SOUTH EUCLID, Ohio—The countdown started as soon as researchers removed the Covid-19 vaccine vials from the freezer at Senders Pediatrics. They had just two hours once the vials thawed to prepare the shots and give them to young children in the clinical trial.
A lot had to go right first. The containers holding the shot from Pfizer Inc. and BioNTech SE had to travel across town to a pharmacy without letting the vaccine become too warm. Pharmacists working in a sterile room, free of contamination, needed to assemble the shots in small doses safe enough for children. Finally, the vaccines had to be driven back to Senders for injection in the children as young as six months.