But after that, enforcement gets harder. Experts have said the next round of doses should be focused on people who are most at risk to catch or spread the virus, or for serious illness. That would include many service workers and people with underlying health conditions.

But there aren’t great enforcement tools to make sure that’s how things work.

“Eventually you’ll get to the point where there’s a lot of providers and distribution points involved in this plan, and it’s going to be harder and harder to ensure you adhere strictly to these priority groups. I’m sure there will be a point where we see line jumping,” said Josh Michaud, associate director of global health policy at the Kaiser Family Foundation.

“As far as enforcement, states will try to direct vaccines as best as they can to reach the populations they want to, but once they’re at those distribution points, it’s hard to control this process,” he added.