With a number of promising COVID-19 vaccine candidates in clinical trials, hopes for a safe and effective vaccine are rising. This raises a new set of challenges. How and where do we ramp up manufacturing capacity (vaccines, glass vials, etc.)? How do we manage equitable distribution of it to billions of people? Perhaps most crucially, how do we foster public trust with diverse communities, many of them underserved and high-risk, and convince them that immunization is safe and effective? Finally, even once these steps have been taken, will "vaccine nationalism" undermine our best-laid plans?