Eloise LaCour clutches her dolly as a nurse takes her blood pressure, then swabs the 3-year-old's delicate arm with alcohol.
"Tickle tickle," says Eloise's mom, Angelica LaCour. She's trying to get a smile. "Mommy's going to hug you, OK?"
A Stanford University nurse carefully gives the little girl her shot. Eloise is one of 144 children in the country who are part of a Phase 1 clinical trial to test Pfizer-BioNTech COVID-19 vaccines in the most adorable of study cohorts — those 5 and younger.