Pfizer shares were 0.9% higher in premarket U.S. trading, with BioNTech gaining 1.3% in Frankfurt.
Pfizer Inc. and BioNTech SE said a booster shot of their Covid-19 vaccine restored full protection in a large study, results that are likely to bolster the argument for giving a third dose more widely.
A booster was 95.6% effective against symptomatic Covid in the study, which followed 10,000 people aged 16 and older, the companies said on Thursday.
