(CNN) — As the coronavirus mounts a fresh US assault, it is again tearing at the nation’s political divides in a way that multiplies its own impact and makes clear in a supposed summer of freedom that the battle against the virus is far from over.

President Joe Biden is locked in a showdown with Facebook over vaccine misinformation. His predecessor, Donald Trump, is now weighing in, linking his Big Lie over election fraud to Biden’s management of the Covid-19 crisis in a way that could brew even more of the vaccine hesitancy that is causing thousands of Americans to become infected.

Conservative pundits, would-be presidential candidates and Trump proteges have already exploited skepticism of vaccines for political gain. And new fears that a return to masks and physical distancing might be necessary in Covid hot zones, where many people have refused vaccines, are reigniting partisan fault lines. The rising political discord threatens not only to tarnish and reverse Biden’s early success in rolling out vaccines and tamping down the virus — only two weeks after the President declared partial independence from Covid-19. It could present the White House with severe challenges in the event of a full-scale next wave of infections and deaths in the coming weeks.

Even if many of the people getting sick are anti-vaccine Republicans who are not his voters anyway, any reimposed restrictions and business closures could interrupt the economic recovery that the President is relying on to boost Democrats in next year’s midterm elections. Rampant infection rates would threaten children who are not yet eligible to be vaccinated — and raise the prospect of disastrous new disruptions to schooling for a generation whose education has been irreparably interrupted. And the pernicious nature of the more infectious Delta variant is a warning of the possibility that dangerous mutations of the virus are more likely when it is widespread. So while vaccine skeptics act on the basis of individual rights, their decisions could end up affecting every American, especially if a variant emerges that is resistant to vaccines.

Rising cases in the United States come at what looks like a grim moment in the exhausting fight against the pandemic across the globe. All remaining Covid-19 restrictions are expected to be lifted in England on Monday — despite soaring infections. The government in London hopes it has broken the link between infections and hospitalizations and deaths as a result of a successful vaccine effort. In Tokyo, public opposition to the Olympic Games, which start on Friday, has been exacerbated by cases identified among a number of athletes. Much of the developing world, meanwhile, remains highly vulnerable due to a lack of vaccines.

Misinformation ‘costs lives’

The Biden administration, conscious of the public health and political risks at play, has taken aim at social media companies. US Surgeon General Dr. Vivek Murthy, appearing on CNN’s “State of the Union” Sunday, defended Biden, who bluntly said on Friday that social media networks were “killing people” by allowing vaccine misinformation to spread on their platforms. Murthy said that while Big Tech had made some efforts, the administration had also made clear to them that “it’s not enough.”

“We know that health misinformation harms people’s health. It costs them their lives,” Murthy told CNN’s Dana Bash.

Facebook reacted furiously to Biden’s call out, which possibly showed frustration on the part of the President that a significant minority of the population refuses to protect themselves with free, safe and effective vaccines.

“President Biden’s goal was for 70% of Americans to be vaccinated by July 4. Facebook is not the reason this goal was missed,” Guy Rose, Facebook’s vice president of integrity, wrote in a post on the company’s website Saturday.

He accused Biden of blaming a handful of social media networks at a time when Covid-19 cases are rising. This White House has tried to not politicize the pandemic on the grounds that doing so could worsen vaccine hesitancy. But its decision to send teams into hard-hit states to push lifesaving inoculations spurred conservative outrage and false claims that the government was trying to force people to take vaccinations against their will.

Trump, who consistently put his own political goals ahead of properly managing the crisis when he was president, weighed into the issue on Sunday, with an attack on Biden likely to incite his supporters and conservative media propagandists to follow suit.

“People are refusing to take the Vaccine because they don’t trust his Administration, they don’t trust the Election results, and they certainly don’t trust the Fake News,” Trump said in a statement.

The former President frequently lauds his own administration for the genuinely impressive feat of partnering with the private sector to produce Covid-19 vaccines in record time. But he spends far less time trying to convince his supporters to get vaccinated in a way that might help end the pandemic.

One of the senior architects of the Trump administration’s erratic anti-Covid effort, former Surgeon General Dr. Jerome Adams, has in recent days been warning that a return to masking in some areas might be necessary. He said that he now regrets advice that he and the government’s top infectious diseases expert, Dr. Anthony Fauci, gave early in the pandemic that masks were not necessary. The guidance was later superseded by evidence that masks could help prevent infections.

“I’m worried the CDC also made a similarly premature, misinterpreted, yet still harmful call on masking in the face of (the) delta variant,” Adams tweeted.

But speaking on “State of the Union,” Murthy said US Centers for Disease Control and Prevention guidance that told fully vaccinated Americans they did not need to wear masks or socially distance was meant to give flexibility to people in regions with low Covid-19 cases.

“When you see places like L.A. County and other parts of the country, where you see counties making decisions about masks that may be different from other counties, that’s OK,” Murthy said. “They’re doing that based on what’s happening in their communities, based on vaccination rates and case counts.”

But the idea of masking being reintroduced drew a swift riposte from one visible Republican, Sen. Ted Cruz of Texas, underscoring how the next phase of the pandemic is likely to be as politically contentious as previous ones.

“No. No. No. Hell NO,” Cruz, who is accusing Biden of using Facebook, Google and Twitter to censor views that he doesn’t agree with, wrote on Twitter in response to the Adams tweet.

US Surgeon General: ‘I am worried’

The effects of misinformation are increasingly apparent. Murthy painted a grave picture of what may lie in store in the US, after weeks of positive news on vaccines and a return of something like normal life was undermined by the spread of the Delta variant.

“I am worried about what is to come, because we are seeing increasing cases, among the unvaccinated in particular,” Murthy told Bash.

“And while, if you are vaccinated, you are very well protected against hospitalization and death, unfortunately, that is not true if you are not vaccinated.”

New Covid-19 cases are rising in 50 states, according to data from Johns Hopkins University. The evolution of the virus means it is now attacking younger people. Covid wards are being reopened in many hotspots. New infections are soaring in states as far apart as California and Louisiana. Almost all of the serious illness and deaths are among the unvaccinated, making it all the more important that the slowed inoculation effort picks up pace.

Former US Food and Drug Administration Commissioner Dr. Scott Gottlieb said on CBS’s “Face the Nation” that there is now “an epidemic of the unvaccinated.”

“Most people will either get vaccinated or have been previously infected, or they will get this Delta variant,” Gottlieb said, laying out a daunting scenario, and adding that the number of new cases of the disease is likely being undercounted because of the lack of testing.

The hope will be that given the fact that 48.6% of Americans are now fully vaccinated, the previous waves of deaths in the pandemic can be avoided. Twenty states — most of them run by Democrats — have fully vaccinated more than 50% of their population. But many others, especially in the conservative south, have yet to fully vaccinate even 40%, meaning the pool of potential victims of the Delta variant remains significant.

The daily average of new infections is now back up at more than 39,000 per day, after bottoming out at around 8,000 nearly a month ago. Deaths have started to tick up as well but are usually a few weeks behind infection spurts.

The-CNN-Wire™ & © 2024 Cable News Network, Inc., a Time Warner Company. All rights reserved.

Join our Newsletter for the latest news right to your inbox