Third US vaccine could raise question: Which shots are best?

FILE - This September 2020, file photo provided by Johnson & Johnson shows a pharmacist preparing to give an experimental COVID-19 vaccine. The nation is poised to get a third vaccine against COVID-19, but health officials are concerned that at first glance the Johnson & Johnson shot may not be seen as equal to other options from Pfizer and Moderna. (Johnson & Johnson via AP, File)

WASHINGTON — The nation is poised to get a third vaccine against COVID-19, but because at first glance the Johnson & Johnson shot may not be seen as equal to other options, health officials are girding for the question: Which one is best?