By Todd S. Purdum Dec. 22, 2020Reprints Molly Ferguson for STAT The advent of Covid-19 vaccines is a medical miracle, yet also a tantalizing and dangerous psychological milestone: It’s not the beginning of the end of the pandemic but, more likely, “the end of the beginning,” to borrow a phrase from Winston Churchill. The first day of distribution of vaccine in the United States illustrated the point. California accepted its initial delivery of 33,150 doses, just as it was beginning to average more than that number of new coronavirus cases every day. Such realities, though grim, have been easy to overlook. Exuberant headlines about vaccines — Now two! Millions more doses! — have grabbed attention, as have rightfully joyous social media photos of health care workers receiving their inoculations.