Pfizer Inc. /zigman2/quotes/202877789/composite PFE -1.76% CEO Albert Bourla tested positive for COVID-19. He tweeted Monday that he received four shots of the COVID-19 vaccine the company developed with BioNTech SE /zigman2/quotes/214419716/composite BNTX -1.22% , is "experiencing very mild symptoms" and has started taking Paxlovid, Pfizer's COVID-19 antiviral.





