Albert Bourla

Pfizer CEO Albert Bourla has tested positive for the coronavirus, he announced Monday.

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

Pfizer's mRNA coronavirus vaccine, which began to be widely used at the end of the first year of the global pandemic, has been one of the most widely used vaccines against the disease alongside the Moderna vaccine.

Israel has primarily used the Pfizer vaccine for its citizens, and was the first country to fully vaccinate a majority of its population as well as authorize booster shots of the vaccine.

The Pfizer vaccine has shown a decreased effectiveness in preventing infection over time and with the rise of new, more contagious variants such as the Omicron variant. However, studies have shown that the vaccine remains effective at preventing serious illness, hospitalization, and death from the coronavirus.