Vaccines from Pfizer, Moderna and others will have the power to one day end the pandemic, or at least tame it—but only after 70 percent or more of the world’s population gets inoculated against Covid-19. So far, the rollout has been anything but smooth. Big drugstores say they’re ready to come to the rescue. Robert Langreth and Angelica Lavito describe the potentially massive vaccine infrastructure that the neighborhood pharmacy could provide.