Demand for vaccines has dropped off markedly nationwide, with some states leaving more than half their available doses unordered.

Aiming to make it easier to get shots, Biden on Tuesday called for states to make vaccines available on a walk-in basis and he will direct many pharmacies to do likewise.

“You do need to get vaccinated,” Biden said from the White House.

To that end, the Biden administration is shifting the government’s focus toward expanding smaller and mobile vaccination clinics to deliver doses to harder-to-reach communities.

Ahead of the Food and Drug Administration’s expected authorization of the Pfizer vaccine for kids aged 12-15, the White House is developing plans to speed vaccinations for that age group.

Biden urged states to administer at least one dose to adolescents by July Fourth and work to deliver doses to pediatricians’ offices and other trusted locations, with the aim of getting many of them fully vaccinated by the start of the next school year.

The administration says that when states decline to take all the vaccine they have been allocated, that surplus will shift to states still awaiting doses to meet demand.

This week, Iowa turned down nearly three quarters of the vaccine doses available to the state for next week from the federal government because demand for the shots remains weak.

Data from the Centers for Disease Control and Prevention shows Louisiana’s coronavirus vaccination rate is well behind most states.

White House press secretary Jen Psaki said at the time nearly all states were ordering at or near their population allocations, which is no longer the case.