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President Joe Biden has set a goal to administer at least 100 million Covid vaccine doses during his first 100 days in office, but warned it will be very difficult to achieve herd immunity in the U.S. by the end of summer. Biden's cautious remarks — in an interview aired on Sunday ahead of the Super Bowl — are in line with the warnings of scientists and public health officials. Dr. Anthony Fauci has said at least 75% of the public would need to be inoculated against Covid-19 to achieve herd immunity. Biden also said during the interview that he was exploring new ways to quickly vaccinate more Americans.

Here are some of the biggest developments Monday:

• AstraZeneca looks to adapt Covid vaccine as South Africa suspends rollout
• Trump administration sought to suppress testing, House panel says
• CDC director says variants could cause cases, hospitalizations to rise again
• Almost 10% of the population has received at least one vaccine shot, latest CDC data shows

The U.S. is recording at least 117,000 new Covid-19 cases and at least 3,100 virus-related deaths each day, based on a seven-day average calculated by CNBC using Johns Hopkins University data.

The following data was compiled by Johns Hopkins University:

• Global cases: More than 106.40 million 
• Global deaths: At least 2.32 million
• U.S. cases: More than 27.06 million
• U.S. deaths: At least 463,470

Iowa mask mandate lifted without input from health officials

Iowa Gov. Kim Reynolds lifted the state's mask mandate without consulting the health officials in her administration, The Associated Press reported Monday.

Reynolds issued a proclamation on Friday that did away with statewide requirements to wear masks in public places indoors. Limits on public gatherings were also tossed in the proclamation.

However, state lawmakers participating in a conference call with Iowa Department of Public Health officials said they were told Reynolds did not confer with those experts before lifting those requirements.

"We asked the Iowa Department of Public Health if they had input into the governor's decision to lift the mask mandate on Friday and they said they had not," said Sen. Liz Mathis, a Democrat who participated in the meeting, according to the AP. "I just can't understand why the governor would lift that when we still have such a low percentage of vaccinations completed."

A spokesman for Reynolds' office said the announcement correlates with decreasing virus activity in Iowa.

"The governor has been consistent since the beginning of the pandemic and is following through with her commitment to dial back restrictions based on a significant decrease in COVID hospitalizations," he said in a statement.

Iowa has averaged 17 new coronavirus cases per 100,000 people between Jan. 31 and Feb. 7, according to data from The Covid Tracking Project. That's below a national average of 36 per 100,000 people.

—Fred Imbert

Millions leave work force during pandemic

Millions of Americans have left the work force due to the Covid pandemic, a trend that may reduce household income and hurt the U.S. economy.

Around 406,000 people left the work force in January, according to the Bureau of Labor Statistics. Such individuals aren't actively looking for work but may want a job. In all, more than 4 million people have left the labor force since early 2020.

People usually leave the labor force during economic recessions, but the pandemic has exacerbated the trend, according to economists. Parents have stayed home to care for children who are remote learning, and frontline workers may fear getting Covid, for example.

The trend seems to have artificially reduced the unemployment rate, since official metrics don't count such workers as unemployed.

—Greg Iacurci

UK health expert downplays threat of South African Covid strain

Professor Jonathan Van-Tam, the U.K.'s deputy chief medical officer, downplayed the threat of the South Africa Covid strain to the country, according to a report from CNBC's Matt Clinch.

"There is no reason to think the South African variant will catch up or overtake our current virus in the next few months," Van-Tam said referencing the U.K. strain first found in southeast England.

The comments come after there were concerns that the AstraZeneca-Oxford vaccine was ineffective against the South Africa strain.

Van-Tam said the "immediate threat" is the current U.K. strain that has been appearing in the country, which the vaccine has been shown to be more effective against, the report said.

—Rich Mendez

Almost 10% of the population has received at least one vaccine shot, latest CDC data shows

More than 32 million people in the U.S. have received at least one dose of a coronavirus vaccine, according to vaccination data published by the Centers for Disease Control and Prevention on Monday. That's roughly 10% of the U.S. population.

The updated data, which the CDC says is current as of 6 a.m. Monday, also shows that 9.5 million people have received both doses of either the Pfizer or Moderna vaccines, which is roughly 3% of the population including U.S. territories.

Vaccination progress varies by state. Alaska leads all states, with 15% of residents having received at least one shot, followed by West Virginia and New Mexico with 12% each. North Dakota and Connecticut both report 11% of residents have received at least one dose. Iowa, Missouri, Kansas and Alabama are lagging, according to the data, with each reporting less than 8% of their residents having received at least one vaccine shot.

