Millions of Americans are in line to get one of now three vaccines approved by the FDA for emergency use. The latest — Johnson & Johnson's one-dose adenovirus vector — can be stored for up to three months in a fridge and is easier to transport. Johnson & Johnson is no stranger to the technology, having used it in its Ebola vaccine. Despite its rollout goals of 100 million doses by June, Rick Nettles, MD, vice president of medical affairs at J&J's Janssen division, says researchers are already looking ahead to expanding its use for children and pregnant women. He joins this week's episode.