President Joe Biden’s administration told governors on Tuesday that it would speed up deliveries of coronavirus vaccines beginning next week to about 10 million doses a week, according to a person familiar with the matter.

The accelerated deliveries, representing about a 16 per cent increase in the pace of supply, would continue for three weeks, the person said.

The new administration is scrambling to increase vaccinations in order to meet Biden’s goal of 100 million shots in his first 100 days in office. But the effort is constrained by limits on the number of sites and medical professionals who can give shots, not just by the supply of doses.

Biden said Monday that he thinks the U.S. can reach 1.5 million vaccinations per day, and that any American who wants a shot may be able to get one by spring. His deputies have tamped down expectations following that remark, returning to previous projections that most U.S. adults won’t be vaccinated until later in the year.

“Everybody won’t be eligible this spring, as you all know, even as the CDC continues to provide updated guidance,” White House Press Secretary Jen Psaki said Tuesday.