The data showed that the vaccine prevented mild and severe forms of Covid-19, the company said. And it was 94 percent effective in older adults, who are more vulnerable to developing severe Covid-19 and who do not respond strongly to some types of vaccines.
Pfizer, which developed the vaccine with its partner BioNTech, said the companies planned to apply to the Food and Drug Administration for emergency authorization “within days,” raising hopes that a working vaccine could soon become a reality.