Pfizer, BioNTech initial vaccine results impress, but scientists remain cautious

FILE PHOTO: A woman holds a small bottle labeled with a "Coronavirus COVID-19 Vaccine" sticker and a medical syringe in front of displayed Pfizer logo in this illustration taken, October 30, 2020. REUTERS/Dado Ruvic/File Photo

CHICAGO/LONDON (Reuters) - Scientists on Monday said initial trial results for Pfizer Inc and BioNTech's <22UAy.F> coronavirus vaccine far outpaced their expectations for protection against a completely new disease, but that many questions remain unanswered.

The drugmakers said their vaccine was more than 90 percent effective at preventing COVID-19, based on data from the first 94 people in the trial to become infected with the coronavirus.