Rhode Island is among a growing number of states which say they have been told to expect far fewer doses of the Pfizer-BioNTech COVID-19 vaccine in its second week of distribution, prompting concerns about potential delays in shots for front-line health care workers and others a high risk for contracting the virus.

Governor Gina Raimondo said in a statement late Thursday that Rhode Island health officials have learned that the state is expected to receive 6,825 doses for the week beginning Dec. 21, down from 10,725 doses, a cut of about 36%.

“We have heard accounts of similar reductions in other states, and no clear explanation has been provided by Operation Warp Speed,’’ Raimondo said. “We are calling on the Trump administration to honor its commitments and provide the full allocation to Rhode Island.”

But federal health officials said in a statement Thursday that “reports that jurisdictions allocations being reduced are incorrect,” and that official allocation numbers for next week have not yet been provided. “Operation Warp Speed remains on track to allocate enough vaccine for about 20 million Americans to receive their first doses before the end of the month, pending Moderna receiving an EUA,’’ said a spokesperson for the federal Department of Health and Human Services told National Public Radio.

Raimondo said that Rhode Island will continue to distribute the vaccine “as quickly as possible” to frontline health care workers. Dr. Philip A. Chan, an epidemiologist and medical director at the state health department, is scheduled to provide a detailed vaccine update at Friday’s press briefing. 

Senior Trump administration officials downplayed the risk of delays, citing a confusion over semantics, while Pfizer said its production levels have not changed.

The first doses of the vaccine were administered to health care workers in Rhode Island on Monday and Tuesday, through the state’s two largest hospital systems, Lifespan and Care New England. The pace of vaccinations is expected to increase next week, assuming Moderna receives federal authorization for its vaccine.

Emergency medical services and home health workers could begin receiving the vaccine next week, health officials have said, and nursing home staff and residents are expected to be vaccinated beginning December 28.

Lifespan, which received about 3,000 doses of Pfizer’s vaccine, said Thursday that it may be able to vaccinate nearly 600 more people against the virus than anticipated after discovering the vials that were expected to contain five doses were yielding six or even seven doses, Christina O’Reilly, a  Lifespan spokeswoman, said in an email. The discovery of the extra vaccine has been reported by hospital officials around the country.

--with reports by the Associated Press