Though there’s still a lot scientists don’t know about omicron, it is unlikely to be the last variant that emerges from this pandemic. The question is whether omicron will now force the global vaccination campaign to recalibrate, especially if the definition of fully vaccinated begins to evolve from generally two doses, to three. To get a better sense of the broad challenges, Vox spoke to Wafaa El-Sadr, an expert on infectious diseases and global health at Columbia University.