Pfizer CEO Albert Bourla announced Monday that he has tested positive for COVID-19 — and praised his company’s vaccines while announcing his diagnosis.

“I would like to let you know that I have tested positive for #COVID19. 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 said in a series of tweets.

“We have come so far in our efforts to battle this disease that I am confident I will have a speedy recovery,” Bourla said. “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.”