Kentucky Gov. Andy Beshear spoke out Monday after Walgreens stores in Louisville and Lexington, Kentucky, gave COVID-19 vaccines to members of the general public.

Beshear said at a press conference that last week, the pharmacies were left with extra doses of the vaccine after administering it to long-term care facilities, so, they offered the leftover doses to average citizens. This, the governor said, does not follow government protocol, as the vaccine is not yet being given to the general public.

"I don't think that this was intentional, and we have to understand that in an undertaking this massive that mistakes are going to happen," Beshear said. "I believe that here a mistake happened in the thawing, but the reaction wasn't what it should've been."

In a statement, Walgreens said that per the Centers for Disease Control and Prevention's guidance, Pfizer’s COVID-19 vaccine can be at refrigerated temperatures for only five days, so, to avoid wasting doses of the valuable vaccine after giving it to at-risk adults in long-term care facilities, they used the leftover doses they had on residents.

The doses were offered to local first responders, Walgreens pharmacy and store team members and residents of the community, many of whom were over age 65, Walgreens said.

"These measures were taken to ensure every dose of a limited vaccine supply was used to protect patients and communities," the company added. "We will utilize excess vaccine inventory in priority patient populations and continue to work closely with state and federal health agencies in our efforts to vaccinate residents in long-term care facilities and ensure requested doses meet their needs."

Los Angeles County officials announced Monday that it will require anyone who traveled or is planning to travel back into the county to quarantine for 10 days.

"The best way to safely quarantine is to not leave your home or allow any visitors to your home, and to find others who can help you buy groceries and other essential necessities," The Los Angeles County Department of Public Health said in a statement.

The county is close to 10,000 coronavirus related deaths and since Nov. 9, the average daily hospitalizations of people with COVID-19 increased more than 670%, according to the Health Department.

Los Angeles Country recorded 44 new coronavirus deaths Monday, bringing the total number of fatalities to 9,555, according to the county Health Department.

LA County Director of Public Health, Dr. Barbara Ferrer noted that the county is on its way to a stark milestone.

"[We] could be approaching a total number of 10,000 deaths shortly, which will be the saddest number since the start of the pandemic," she said at a news conference.

Roughly 13,661 new cases were reported Monday and the county hospitalization rate is now at 6,914, the highest since the pandemic began, according to Ferrer.

"Last week we lost someone due to COVID-19 every 10-15 minutes," she said.

In the meantime, the county has administered 66,628 doses of the coronavirus vaccine at acute care hospitals and 1,478 doses at skilled nursing facilities as of Dec. 26, according to the Health Department.

-ABC News' Cammeron Parrish contributed to this report.

Vice President-elect Kamala Harris and her husband Doug Emhoff will receive the COVID-19 vaccine Tuesday morning in Washington D.C, the Biden transition team confirmed to ABC News on Monday.

President-elect Joe Biden received the first dose of the two-dose vaccine on live television last week.

-ABC News' Beatrice Peterson contributed to this report.

Public Health England does not recommend mixing COVID-19 vaccines from different suppliers, according to the agency's head of immunizations, Dr. Mary Ramsay.

"We do not recommend mixing the COVID-19 vaccines -- if your first dose is the Pfizer vaccine you should not be given the AstraZeneca vaccine for your second dose and vice versa," Ramsay said in a statement Saturday. "There may be extremely rare occasions where the same vaccine is not available, or where it is not known what vaccine the patient received. Every effort should be made to give them the same vaccine, but where this is not possible it is better to give a second dose of another vaccine than not at all."

The clarification comes amid questions over the British government's updated guidance on COVID-19 vaccines, which now says that if individuals who received the first shot go to an immunization site where that same vaccine is not available for a second shot, or if the first vaccine received is unknown, "it is reasonable to offer one dose of the locally available product to complete the schedule."

"This option is preferred if the individual is likely to be at immediate high risk or is considered unlikely to attend again," the guidance adds.

The guidance, which was updated Thursday, also notes that "there is no evidence on the interchangeability of the COVID-19 vaccines although studies are underway," and thus "every effort should be made to determine which vaccine the individual received and to complete with the same vaccine."

Next week, the United Kingdom is set to begin distribution of a COVID-19 vaccine developed by England's University of Oxford and manufactured by British-Swedish pharmaceutical giant AstraZeneca, after the drug was approved Wednesday for emergency supply. Another COVID-19 vaccine developed by U.S. pharmaceutical giant Pfizer and its German partner BioNTech was approved in the U.K. on Dec. 2 and rollout began a week later.

ABC News' Zoe Magee contributed to this report.