New York City on Wednesday canceled at least 23,000 vaccine appointments with supplies running low for first doses. Some states, like Colorado and Oregon, are scaling back eligibility for vaccinations or rejecting new, expansive federal guidelines in an effort to ration scarce shots…

The supply problem is one of the first major challenges Biden administration officials will face as they try to ramp up vaccinations to at least 1 million per day. President Joe Biden has pledged to hit 100 million vaccinations in his administration’s first 100 days, promising new federal resources for a vaccination effort that’s largely been left to the states. The new administration, which did not immediately respond to a request for comment, has said it will invoke the Defense Production Act to help ramp up vaccine manufacturing, while it’s also preparing to stand up mass vaccination sites.

State health officials say they desperately need better estimates weeks in advance on vaccine shipments from the federal government to plan everything from mass vaccination sites to smaller clinics. Instead, they’ve typically been informed less than a week before shipments.