July 9 (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.