SALEM, Ore. -- The Oregon Health Authority announced Thursday that its allocation of the Pfizer vaccine has been cut by nearly 15,000 doses for the week of Dec. 20.

More Pfizer-BioNTech vaccine deliveries are scheduled the weeks of Dec. 20 and Dec. 27, when allocations of 25,350 and 48,750, respectively, are expected to arrive in Oregon.

That allocation of 25,350 doses is a reduction from the original amount of 40,950 Oregon was previously scheduled to have allocated during that week.

Federal officials notified the state about the change Thursday with seemingly no explanation.

OHA officials said between 300,000 and 400,000 health care workers and long-term care facility staff and residents in Oregon are slated for vaccination against COVID-19 during the first phase of the state's vaccination distribution effort.

The remaining 19,500 doses from this week's batch will be distributed to health care facilities around the state over the next several days.