When Oregon health officials found themselves trapped on a road in a snowstorm, they walked car to car to administer leftover COVID-19 vaccine doses.

The staff and volunteers from Josephine County Public Health Department held a mass vaccination event at a high school Tuesday before getting trapped in the storm, they said.

"The team had six doses of COVID-19 vaccinations left to administer," but the doses would have expired before reaching their next destination, the department said.

"Not wanting to waste any doses, dedicated JCPH staff members began walking from car to car, offering stranded motorists a chance at receiving the vaccine," the department said. "In the end, all six doses were administered," including one to a sheriff’s office employee who had missed the mass vaccination event.

Andy Slavitt, a senior White House adviser for COVID-19, said Wednesday that any vaccine "stockpile that may have existed previously, no longer exists."

"We are taking action to increase supply and increase capacity. But even so, it will be months before everyone who wants a vaccine will be able to get one," Slavitt said. "Our practice is to maintain a rolling inventory of two to three days of supply that we can use to supplement any shortfalls in production and to ensure that we are making deliveries as committed. But we are passing doses directly along to states, very much in real time as they ordered them."

Jeff Zients, the new White House coordinator on COVID-19, said the U.S. Department of Health and Human Services will amend its rules to allow doctors and nurses who have recently retired to administer shots. They also plan to allow people licensed to vaccinate in their state to do so across state lines.

Over 23.5 million vaccine doses have been administered in the United States so far, according to the latest data from the Centers for Disease Control and Prevention.

ABC News’ Anne Flaherty and Sophie Tatum contributed to this report.

The United Kingdom now has the highest COVID-19 transmission and death rates of any country in the world, according to the World Health Organization's weekly epidemiological report released Wednesday.

With 383.1 new cases of COVID-19 per 100,000 residents, the U.K.'s transmission rate is higher than that of the United States, which decreased by 20% over the previous week to 380.6 new cases per 100,000 residents. But the UK appears to be moving in the right direction -- this week showed a 24% decrease in new cases confirmed from the previous week, the report said.

The U.K.'s COVID-19 death rate is also the world's highest, with 12.9 fatalities from the disease per 100,000 residents. The country -- which is made up of England, Scotland, Wales and Northern Ireland -- saw a 13% increase in new deaths over the previous week, according to the report.

In the U.S., the COVID-19 death rate went down by 7% to 6.5 fatalities per 100,000 residents, the report said.

As of Monday, 70 countries have detected cases of a new, more contagious variant of the novel coronavirus that was first identified in the U.K., while 31 nations have cases of another variant that first emerged in South Africa and eight countries have cases of a variant that was first identified in Brazil, according to the report.

ABC News’ Christine Theodorou contributed to this report.

Welsh authorities said Wednesday they are responding to "an ongoing incident" after a suspicious package was found at a key factory in the United Kingdom's supply chain for COVID-19 vaccines.

The plant, located in the Wrexham Industrial Estate in Wrexham, Wales, is owned by Indian biotechnology company Wockhardt, who have a partnership with British-Swedeish pharmaceutical giant AstraZeneca to manufacture its COVID-19 vaccine in the U.K.

"Wockhardt UK in Wrexham this morning received a suspicious package to site," the company said in a statement to ABC News. "All relevant authorities were immediately notified and engaged. Upon expert advice we have partially evacuated the site pending a full investigation. The safety of our employees and business continuity remain of paramount importance."

North Wales Police told ABC News in a statement: "We are currently dealing with an ongoing incident on the Wrexham Industrial Estate. The roads are currently closed and we would ask the public to avoid the area until further notice."

ABC News' Guy Davies contributed to this report.

Tampa Mayor Jane Castor signed an executive order Thursday requiring the use of face coverings at outdoor Super Bowl-related activities to help mitigate the spread of COVID-19 in the Florida city.

The order targets sites where large crowds of people are likely to congregate around the Super Bowl this weekend, with limited ability to remain socially distant from each other. They include "Event Zones" in areas of downtown Tampa and surrounding Raymond James Stadium, as well as "Entertainment Districts," including Ybor City Historic District, the South Howard Commercial Overlay District, the Central Business District and the Channel District.

Those exempt from the order include children under the age of 5, someone communicating with a hearing-impaired individual and people with existing health conditions who would be impaired by a mask.

The Super Bowl will be held on Feb. 7 between the Kansas City Chiefs and hometown Tampa Bay Buccaneers. The mask mandate is in effect now through Feb. 13. Those who violate it could be subject to a $500 fine.

The NFL had previously announced that masks will be required in the stadium unless eating or drinking.

Under a previous order still in effect, masks are required in Tampa at indoor locations outside the home when social distancing cannot be maintained.

ABC News' Will McDuffie contributed to this report