Ultimately, Pfizer’s strategy may be about managing the public’s expectations, said Brandon Barford, a partner at Beacon Policy Advisors, a research firm. Pfizer could now explain any delay past October by “saying, ‘We’re being extra cautious.’ And you get kudos for it.”But if the opposite occurs, and Pfizer is seen to be pushing a vaccine before it is ready, the “potential fallout is enormous,” said Dr. Ranney, of Brown University. “We cannot afford to have a vaccine released for Covid-19 that is either unsafe or ineffective.”