(Reuters) - Pfizer ( PFE ) said on Tuesday its chief scientific officer Mikael Dolsten, a key figure behind the development of the company's COVID-19 vaccine, would step down after a more than 15-year career at the drugmaker.

The company said it would start identifying a successor for Dolsten, a process which is expected to last several months.

Dolsten joined Pfizer ( PFE ) as part of the Wyeth acquisition in 2009, when he was named president of Worldwide Research and Development with the responsibility to lead all of Pfizer's ( PFE ) research as well as development of all its treatments through mid-stage studies.