According to this story, he is not "fully" vaccinated. He had the first, but not the second. Planning to re-schedule the visit. I don't know if that is fact or not, but that is what this article says.
https://m.jpost.com/breaking-news/pfizer-ceos-israel-visit-cancelled-because-he-is-unvaccinated-report-661100
Pfizer CEO's Israel visit cancelled because he is not fully vaccinated - The Jerusalem Post
Bourla said in December that he has not yet received the vaccine yet because he does not want to "cut in line."
https://m.jpost.com/breaking-news/pfizer-ceos-israel-visit-cancelled-because-he-is-unvaccinated-report-661100