A World Health Organization team emerged from their 14-day quarantine in the Chinese city of Wuhan on Thursday to begin field work in their investigation of the origins of the virus that cause the COVID-19 pandemic.

China's COVID-19 regulations required all members of the team to complete 14 days of quarantine upon their arrival. They have been taking part in virtual meetings during the quarantine period.

The researchers were seen leaving their hotel and boarding a bus on Thursday afternoon.

ABC News' Karson Yiu contributed to this report.

There were 152,478 new cases of COVID-19 confirmed in the United States on Wednesday, according to a real-time count kept by Johns Hopkins University.

Wednesday's case count is far less than the country's all-time high of 300,282 newly confirmed infections on Jan. 2, Johns Hopkins data shows.

An additional 3,943 fatalities from COVID-19 were registered nationwide on Wednesday, down from a peak of 4,466 new deaths on Jan. 12, according to Johns Hopkins data.

COVID-19 data may be skewed due to possible lags in reporting over the Martin Luther King Jr. Day holiday weekend.

A total of 25,598,062 people in the U.S. have been diagnosed with COVID-19 since the pandemic began, and at least 429,195 have died, according to Johns Hopkins data. The cases include people from all 50 U.S. states, Washington, D.C., and other U.S. territories as well as repatriated citizens.

Much of the country was under lockdown by the end of March as the first wave of pandemic hit. By May 20, all U.S. states had begun lifting stay-at-home orders and other restrictions put in place to curb the spread of the novel coronavirus. The day-to-day increase in the country's cases then hovered around 20,000 for a couple of weeks before shooting back up over the summer.

The numbers lingered around 40,000 to 50,000 from mid-August through early October before surging again to record levels, crossing 100,000 for the first time on Nov. 4, then reaching 200,000 on Nov. 27 before topping 300,000 on Jan. 2.

So far, the U.S. Food and Drug Administration has authorized two COVID-19 vaccines for emergency use -- one developed by U.S. pharmaceutical giant Pfizer and its German partner BioNTech, and another developed by American biotechnology company Moderna and the National Institute of Allergy and Infectious Diseases. More than 24 million vaccine doses have been administered nationwide, according to the latest data from the Centers for Disease Control and Prevention.

A draft request for assistance between the Federal Emergency Management Agency and the U.S. Department of Defense is under discussion that would seek as many as 10,000 service members to support administering COVID-19 vaccine shots up at 100 sites nationwide, according to a FEMA official who spoke on condition of anonymity because the details were not final.

A defense official, who also spoke on condition of anonymity, confirmed discussions are under way, but the final number of personnel is not settled.

It is also unclear what kind of active duty or National Guard mix it could be, and whether it includes National Guardsmen already helping in the vaccine effort around the country.

ABC News' Matthew Vann and Luis Martinez contributed to this report.

Dr. Anthony Fauci, chief medical adviser to U.S. President Joe Biden, told Fox News' "America Reports With John Roberts & Sandra Smith" that there’s no official recommendation yet on wearing double masks.

"The CDC doesn't officially recommend wearing double masks," Fauci said. "You know what would be a good start? If everybody wears at least one mask."

ABC News’ Anne Flaherty contributed to this report.

There have been more COVID-19 cases reported globally in the past two weeks than during the first six months of the pandemic, according to the World Health Organization.

Almost exactly a year ago, there were fewer than 100 confirmed cases of the virus outside of China, WHO Director-General Dr. Tedros Adhanom Ghebreyesus noted during a media briefing Friday. This week, the number of reported cases globally surpassed 100 million.

"Now, vaccines are giving us another window of opportunity to bring the pandemic under control. We must not squander it," Tedros said.

At the same time, Tedros warned that vaccine hoarding will be a "catastrophic moral failing" that will ultimately "keep the pandemic burning" and hinder economic recovery.

His comments come after the European Union publicly fought with AstraZeneca this week over how many doses it can expect of the drugmaker's COVID-19 vaccine. After regulators approved the vaccine Friday, the EU enacted an export restriction on doses produced in the bloc. WHO officials called the move "concerning" and part of a "worrying trend."

"Vaccine nationalism might serve short-term political goals, but it's ultimately short-sighted and self-defeating. We will not end the pandemic anywhere until we end it everywhere," Tedros said. "My message to governments is to vaccinate your health workers and older people, and share excess doses with COVAX, so other countries can do the same."

ABC News' Kirit Radia contributed to this report.