Covid updates: Pfizer explores ways to fight new variants; 20 million Americans are fully vaccinated

President Joe Biden said Thursday there have been 50 million Covid-19 vaccines administered in the U.S., putting the administration on target for its goal of 100 million vaccinations in 100 days.

"My team has worked very hard with vaccine manufacturers, Pfizer and Moderna, to ensure we have enough supply for all adult Americans by the end of July," Biden said.

Biden said on the campaign trail he would push to have 100 million vaccines administered during his first 100 days in office. It has been 36 days since Biden's inauguration.

However, Biden warned "cases and hospitalizations could go back up with ne variants as they emerge," while urging Americans "this is not the time to relax."

—Christian Nunley

A new study from the U.S. Centers for Disease Control and Prevention found residents of a skilled nursing facility were possibly reinfected with the coronavirus, and their experiencing during the second infection was worse than the first.

The study, published in the CDC's Morbidity and Mortality Weekly Report, studied two separate outbreaks that occurred three months apart at a facility in Kentucky. Five residents tested positive during both outbreaks while testing negative multiple times in between, suggesting they were reinfected with the virus.

Those residents experienced worse symptoms the second time around compared with the first, researchers found, suggesting "the possibility that disease can be more severe during a second infection." Though Covid-19 reinfections are expected, they are generally rare, the CDC says.

"The findings of this study highlight the importance of maintaining public health mitigation and protection strategies that reduce transmission risk, even among persons with a history of COVID-19 infection,"  wrote Alyson Cavanaugh, one of the researchers who led the study.

—Noah Higgins-Dunn

Dr. Scott Gottlieb, a member of Pfizer's board, told CNBC the company is taking a dual-track approach to boosting its Covid vaccine offering against new virus variants.

The first approach is through a follow-up study that examines whether a third booster dose of its current vaccine formulation provides additional protection, Gottlieb said on "Squawk Box." While actual data is needed, Gottlieb said he expects one more dose would be helpful against the mutations.

The second method that Pfizer and its German partner BioNTech is looking at involves tweaking the vaccine's construction and delivering that modified version as a third dose, according to Gottlieb.

"What you want to do is not necessarily develop a vaccine that is particular against [B.1.351], the change that we saw in South Africa," said Gottlieb, who led the Food and Drug Administration under former President Donald Trump. "What you want to do is develop a protein sequence that is sort of a consensus sequence and bakes in enough of the changes that we've seen across the world that you have a vaccine that is protective no matter what the virus manages to do against itself."

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.

—Kevin Stankiewicz

In the second half of the year, Best Buy said it expects fewer consumers to buy home theaters and new laptops as they spend money on travel and dining out again.

The retailer exceeded Wall Street's earnings expectations for the fourth quarter, but missed on revenue expectations and reported slowing sales. It forecast an even slower rate for the coming year, with same-store sales expected to decline by as much as 2%. The high-end of its outlook shows same-store sales growing by up to 1%.

Chief Financial Officer Matt Bilunas said there will still be demand for technology, but it will take a backseat to other spending priorities as the pandemic fades.

—Melissa Repko

More than 2.5 million people around the world have died from Covid-19, according to data compiled by John Hopkins University. The United States has recorded the most fatalities so far at 506,500.

Daily global deaths are significantly lower than the pandemic peak of 17,843 deaths recorded on a single day in January. Still, more than 12,000 global deaths were recorded Wednesday, according to JHU.

—Rich Mendez

As the Covid-19 pandemic enters its second year and people continue to work and attend school through videoconferencing software like Zoom, researchers from Stanford and other schools are starting to closely study how videoconferencing affects people on a psychological level.

They're looking at whether extended eye contact can be stressful and whether interface aspects like whether the little box that shows the user, like a mirror, is unnatural.

Ultimately, there are five easy steps anyone can take to make their videoconferencing more natural, researchers say.

—Kif Leswing

Moderna said Thursday it expects to generate $18.4 billion in sales from its Covid-19 vaccine this year.

The U.S. drugmaker also said its chief medical officer, Tal Zaks, will leave the company in late September. The company said it has retained Russell Reynolds "to recruit for a new CMO with global and commercial experience."

The news comes a day after the company said it was expecting to produce at least 700 million Covid vaccine doses this year. It also said it expects to produce up to 1.4 billion Covid vaccine doses in 2022. Moderna has a deal with the federal government to deliver 300 million doses and has shipped about 55 million doses to the U.S. to date.

–Berkeley Lovelace Jr.

This week, the Biden administration announced that for two weeks starting Wednesday, the smallest businesses would have priority in applying for forgivable loans through the Small Business Administration's Paycheck Protection Program.

That was exciting news for eligible firms with fewer than 20 employees.

At the same time, the administration announced key changes to the program that won't take place until the first week of March, leaving some small business owners confused about when they should apply for loans. The changes also raised questions for certain borrowers about how much they'd be eligible for.

"It's déjà vu all over again," said Megan Gorman, an attorney and managing partner at Chequers Financial Management in San Francisco, adding that the uncertainty reminds her of the first PPP rollout in April 2020. "Are [small businesses] willing to go through a process which is going to play out as they apply?"

—Carmen Reinicke

For many Americans, the coronavirus pandemic has meant taking emergency financial actions to stay afloat.

