Virus vaccine put to final test in thousands of volunteers

Jennifer Haller, right, the first person to receive a trial dose of a COVID-19 vaccine, poses for a photo with her son Hayden, 16, and their dog Meg, Sunday, July 19, 2020, in Seattle. As the world’s biggest COVID-19 vaccine study gets underway more than four months after Haller and 44 others became the first participants in a phase-one coronavirus vaccine study that has produced encouraging results, Haller is encouraging other people to sign up for future trials. (AP Photo/Ted S. Warren)

Nurse Kathe Olmstead, right, gives volunteer Melissa Harting, of Harpersville, N.Y. an injection as the world’s biggest study of a possible COVID-19 vaccine, developed by the National Institutes of Health and Moderna Inc., gets underway Monday, July 27, 2020, in Binghamton, N.Y. (AP Photo/Hans Pennink)

The world’s biggest COVID-19 vaccine study got underway Monday with the first of 30,000 planned volunteers helping test shots created by the U.S. government — one of several candidates in the final stretch of the global vaccine race.