Coronavirus updates: US reports nearly 300,000 new cases in all-time high

Sen. David Perdue, who is seeking reelection in the Georgia runoff on Jan. 5, will quarantine after Perdue was told Thursday morning that he was in "close contact with someone on the campaign who tested positive for COVID-19,” his campaign said in a statement.

Both Perdue and his wife, Bonnie, tested negative for the coronavirus Thursday and have been tested regularly throughout the campaign, according to the statement.

Perdue's wife will also quarantine, the statement said.

ABC News' Quinn Scanlan contributed to this report.

The World Health Organization has approved the Pfizer/BioNTech vaccine for "Emergency Use Listing," which it says “opens the door for countries to expedite their own regulatory approval processes to import and administer the vaccine.”

Emergency Use Listing also lets UNICEF and the Pan-American Health Organization "procure the vaccine for distribution to countries in need,” the WHO said.

“This is a very positive step towards ensuring global access to COVID-19 vaccines. But I want to emphasize the need for an even greater global effort to achieve enough vaccine supply to meet the needs of priority populations everywhere,” Dr Mariângela Simão, WHO assistant director-general for Access to Medicines and Health Products, said in a statement. “WHO and our partners are working night and day to evaluate other vaccines that have reached safety and efficacy standards. We encourage even more developers to come forward for review and assessment.”

ABC News' Kirit Radia contributed to this report.

In Yakima, Washington, 145 employees at a Costco have tested positive for COVID-19, the Yakima Health District said.

The outbreak was first announced on Christmas Eve with 68 staff members testing positive. Once testing was expanded to all employees, the number grew to 145.

“After reviewing the number of cases, and the timeline in which they were identified, there is evidence to show that this sharp increase in cases mimics the type of activity that happens after some sort of super- spreader event where multiple people are infected at the same time,” the health district said.

“For Costco specifically, site-wide testing was recommended given the large number of infected employees. When site-wide testing is recommended, the organization provides testing to all employees, regardless of whether they were identified as an initial close contact to a positive COVID-19 case or not,” the health district continued. “Costco will continue to provide on-going site-wide testing for their employees moving forward to monitor the outbreak.”

ABC News' Matt Fuhrman contributed to this report.

Hard-hit California reported 428 new deaths on Thursday, following Wednesday’s daily record high of 432 fatalities.

The Golden State’s death toll is now over 25,000.

ABC News' Matt Fuhrman contributed to this report.