A CNBC + Acorns Invest in You survey found that 40% of Americans have taken an emergency financial action during the pandemic, including tapping into emergency savings, borrowing money from family or friends, and visiting a food bank.

The survey was conducted by SurveyMonkey between Feb. 1-8 among a national sample of 6,182 adults.

The survey also found that those most impacted by the coronavirus pandemic were more likely to take emergency actions than others — nearly one-quarter of Black women and 17% of Latinas borrowed money from family or a friend, compared to 9% of white men.

—Carmen Reinicke

Some parts of Europe are seeing a worrying increase in new coronavirus infections as authorities grapple with fresh outbreaks and the spread of more infectious variants of the virus.

It has prompted fears of a "third wave" of Covid cases, despite the number of new coronavirus infections falling dramatically in some parts of the region.

Portugal, Spain and the U.K. and have seen infections decline in recent weeks, but this contrasts sharply with countries including France, Germany and Greece which are all seeing rises in weekly cases compared to the previous week.

—Holly Ellyatt

Vaccination data posted to the Centers for Disease Control and Prevention website on Wednesday show 20 million Americans, or 6.2% of the population, have now received two shots of a coronavirus vaccine.

About 45 million people have received one or more shots of the Pfizer or Moderna Covid-19 vaccine, equal to 13.6% of the U.S. population, according to CDC data. On Wednesday, the U.S. Food and Drug Administration's staff endorsed Johnson & Johnson's one-shot vaccine for emergency use, a key step in getting a third vaccine to market in the U.S.

—Nate Rattner

Health experts and civil liberty organizations are deeply concerned about the prospect of coronavirus vaccine passports.

It comes at a time when the U.S., the U.K. and the European Union, among others, have said they will consider whether to introduce a digital passport that will allow citizens to show they have been vaccinated against Covid-19.

Dr. Deepti Gurdasani, clinical epidemiologist at Queen Mary University of London, told CNBC via telephone that vaccine passports could inadvertently be used to provide "false assurances" to holidaymakers.

"I can see that they might be useful in the longer term, but I have several concerns about them being considered at this point in time when I think the scientific evidence doesn't support them. And there are lots of ethical concerns about them that I think are legitimate," Gurdasani said.

Meanwhile, Liberty, the U.K.'s largest civil liberties organization, has said: "These so-called passports claim they would ensure those who can prove they have coronavirus immunity can start to return to normal life. Which raises the question — what happens to everyone else?"

—Sam Meredith

One-quarter of U.S. adults have tapped into their emergency savings or borrowed money from a family or friend since the start of the pandemic, according to a new CNBC + Acorns Invest in You survey conducted by SurveyMonkey.

It is people of color who have taken the biggest hit, particularly Black women. Nearly 40% of Black females took from their savings or borrowed money, compared to 28% of Hispanic women and 27% white women.

A majority of Americans also need another stimulus payment from the government.

Almost one-third, or 29%, said they are counting on it to get by, and an additional 24% said they need it but don't think it will happen, the survey found. Fully 50% of Black Americans and 40% of Hispanics are counting on it, while 57% of Black women said the same. Another 24% of Blacks and Hispanics need it but don't believe it will occur.

The survey was conducted between Feb. 1-8 among a national sample of 6,182 adults.

—Michelle Fox and Sharon Epperson

Initial weekly jobless claims improved last week, totaling 730,000 first-time filings, as U.S. Covid cases slow and the vaccine rollout picks up steam.

Economists polled by Dow Jones expected claims to total 845,000 for the week.

The readout is still substantially higher than pre-pandemic levels, when fewer than 200,000 Americans filed for unemployment benefits each week on average. Still, 730,000 marks one of the lowest prints of the Covid era.

—Sara Salinas

Looking to holiday in Greece or Spain? You could be waiting some time. 

European leaders are expected to say on Thursday that all non-essential travel needs to remain restricted as the Covid health situation remains "serious" across the continent, according to a document seen by CNBC.

European leaders are worried about lifting restrictions at a time when Covid variants have become dominant in many member states.

"For the time being, non-essential travel needs to be restricted," they are expected to say, according to the document.

—Silvia Amaro

Pfizer and BioNTech are testing a third dose, or booster shot, of their Covid vaccine in an effort to better understand how the drug interacts with virus variants.

The companies have said they expect the two-dose vaccine to be effective against virus strains first detected in South Africa and the United Kingdom, but the additional study could mean a more robust immune response to mutations if it becomes needed.

"The rate of mutations in the current virus is higher than expected," Pfizer Chief Scientific Officer Mikael Dolsten told Reuters in an interview.

"It's a reasonable probability that we would end up with regular boosts. And for potent vaccines, it may be that you need to do a strain change every few years, but not necessarily every year."

—Sara Salinas

Moderna has completed enrollment of 3,000 participants in a clinical trial testing its Covid-19 vaccine in kids between ages 12 and 17.

Moderna's vaccine has been authorized by the Food and Drug Administration for use in people who are 18 years old and older. Clinical trial studies testing the vaccine in kids, whose immune systems can respond differently than adults, still need to be completed.

The company also said its study testing young children between ages 6 months and 11 will begin in the "near term."

–Berkeley Lovelace Jr.

Covid updates: House to pass relief bill on Friday; Biden extends national emergency declaration