Pfizer CEO Albert Bourla on Monday disclosed that he has tested positive for COVID-19 and will be going into isolation while he experiences “very mild symptoms.”


Bourla tweeted Monday morning that he had tested positive for COVID-19 despite having received four doses of his company’s COVID-19 vaccine.


The Food and Drug Administration (FDA) in March cleared the way for second coronavirus booster doses from Pfizer and Moderna to be administered to those over the age of 50 as well as immunocompromised individuals over the age of 12.


“I am thankful to have received four doses of the Pfizer-BioNTech vaccine, and I am feeling well while experiencing very mild symptoms. I am isolating and have started a course of Paxlovid,” he wrote.


Paxlovid is one of two COVID-19 antivirals that have been authorized for use by the FDA for the treatment of coronavirus, along with molnupiravir from Merck and Ridgeback.


Bourla, 60, added that he was confident that he would have a “speedy recovery” thanks to efforts that have been made over the past few years to combat the SARS-CoV-2 virus.


“I am incredibly grateful for the tireless efforts of my Pfizer colleagues who worked to make vaccines and treatments available for me and people around the world,” wrote Bourla.