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.

Forty-two people in West Virginia received the Regeneron monoclonal antibody treatment instead of the Moderna vaccine on Wednesday at a vaccination clinic hosted by staff at the Boone County Health Department, the West Virginia National Guard confirmed to ABC News.

Medical experts with the Joint Interagency Task Force do not believe there is any risk of harm to these 42 individuals. Everyone who received the monoclonal antibody has been contacted, or is in the process of being contacted, according to the West Virginia National Guard.

“The moment that we were notified of what happened, we acted right away to correct it, and we immediately reviewed and strengthened our protocols to enhance our distribution process to prevent this from happening again,” Maj. Gen. James Hoyer, Adjutant General of the West Virginia National Guard, said in a statement.

The Regeneron treatment was administered intramuscularly, like a traditional vaccination, according to the West Virginia National Guard. The Regeneron treatment, which was given FDA emergency authorization in November, is normally given as an intravenous infusion, not an intramuscular injection.

The recommendation from the Centers for Disease Control and Prevention is that for those who receive antibody treatments, "vaccination should be deferred for at least 90 days, as a precautionary measure until additional information becomes available, to avoid interference of the antibody treatment with vaccine-induced immune responses."

A West Virginia National Guard official told ABC News that "there are no concerns that this will set individuals back 90 days" and that "all 42 individuals are being offered the vaccine today."

ABC News' Arielle Mitropoulos contributed to this report.

The Centers for Disease Control and Prevention updated its guidelines for people with underlying health conditions planning to take a COVID-19 vaccine.

They CDC said that adults with underlying medical conditions -- who are more at risk of becoming seriously ill from COVID-19 -- can receive a vaccine against the virus as long as they have not had a severe allergic reaction to any of the ingredients in it.

The new guidelines state that people with HIV and those with weakened immune systems due to other illnesses or medication should be aware that information about the safety of COVID-19 vaccines for their group is not yet available. While people with HIV were included in clinical trials, more data is required to provide safety guidelines regarding the effects a vaccine could have on them. The same is true for people with autoimmune conditions.

People who have previously had Guillain-Barre syndrome or Bell’s palsy may receive a COVID-19 vaccine, though experts are still acquiring more data about their groups as well.

The CDC added that people should continue to follow coronavirus health measures -- such as wearing a mask and staying 6 feet away from others -- after receiving the shot, as experts have more to learn about the protection that COVID-19 vaccines provide under real-life conditions.