—Nate Rattner

Covid testing could be solution to reopening large entertainment venues, Gov. Cuomo says

New York is hoping to bring back its entertainment venues, which have remained shuttered amid the pandemic, through extensive Covid-19 testing and capacity limitations, Gov. Andrew Cuomo said.

The coronavirus has crippled the live theater industry, especially in its central hub in New York City and on Broadway. Although Cuomo wasn't immediately able to provide a timeline for their return, the state has had success allowing some large events to take place as long as all participants provide a negative Covid-19 test.

"Opening sites with testing is something where New York wants to lead the way," Cuomo said during a press briefing.

—Noah Higgins-Dunn

New round of stimulus checks and other Covid relief could be weeks away

Americans who are eager to see more coronavirus aid from the federal government could see a package come together in the coming weeks.

But some details, particularly when it comes to eligibility for $1,400 stimulus checks, could be subject to change.

"It's not yet a done deal," said Ed Mills, Washington policy analyst at Raymond James. "But certainly there is more unification among Democrats than I have really ever seen and a sense of urgency that usually doesn't exist."

If all goes as planned, that could mean a bill could be signed into law in early March, he said.

In recent days, President Joe Biden has reaffirmed his commitment to including $1,400 direct payments in the new package.

More debate, however, is expected as to how those checks could be better targeted. Republicans have proposed a plan with lower income thresholds to qualify. Meanwhile, Sen. Bernie Sanders, I-Vt., said in an interview this weekend that he opposes dramatically lowering those caps.

Washington lawmakers are working to meet a March 14 deadline to shore up unemployment benefits. Democrats are hoping to give jobless Americans an extra $400 per week through September.

One change that likely won't make the final bill is a $15 per hour federal minimum wage, up from the current $7.25 per hour. Biden said he plans to push for a standalone bill to raise the pay rate.

—Lorie Konish

CDC director says variants could cause cases, hospitalizations to rise again

CDC Director Dr. Rochelle Walensky said new, highly contagious variants of the coronavirus are a threat to the U.S. and could reverse the recent drop in Covid-19 cases and hospitalizations.

"Please continue to wear a mask and stay six feet apart from people you don't live with. Avoid travel, crowds and poorly ventilated spaces and get vaccinated when it's available to you," she said during a White House news briefing on Covid-19.

As of Sunday, the CDC has identified 690 cases of the B.1.1.7 variant first identified in the U.K., Walensky said The agency has identified six cases of B.1.351, South African strain, as well as three cases of P.1, a variant first identified in travelers from Brazil.

Walensky said the CDC is working to find more cases of these variants, adding that the federal and state officials have increased genome sequencing about 10-fold over the last three weeks. "We are anticipating we might find more" cases in the coming weeks, she added.

–Berkeley Lovelace Jr.

Gottlieb anticipates Covid vaccine eligibility to expand widely by April

Dr. Scott Gottlieb told CNBC he expects a lack of demand for Covid vaccines to cause eligibility to be expanded by April.

"I suspect that some point in March and certainly by the end of March, we're going to have to make this generally available," Gottlieb said on "Squawk Box." "That doesn't mean everyone can go and get a vaccine on April 1, but I think everyone is going to be able to go online and get an appointment sooner than we think."

The former Food and Drug Administration commissioner said he believes limited Covid vaccine supply through February will justify keeping limited eligibility criteria in place. However, he stressed there is not an endless amount of U.S. residents who really want to be vaccinated.

"If we continue to ration it based on more and more narrow slices of the population, it's going to get harder to administer, so I think we're just going to have to open this up to general availability, which is good news," Gottlieb said.

—Kevin Stankiewicz

Disclosure: Scott Gottlieb is a CNBC contributor and is a member of the boards of Pfizer, genetic testing start-up Tempus, health-care tech company Aetion and biotech company Illumina. He also serves as co-chair of Norwegian Cruise Line Holdings' and Royal Caribbean's "Healthy Sail Panel." 

New York City restaurants can reopen indoor dining Friday, earlier than planned, Cuomo says

New York City restaurants will be allowed to reopen their indoor dining sections at 25% capacity beginning Feb. 12, a few days earlier than originally planned, Gov. Andrew Cuomo said.

The governor first announced at the end of January that the city's restaurants, which have been closed for indoor operations since mid-December, would be allowed to reopen on Feb. 14. The two-week period would give them time to prepare and alert employees, Cuomo said.

However, at a press briefing on Monday, the Democratic governor said the businesses wanted to open a few days earlier to prepare for Valentine's Day.

