Pfizer-BioNTech vaccine sharply reduces symptomatic Covid-19 in the real world, Israeli researchers say
Widespread vaccinations in the US won't come until the summer. Here's what's been driving down Covid-19 cases so far
Covid-19 cases have declined sharply. These factors will determine how pandemic unfolds from here, group of experts says
Nearly a third of US adults are undecided about the Covid-19 vaccine. They say friends and family could sway them
