The biggest unknown is how long we will be left in purgatory. Operation Warp Speed officials have laid out an aggressive timeline to get nearly all Americans vaccinated by June, but this presumes several pieces going perfectly. The vaccines from Pfizer, which was just recommended for FDA authorization, and Moderna, which is expected to follow next week, cannot hit manufacturing delays, and additional vaccine candidates, from AstraZeneca and Johnson & Johnson, must earn speedy authorization from the FDA early next year. Pfizer earlier revised down the number of doses it will deliver in 2020 and separately has said it cannot supply any additional doses to the U.S., beyond the 100 million already ordered, before June. The timeline for authorizing AstraZeneca’s vaccine is up in the air after a messy clinical trial. And Johnson & Johnson’s has not yet been proved to work.

Your experience of this purgatory may depend on where you live. While a CDC committee sets recommendations of how to prioritize initially scarce doses, each state ultimately decides how to allocate the vaccines it receives. A person who qualifies as an essential worker in Illinois might not in Indiana. One city could end up opening vaccinations to the general public before its neighbor. This system is meant to be local and flexible, but that will necessarily mean a patchwork of policies that could come off as unfair or inconsistent.

“It is such a complicated and large logistical challenge that a lot of things will go wrong. A lot of things will not go to plan,” says Eric Toner, a senior scholar at the Johns Hopkins Center for Health Security. “The important thing is not to get hung up on that.” Hard trade-offs are ahead, as many groups have some claim to priority but they by definition cannot all be prioritized. Toner says not to lose sight of the ultimate goal: “Let’s just keep vaccinating people.”