February 25, 2021 As Pfizer-BioNTech began shipping out its Covid-19 vaccinations in the US in December, pharmacists administering the jabs noticed something peculiar: Each vial of vaccine, labeled to hold five doses, contained a little extra fluid—enough, in fact, for a sixth dose. After getting clearance from the US Food and Drug Administration, the companies decided that this extra dose would count toward their dose commitments, meaning they could manufacture and ship fewer vials. There’s just one problem: Getting that sixth dose out of the vials often requires syringes that are in short supply. Without more of them, the global vaccination rollout could be stalled even further.