Coronavirus updates: Herd immunity by fall 'ambitious,' says surgeon general nominee

Dr. Anthony Fauci, the nation's top expert on the coronavirus pandemic, said rejoining the World Health Organization was "very important" and that the country's withdrawal from the United Nations agency "was very disconcerting to everybody."

"It's going to be really very important. When you're dealing with global pandemic, you have to have an international connectivity, and for us to not be in the WHO was very disconcerting to everybody, all the member countries including the health officials here in the United States," Fauci, director of the National Institute of Allergy and Infectious Diseases, told ABC News' Michael Strahan in an interview Thursday on "Good Morning America."

Earlier Thursday, Fauci announced via video link to the WHO's executive board in Geneva that the United States will remain a member, will fulfil its financial obligations to the organization and will stop reducing its staff there.

Fauci also told the board that U.S. President Joe Biden will issue a directive Thursday that shows the country's intent to join the COVAX Facility, a global initiative to ensure rapid and equitable access to COVID-19 vaccines for all countries regardless of income.

The announcement came just hours after Biden, who was sworn-in Wednesday, signed an executive order reversing former President Donald Trump's decision to withdraw from the WHO. Trump had accused the organization of failing to correctly respond to the coronavirus pandemic and of allegedly giving too much power to China.

"The official announcement that we are rejoining, we're going to live up to our financial commitments and a whole bunch of other things, it was really a very good day. I mean, the response I'm getting from my colleagues all over the world is really very refreshing," Fauci said on "GMA."

Fauci, who is Biden's chief medical adviser on the coronavirus pandemic, said he will meet with the president later Thursday to brief him on the U.S. outbreak and the vaccine situation.

"The president has made this his top priority," he said. "His goal is to get 100 million people vaccinated within the first 100 days of his presidency. I mean, I feel fairly confident that that's going to be not only that but maybe even better."

Fauci said the contractual agreements the U.S. has made to procure COVID-19 vaccines will help meet that goal, along with new initiatives to open community vaccination centers and make the vaccines available in pharmacies. He said Biden may also use the Defense Production Act "wherever he needs it." The 1950 wartime law requires private companies to prioritize any product orders from the federal government over others.

"As he says, he's going to do everything that he needs to do to make sure we have a successful roll out of the vaccines, get it into peoples arms and get as many people vaccinated as we possibly can," Fauci said. "I think we can look forward to having more companies supplying vaccines in addition to the two now that are doing it, namely Moderna and Pfizer."

Fauci said an RNA virus like the novel coronavirus can be expected to mutate but some of the new strains that have emerged are "concerning" and must be followed "very, very carefully."

"There are some concerning variants, there's one in the U.K. and we have that right now in the United States. It appears to be transmitted more efficiently, it doesn't appear to be more virulent," he said. "We're looking very carefully to make sure that our vaccines that we're distributing and putting into peoples arms [are] going to continue to protect against those variants."

Some 900,000 workers in the United States lost their jobs and filed for unemployment insurance last week, the U.S. Department of Labor said Thursday. 

This is a decrease of 26,000 jobless claims compared to the previous week.

The Department of Labor said Thursday that nearly 16 million people were still claiming some form of unemployment benefits through all government programs as of the week ending Jan. 2. During the same week last year, that figure was 2.2 million. 

The coronavirus pandemic as well as measures to curb the virus’ spread have gutted the U.S. labor market. Before the pandemic hit, in February 2020, the national unemployment rate was at a half-century low of 3.5%. As of last month, the unemployment rate was 6.7%. 

ABC News’ Catherine Thorbecke contributed to this report.

The U.S. Centers for Disease Control and Prevention now projects that the country will have recorded up to 508,000 COVID-19 deaths by mid-February.

The CDC on Wednesday published its latest national ensemble forecast, which predicts that 17,000 to 29,300 new fatalities from COVID-19 will likely be reported in the week ending Feb. 13. A total of 465,000 to 508,000 deaths from the disease are projected to be reported nationwide by this date.

Last week's national ensemble forecast predicted there would be a total of 440,000 to 477,000 COVID-19 deaths reported nationwide by Feb. 6.

The United States will remain a member of the World Health Organization, Dr. Anthony Fauci, the nation's top infectious disease expert, announced Thursday.

Fauci, director of the U.S. National Institute of Allergy and Infectious Diseases, made the announcement via video link to the WHO's executive board in Geneva, a day after Joe Biden was sworn-in as the 46th president of the U.S.

"I am honored to announce the United States will remain a member of the World Health Organization," Fauci told the board Thursday, adding that the U.S. will also "fulfil its financial obligations" to the WHO and stop reducing its staff at the United Nations agency..

Fauci, who is Biden's chief medical adviser on the coronavirus pandemic, also announced that the president will issue a directive Thursday that shows the country's intent to join the COVAX Facility, a global initiative to ensure rapid and equitable access to COVID-19 vaccines for all countries regardless of income.

Within hours of becoming president, Biden had signed an executive order reversing former President Donald Trump's decision to withdraw from the WHO. Trump had accused the organization of failing to correctly respond to the coronavirus pandemic and of allegedly giving too much power to China.