Thread by @nytimes

On Monday, Pfizer and BioNTech announced preliminary results that suggested their coronavirus vaccine was more than 90 percent effective. Here’s what we know, and don’t know, about the vaccine. nyti.ms/2JRtxg2

In July, Pfizer and BioNTech initiated a late-stage clinical trial on a coronavirus vaccine. Half of the people got the vaccine, while the other half got a placebo of salt water. nyti.ms/2JRtxg2

Pfizer has said that it will likely apply for emergency authorization in the third week of November. Then, the FDA will consult with an outside advisory committee, and may take weeks to pore over detailed data about the vaccine’s safety and effectiveness. nyti.ms/2JRtxg2

Pfizer’s chief executive has said that it could have 30 to 40 million doses of the vaccine before the end of the year, enough for 15 to 20 million people to get an initial shot and a booster three weeks later. nyti.ms/2JRtxg2

Widespread success of coronavirus vaccines would be a huge boon to the world’s health, because Pfizer and BioNTech alone cannot meet the full demand. nyti.ms/2JRtxg2

It’s worth noting that the Pfizer news is still preliminary, and there is much that is still not known about how well the vaccine works. Here are more answers about what we know so far. nyti.ms/2JRtxg2