Pfizer (NYSE:PFE) announced on Tuesday that its chief scientific officer, Mikael Dolsten, will be stepping down from his role.

Dolsten, who has been instrumental in developing Pfizer’s COVID-19 vaccine, will retire after more than 15 years with the company.

Having joined Pfizer through the acquisition of Wyeth in 2009, Dolsten was appointed president of Worldwide Research and Development. 

Pfizer says the search for Dolsten's successor is on, with the process expected to take several months.