even outside of a bad RSV season like the one the US is seeing right now.

“Imagine a situation where 80% of that disease could be prevented,” Heinrichs added.

For vulnerable infants and those whose mothers decline to be vaccinated, Dr. Helen Chu, an infectious disease specialist at the University of Washington, says Beyfortus could be a “game-changer.”

The other advantage with a treatment like this is that if an RSV season were to start early like it did this year, with RSV hospitalizations shooting up to levels typically seen in December, it can deliver protection just in time for any infant.

Get CNN Health's weekly newsletter

Sign up here to get The Results Are In with Dr. Sanjay Gupta every Tuesday from the CNN Health team.

Beyfortus would also protect the child directly. A vaccine given to a mother to offer passive protection to a child wouldn’t necessarily work for a child born after the RSV season is over. By then, the immunity would likely have worn off, Heinrichs said. Half of infants that are hospitalized with RSV are born outside of the RSV season.

“So it’s really critically important in our minds at least to protect all infants from RSV disease, and we think this is the only way to do it,” Heinrichs said.

In the US, there are four new RSV vaccines that may be nearing review by the FDA, and more than a dozen are going through trials right now. Most of those vaccines are for adults. A vaccine for children is further down the road, experts say.

CNN’s Brenda Goodman contributed to this report