'Expect the unexpected' as vaccinations beginTo view this video please enable JavaScript, and consider upgrading to a web browser that supports HTML5 video12/10/2020December 10, 2020US infectious disease expert William Schaffner tells The Day's Brent Goff that allergic reactions to the BioNTech-Pfizer vaccine in two UK patients underline that bumps in the road are inevitable as COVID vaccination programs are rolled out. https://p.dw.com/p/3mYAVAdvertisement