He resigned as chairman of U.S. vaccine developer Vaxcyte Inc following a company request and quit Centessa Pharmaceuticals, which named him chief scientific officer at the newly-formed company last month.
Slaoui did not respond to a request for comment on LinkedIn on his resignations from the two companies.
He had on Wednesday night acknowledged his dismissal from Galvani Bioelectronics, a GSK-controlled firm, and issued an apology to the employee.
"I am deeply sorry for any distress caused. I would also like to apologize to my wife and family for the pain this is causing," Slaoui said in a statement.
He was appointed the head of the U.S. government's COVID-19 vaccine development program by former U.S. President Donald Trump last year and has held top positions at several drugmakers, including GSK.
The British drugmaker said an investigation into his conduct, performed on its behalf by an independent law firm, had substantiated allegations of harassment and inappropriate contact.
The probe, which is ongoing, was the result of a letter received by GSK containing allegations of inappropriate conduct toward a company employee years ago.
Slaoui joined Vaxcyte's board in July 2017 and became chairman in May 2018. He is also a partner at investment firm Medicxi.
(Reporting by Manas Mishra in Bengaluru; Editing by Arun Koyyur)