Walgreens Boots Alliance Inc and CVS Health Corp are leading a program, in partnership with the federal government, that aims to vaccinate some 7 million people in more than 70,000 long term care facilities.

The companies had already began dosing some residents with Pfizer’s vaccine last week but their full rollout begins Monday.

Walgreens said it will provide vaccinations this week in about 800 facilities in 12 states. CVS did not specify how many facilities they would visit, but said they also plan to begin administering doses in a dozen states.

Some states have opted to wait for access to the Moderna shot, which is easier to transport and store, before vaccinating nursing home residents, the companies said.