(Bloomberg) -- Pfizer Inc. gained US clearance for its RSV vaccine in older adults, the second drugmaker to bring a shot to a market estimated to be worth $10 billion within a decade. 

The US Food and Drug Administration approved New York-based Pfizer’s vaccine against respiratory syncytial virus, according to a statement Wednesday. Rival GSK Plc won authorization for a similar immunization less than a month ago. 

Pfizer’s RSV vaccine, called Abrysvo, will now go head-to-head with GSK to convince doctors and insurers to choose their shots. The RSV space is set to become even more crowded as Moderna Inc. is working on an injection for the respiratory disease that’s based on the same messenger RNA technology powering its Covid-19 vaccine. AstraZeneca Plc and Sanofi are also preparing a long-acting antibody — a preventive drug that will function somewhat like a vaccine — against RSV. 

While GSK beat Pfizer to FDA approval, the US company was first to win backing from the regulator’s advisory committee in early March. At the time, the advisers voted 7-to-4 that Pfizer’s RSV vaccine is safe and effective, with several raising concerns about a lack of data as well as two incidents of a rare nerve condition called Guillain-Barré syndrome among those who were vaccinated.

Pfizer is also seeking approval for an RSV vaccine for use in pregnant mothers to protect their newborns and was first to gain a nod from an FDA advisory committee for such a shot earlier this month. The shares rose 0.5% in trading before US markets opened.

Read More: Pfizer’s Maternal RSV Vaccine First to Win FDA Panel Support

Discovered in 1956, RSV quickly became recognized as one of the most common causes of childhood illness and can also prove dangerous for the elderly. The virus affects an estimated 64 million people globally and causes 160,000 deaths each year, according to the US National Institute of Allergy and Infectious Diseases.  

“This past RSV season demonstrated the serious consequences and potential health risks this virus poses for older adults,” said Edward Walsh, a University of Rochester Medical Center professor who conducted studies of the shot, in the Pfizer statement. The approval “recognizes significant scientific progress, and importantly helps provide older adults potential protection against RSV.”

It’s taken 60 years for scientists to develop protection against the common, sometimes deadly virus, in part because some efforts to develop vaccines in the 1960s turned out to exacerbate the disease. 


--With assistance from Fiona Rutherford.

(Updates with researcher’s comment in penultimate paragraph.)

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