Efficacy of Pfizer/BioNTech Covid vaccine slips to 84% after six months, data show
The efficacy of the Covid-19 vaccine developed by Pfizer and BioNTech fell from 96% to 84% over six months, according to data released Wednesday, a decline that could fuel Pfizer’s case that a third dose will eventually be required.
The data, released in a preprint that has not been reviewed by outside scientists, suggest the vaccine was 91% effective overall at preventing Covid-19 over the course of six months.
