CEO Albert Bourla said people will "likely" need a booster dose of a Covid-19 vaccine within 12 months of getting fully vaccinated. His comments were made public Thursday but were taped April 1. He also said it's possible people will need to get vaccinated against the virus annually. "It is extremely important to suppress the pool of people that can be susceptible to the virus," he told CNBC's Bertha Coombs during an event with CVS Health.