European regulators have approved the region’s first vaccine for respiratory syncytial virus (RSV), which causes thousands of hospitalisations and deaths annually.

The shot, called Arexvy, is made by British drugmaker GSK (GSK.L) and is designed to protect people aged 60 and over.

RSV typically causes cold-like symptoms, but is a leading cause of pneumonia in toddlers and the elderly.

The complex molecular structure of the virus and safety concerns with previous vaccine attempts had stymied efforts to successfully develop a shot since the virus was first discovered in 1956.

The approval on Wednesday by the European Commission, which follows a recent endorsement from the European Medicines Agency, comes about a month after the U.S. health regulator the gave Arexvy the green light.

The availability of the vaccine in Europe will depend on national recommendations and reimbursement discussions, but the first launches are expected this autumn ahead of the 2023/2024 RSV season, GSK said on Wednesday.

The company does not expect a significant rollout in Europe this year, GSK’s chief commercial officer Luke Miels told Reuters last month.

GSK, one of the world’s biggest vaccine makers, is relying in part on Arexvy to drive long-term growth, with the pending loss of patent protection for a key HIV compound and setbacks in its marketed oncology portfolio.

The U.S. Food and Drug Administration also approved a similar shot, Abrysvo, from rival Pfizer (PFE.N) last week.

Given the different definitions of the trial endpoints across the GSK and Pfizer trials, a direct comparison of efficacy is difficult.

The two companies are competing for a slice of an estimated $13 billion global market for RSV vaccines, according to modelling from Jefferies analyst Peter Welford, who in a note last month predicted Arexvy would ultimately rake in $4 billion in peak global sales.

While Pfizer will be a formidable competitor, GSK thinks it will ultimately capture more that half of the adult RSV market, TD Cowen analyst Steve Scala wrote in a note last month.

In Europe, RSV leads to over 270,000 hospitalizations and about 20,000 in-hospital deaths in adults over 60 each year.