(Reuters) -Pfizer Inc ( PFE ) said on Thursday that it sold 54.7% of its stake in German drugmaker BioNTech SE, more than five years after both firms formed an alliance that yielded a vaccine to combat the deadly COVID-19 pandemic.

This marks a strategic shift after Pfizer ( PFE ) and BioNTech began their partnership in 2018, collaborating on the development of mRNA-based influenza vaccines.

Their relationship intensified in early 2020 as the COVID pandemic unfolded, when the two companies joined forces to create the world's first authorized mRNA vaccine for the respiratory disease.

The partnership's mRNA vaccine, marketed as Comirnaty, generated annual sales of $37.8 billion at its peak in 2022.