What you need to know about the Pfizer, Moderna and AstraZeneca vaccines

Three leading coronavirus vaccine candidates have dazzled the world with strong evidence they can prevent illness. The vaccines are made by different companies: One was developed by the giant pharmaceutical Pfizer and its German partner BioNTech; another by the biotechnology firm Moderna, in partnership with the National Institute of Allergy and Infectious Diseases, and the third is from the University of Oxford and its partner AstraZeneca. The first two have sought regulatory clearance in the U.S. to offer their vaccines to millions of people.