—Noah Higgins-Dunn

GOP Rep. Ron Wright dies of Covid-19

Republican Rep. Ron Wright of Texas has died of Covid-19 complications.

The second-term congressman, who underwent treatment for lung cancer in recent years, was 67. He announced his Covid-19 diagnosis on Jan. 21, and he and his wife, Susan, had been hospitalized while battling the virus for two weeks before his death.

Wright is the first sitting member of Congress to die of complications from the disease. GOP Congressman-elect Luke Letlow died in late December, before he took office, after contracting Covid-19.

At least 71 senators and representatives have tested positive for the disease.

Wright's seat will eventually be filled by a special election.

—Jacob Pramuk

Trump administration sought to suppress testing, House panel says

The Trump administration tried to suppress Covid-19 testing in the U.S. last year by softening guidance from the Centers for Disease Control and Prevention on who needed to be tested, a House panel said.

In August, the CDC revised its Covid-19 testing guidance to say that people who don't have symptoms "do not necessarily need a test" even if they were exposed to an infected person. The move was widely criticized by public health specialists and politicians, who said testing asymptomatic people is an important part of identifying and cutting off chains of spread.

Newly obtained emails that were released by the House Select Subcommittee on the Coronavirus Crisis show that a political appointee in the Department of Health and Human Services pushed for the change.

—Will Feuer

Citi Field mass vaccination site to open on Wednesday, New York City mayor says

New York City will open a 24-hour mass vaccination at Citi Field beginning Wednesday, which will focus on inoculating Queens residents and certain essential workers, Mayor Bill de Blasio said.

The stadium was initially scheduled to begin vaccinations by the end of January, but a lack of doses prevented the city from opening the site on time. Another mass vaccination site at Yankee Stadium opened on Friday for residents of the Bronx.

The Citi Field site will reserve half of its doses for taxi and limousine drivers, as well as food delivery workers, the mayor said at a press briefing.

—Noah Higgins-Dunn

Democrats to unveil plan to send households up to $3,600 per child

House Democrats led by Rep. Richard Neal, D-Mass., are expected on Monday to unveil their plan to send families up to $3,600 per child under the age of 6 and $3,000 per child under the age of 18 for one year in monthly installments starting in July.

The plan follows up on President Joe Biden's call to expand the Child Tax Credit, which currently provides $2,000 for children up to age 16. The legislation is expected to be included in the White House's $1.9 trillion coronavirus relief package.

While Democrats in the House and Senate are expected to support the measure, it's not clear if it will gain traction among Republicans, who have said the Covid relief package should be more targeted. Sen. Mitt Romney, R-Utah, released his own plan for a child allowance last week that was criticized by conservatives.

—Tucker Higgins

Pandemic gives a boost to Target's activewear brand

Target launched a brand of workout clothes and exercise equipment just before the pandemic struck. All in Motion has become one of the retailer's top sellers over the past year and it recently hit $1 billion in sales.

"We like to joke about this internally that it's become our guests' favorite work wear, not just workout wear," said Jill Sando, Target's chief merchandising officer for style and owned brands.

Growth of the activewear brand is just one way the big-box retailer is gaining ground in apparel and other merchandise categories as malls and competitors struggle during the global health crisis. It is one of 10 Target brands that generated $1 billion or more in sales in fiscal 2020. Four brands have hit $2 billion or more in sales over that time: kids apparel brand Cat & Jack; Good & Gather, a food and beverage line; Up & Up, a personal care and household essentials brand; and home decor brand Threshold.

In the coming months, Target will learn if that loyalty will stick — or if shoppers will return to the mall as they get Covid-19 vaccines.

—Melissa Repko

AstraZeneca looks to adapt Covid vaccine as South Africa suspends rollout

Like other vaccine makers, AstraZeneca is racing to adapt its Covid-19 vaccine in the face of new variants of the virus.

The process has become more urgent for the drugmaker after a small-scale study found that it was less effective at protecting against the more virulent strain of the virus discovered in South Africa.

The country said it would suspend the use of the shot in its vaccination program after the study, published Sunday and not yet peer-reviewed, found that the vaccine offered "minimal protection" against mild to moderate disease caused by the South African variant.

Researchers from the University of Witwatersrand and others in South Africa, and the University of Oxford, noted that the study was small, involving only around 2,000 volunteers who had an average age of 31. Oxford University said "protection against moderate-severe disease, hospitalization or death could not be assessed in this study as the target population were at such low risk."

—Holly Ellyatt

Read CNBC’s previous live coverage here:

Covid updates: Virginia reports 1st case of South African variant; NY broadens vaccine eligibility