(Reuters) -British pharmaceutical giant GlaxoSmithKline and rival Pfizer ( PFE ) have agreed to end a lawsuit that alleged Pfizer's ( PFE ) respiratory syncytial virus (RSV) vaccine Abrysvo violated GSK's patent rights in its competing RSV shot Arexvy, according to a Thursday filing in Delaware federal court.

GSK and Pfizer ( PFE ) said in the filing that they would dismiss the case with prejudice, which means it cannot be refiled. Spokespeople for the companies did not immediately respond to requests for comment and more information, including whether the case was settled.

GSK, Pfizer ( PFE ) and Moderna ( MRNA ) have developed RSV shots approved by the U.S. Food and Drug Administration, with GSK's Arexvy responsible for the majority of U.S. RSV vaccine sales. The respiratory disease typically causes cold-like symptoms, but it is also a leading cause of pneumonia in toddlers and older adults.

GSK sued Pfizer ( PFE ) in 2023, arguing that the New York-based company's vaccine infringed GSK patents related to antigen technology. GSK said in the lawsuit that Pfizer ( PFE ) began working on its RSV program around 2013, at least seven years after GSK began developing its shot. 

Pfizer ( PFE ) denied the allegations and argued GSK's patents were invalid. It convinced a London court to invalidate related UK patents owned by GSK in a separate case last year.

GSK has also sued Pfizer ( PFE ) for patent infringement in the U.S. over technology in Pfizer's ( PFE ) blockbuster COVID-19 vaccine Comirnaty. That case is still ongoing.