America's latest coronavirus wave, driven by the hyper-contagious Delta variant, has left vaccinated people seething at the unvaccinated for prolonging the pandemic and ensuring the return of restrictions rather than the carefree summer they were promised.

"It's almost like they don't care about the rest of the world. They're being selfish and self-centered," Alethea Reed, a 58-year-old health care administrator in the capital Washington told AFP.

"As somebody who falls in a higher risk category, and has a spouse who falls in a very high risk category, it's really frustrating," said clinical social worker Anne Hamon, 64, adding she was upset she had not been able to convince her own brother to take the shot.

With the Centers for Disease Control and Prevention (CDC) this week recommending that vaccinated people go back to masking across much of the country, the mood was hardening among those who believe their lives were being disrupted as a result of others' choices.

Nationwide, 60.2 percent of US adults are fully vaccinated, far below the 85 to 90 percent epidemiologists now believe is necessary to contain the virus, despite the fact that the shots have been readily available for months.

The average rate masks stark regional differences that correlate closely to political preferences, with the lowest uptake in Republican voting states in the South, and the highest in the liberal Northeast.

Until recently, the conversation around vaccine holdouts had focused on alleviating their concerns, making Covid shots as easy to get as possible, and driving up demand through gift giveaways and prize draws.

Now, though, there is "a shift from understanding to impatience, and from incentives to consequences," former Republican speechwriter David Frum, who recently wrote a piece called "Vaccinated America has had enough" in The Atlantic, told AFP.

Momentum is building for mandates, with Facebook, Google and Netflix saying they will require many employees to get their vaccines.

On Thursday, President Joe Biden announced the country's millions of federal workers would need to either get vaccinated or submit to regular tests and wear masks, following similar steps taken by California and New York.

While there are many reasons for vaccine hesitancy, ranging from anti-science opposition rooted in conspiracy theories, to mistrust in the health care system stemming from historic racism, patience is wearing thin.

"There comes a point where, when you see a harmful action, the question of why it is happening becomes less important," said Frum.

"Behind every drunk driving incident, there is a personal crisis of addiction. But however sad that story is, you have to be off the road."

A woman arrives to receive her Pfizer Covid-19 vaccine at a mobile vaccine clinic hosted by Mothers in Action in Los Angeles
A woman arrives to receive her Pfizer Covid-19 vaccine at a mobile vaccine clinic hosted by Mothers in Action in Los Angeles AFP / Frederic J. BROWN

In a televised address, Biden acknowledged "many of you in the majority are frustrated with the consequences of the failure of the minority to get vaccinated," but vowed to do more to address the situation, including measures like paid vaccine leave.

Traumatized doctors who thought that hospitalized Covid cases were going to be a thing of the past are making emotional pleas.

In hard hit Alabama, physician Brytney Cobia wrote a recent viral Facebook post saying that all but one of her patients were unvaccinated.

"One of the last things they do before they're intubated is beg me for the vaccine. I hold their hand and tell them that I'm sorry, but it's too late," she said.

Matthew Heinz, a doctor in Tucson, Arizona told AFP that while cases at his hospital were far below their peak from last year, "people seem to think it's done and it's not," and he continues to see a steady stream of younger patients.

Heinz, who is also a local elected Democratic official, said he and colleagues were pushing to implement a mandate for Pima County government workers -- setting up an expected legal clash with the Republican governor Doug Ducey who has issued an order banning such measures.

There are, however, some signs of change among conservatives too.

Fox News stalwart Geraldo Rivera told his viewers this week that the unvaccinated among them were "arrogant" and "selfish," adding that opposition to vaccine passports was "caveman stuff."

Days earlier, Alabama Governor Kay Ivey, blasted vaccine holdouts for lacking "common sense," and "letting us down."

Medical sociologist Richard Carpiano of University of California, Riverside told AFP the anger of the current moment is a reassuring sign that, for all the attention grabbed by the vocally vaccine hesitant, a majority of people "believe in science, and know what they need to do."

"That kind of concern, or outrage, depending on how it gets channeled can be effective for things like mobilizing elected officials," he said.