MOSES LAKE — Only two-thirds of the expected shipment of coronavirus vaccine doses have arrived at Samaritan Healthcare since the rollout began in mid-December. A full shipment didn’t arrive last week, without explanation, according to hospital officials.

Even if the vaccine doses had arrived as quickly as was initially expected, most would still be sitting in cold storage. Of the nearly 2,000 doses of the Pfizer vaccine that arrived as planned, just over 500 have been administered to frontline health care workers and first responders, said Gretchen Youngren, executive director of development and communications for Samaritan.

The delays in administering the vaccine come in part because not all high-priority workers have come forward to be vaccinated, Youngren said.

At-risk health care workers and first responders have been prioritized by state and federal regulators until sufficient doses are available for the general public, but of the frontline workers who could be vaccinated by Samaritan, only about 50% have come forward for the first dose of vaccinations, Youngren said.

While providers in Washington state, unlike those in some states, such as New York, are able to exercise discretion when choosing whether to provide vaccinations to lower-priority recipients, Samaritan has not veered from state and federal guidelines, Youngren said.

Instead, Samaritan is turning to meet the needs of another high-priority population: residents and staff of long-term care facilities, such as nursing homes. That population was supposed to begin receiving vaccinations weeks ago through a federal partnership with private pharmacies, but the program appears to be facing serious delays, Youngren said.

“There’s been some frustration expressed at the state level with that,” Youngren said. “It just continues to get stalled.”

Samaritan sent out information Monday to long-term care facilities informing them if they unenroll from the federal program, they may instead begin to receive vaccinations from Samaritan, Youngren said.

In the meantime, Samaritan has ample space in the ultra-cold freezers needed to preserve Pfizer’s vaccine if there is a surplus, wrote Lloyd Stever, pharmacy director at Samaritan.

“We have ample storage to support current supply, and future shipments of the COVID vaccine,” Stever wrote. “Additionally, we are expecting the delivery of another freezer to further support storage and eventual distribution.”