Pfizer CEO says a fourth booster shot 'is necessary' Pfizer CEO Albert Bourla said on Sunday that a fourth dose of the COVID-19 vaccine will be necessary to continue to help keep hospitalizations manageable and sicknesses more mild. "Right now, the way that we have seen, it is necessary, a fourth booster right now. The protection that you are getting from the third, it is good enough, actually quite good for hospitalizations and deaths," Bourla said while appearing on CBS's "Face the Nation."