Facade with logo at office of pharmaceutical company AstaZeneca, South San Francisco, California, April 11, 2020. (Photo by Smith Collection/Gado/Getty Images) LONDON (AP) - Scientists at Oxford University say their experimental coronavirus vaccine has been shown in an early trial to prompt a protective immune response in hundreds of people who got the shot.British researchers first began testing the vaccine in April in about 1,000 people, half of whom got the experimental vaccine.