Under court orders, the president will officially undo a key immigration promise, which will force asylum-seekers to wait months in Mexico ahead of their immigration court hearings in the U.S. — as long as Mexico accepts them.

One difference from the program under former President Trump’s administration: All migrant adults enrolled in “Remain in Mexico” will be offered the vaccine, although it can’t be required, according to two government immigration officials.

It’s unclear at what point in the process the migrants would be able to get their shots, whether before being turned back, when they return to the U.S. for their court hearing or at some other time.