Almost a quarter of fully vaccinated U.S. adults have received a Covid-19 booster, according to a Kaiser Family Foundation (KFF) poll—and some areas may not have enough supply to meeting increasing demand amid colder weather and the omicron variant.

5 key considerations for the expanded booster shot rollout

More Americans are getting Covid-19 boosters

For the poll, KFF surveyed 1,820 U.S. adults between Nov. 8 and Nov. 22 for the latest edition of its ongoing Covid-19 Vaccine Monitor.

The omicron variant: The 'good,' 'bad,' and 'ugly' scenarios

According to the poll, 23% of fully vaccinated U.S. adults have now received a booster shot—more than double the 10% in October. The poll also found that around 40% of other vaccinated adults said they "definitely" will get a booster shot, while 19% said they "probably will get a booster shot as recommended.

In addition, the discovery of the omicron variant last week may also further increase booster uptake. On Monday, CDC Director Rochelle Walensky urged all American adults to get booster shots of Covid-19 vaccines, a change from the agency's previous recommendation that young, healthy adults "may" get a booster shot.

"The recent emergence of the omicron variant further emphasizes the importance of vaccination, boosters, and prevention efforts needed to protect against Covid-19," Walensky said.

Omicron may also increase demand for first vaccinations

In addition to increasing demand for booster doses, the omicron variant may also lead to more unvaccinated individuals getting their first dose of a Covid-19 vaccine.

According to a Morning Consult survey of 2,200 U.S. adults conducted between Nov. 29 and Nov. 30, almost 30% of unvaccinated respondents said the emergence of the omicron variant made them consider getting vaccinated against Covid-19.

In particular, around 11% of unvaccinated respondents said they "definitely" would consider getting vaccinated to protect themselves against omicron, while 19% said they "probably" would consider getting vaccinated.

Radio Advisory episode: The unanswered vaccine questions you should be tracking

Notably, unvaccinated respondents who are worried about the omicron variant said they would be more likely to get vaccinated, with 48% saying they would consider getting vaccinated.

Some pharmacies see temporary shortages amid rising booster demand

As demand for booster shots increases ahead of a potential winter surge and following the emergence of the omicron variant, some pharmacies are reporting vaccine shortages—leading them to cancel appointments and turn people away.

For example, Matt Willis, the public health officer for Marin County, Calif., said that all pharmacies in the area have been "impacted to some degree" by lack vaccine supply, and that some "have actually run out before the end of the day" and "have [had] to send people away."

"This is a logistical issue," Willis said. "The demand has increased so quickly that not all our pharmacies have been able to keep up with that demand."

According to ABC7 News, the lack of available supply may lead to delays of up to two weeks for people hoping to get their booster shots.

And in Oregon, residents seeking booster shots are seeing similar delays, particularly in large cities such as Portland, due to a lack of available vaccines and health care workers to administer them. Currently, the number of Oregonians seeking booster shots outnumber those seeking first doses by more than four to one, Oregon Live reports.

"We acknowledge that doses may be challenging to find right now," said Erica Heartquist, a spokesperson for the Oregon Health Authority (OHA). She added OHA is working to address shortages in some areas by redistributing doses to places with higher demand and that officials "request patience for Oregonians." (Japsen, Forbes, 12/2; Coleman, The Hill, 12/2; Jenkins, The Hill, 12/1; Galvin, Morning Consult, 11/30; Pena, ABC7 News, 12/1; Green, Oregon Live, 12/1)