President Joe Biden said Friday that social media misinformation about Covid-19 and vaccinations is "killing people" and the White House said Facebook needs to clean up its act.

"They're killing people. The only pandemic we have is among the unvaccinated. And they're killing people," Biden told reporters at the White House, as he left for a weekend at the presidential retreat in Camp David.

The White House is turning up the pressure on social media companies to weed out what officials say is widely spread misinformation on coronavirus vaccinations.

According to US health officials, a current spike in Covid-19 deaths and illnesses around the country is almost exclusively hitting people who remain unvaccinated.

"There is a clear message that is coming through: this is becoming a pandemic of the unvaccinated," Centers for Disease Control and Prevention director Rochelle Walensky told reporters on Friday.

Many of those refusing vaccinations, despite the ease of availability throughout the United States, have said they do not trust the shots.

Skepticism is being fueled both by false posts spread by anti-vaccine activists online and by Republican politicians claiming the vaccinations are part of attempts at government control.

White House Press Secretary Jen Psaki said that Facebook and others are not doing enough to push back.

"Everybody has a role to play in making sure there's accurate information," she said.

Psaki said the White House was taking a more active approach in calling out what it sees as misinformation but insisted that Facebook in particular should react more quickly in taking down problematic posts.

Prolific fake news posters

"There's about 12 people who are producing 65 percent of anti-vaccine misinformation on social media platforms. All of them remain active on Facebook, despite some even being banned on other platforms," Psaki said, without identifying those dozen posters.

The White House has "proposed that they create a robust enforcement strategy that bridges their properties and provides transparency about the rules," she said.

The turning up of the volume against fake news immediately drew accusations from right-wing media that Biden was installing a "Big Brother" type surveillance over citizens' opinions.

Facebook, which has contracted an army of independent outside fact checkers, including from AFP, to try and clean up its content, pushed back at the White House claims.

"We will not be distracted by accusations which aren't supported by the facts," a Facebook spokesperson told AFP.

"The fact is that more than two billion people have viewed authoritative information about Covid-19 and vaccines on Facebook, which is more than any other place on the internet. More than 3.3 million Americans have also used our vaccine finder tool to find out where and how to get a vaccine. The facts show that Facebook is helping save lives. Period."

Earlier, Facebook said it was taking "aggressive action against misinformation about Covid-19 and vaccines to protect public health," and that it had removed "more than 18 million pieces of Covid misinformation," and disabled accounts spreading false information.

The CDC reported more than 33,000 new cases in the United States on Thursday, bringing the seven-day average up to 26,306, a 70 percent rise on the week before.

The seven-day average of hospital admissions is about 2,790 per day, an increase of 36 percent. And after weeks of declines, the seven-day average of deaths was 211, an increase of 26 percent.

The spikes are focused in communities with low vaccination rates and "unvaccinated Americans account for virtually all recent Covid-19 hospitalizations and deaths," said Jeff Zients, White House coronavirus response coordinator.

The new wave is driven by the Delta variant, which now accounts for more than 80 percent of new cases, according to the covSpectrum tracker.