The ripple of unease across Europe over rising Covid-19 case numbers manifested itself stateside this week as the threat of the Delta variant became a reality.
Testifying before the Senate health committee, the head of the Centers for Disease Control and Prevention (CDC), Dr Rochelle Walensky, told senators that Delta now accounts for 83 per cent of all Covid cases in the US.
Infections are on the rise, with the daily average of cases at 37,700 – an increase of 54 per cent from a week ago. The pattern is uneven, with a small number of states accounting for much of the jump. Unsurprisingly, areas with the lowest vaccination rates are seeing the sharpest rise in cases and account for 97 per cent of hospitalisations.
Florida alone accounted for one in five new cases last week, with infection spreading rapidly among the young and unvaccinated.
But the country is also grappling with unsettling news of fully vaccinated people reporting infections.
This week a member of House of Representatives speaker Nancy Pelosi's staff, and a White House employee, tested positive for coronavirus. Both were fully vaccinated. Press secretary Jen Psaki sought to calm nerves at the White House, noting that approximately 2,000 people work at the White House, so statistically the odd case should be expected.
“Vaccines are effective and prevent serious illness and death,” she reminded people, noting that no vaccine is 100 per cent effective. But the entry of a new phrase into the Covid lexicon – “breakthrough cases” – unnerved people in Washington, with extra demand for testing noticeable in the city.
The rebound in infection rates, even though deaths and hospitalisations remain low, seems to have had one positive effect. Several leading figures on the right appear to have had a Pauline conversion and have embraced Covid vaccines.
Fox News host Sean Hannity made a plea to his viewers this week. "Please take Covid seriously. Enough people have died. We don't need any more deaths. Research like crazy. Talk to your doctor. It absolutely makes sense for many Americans to get vaccinated." Hannity had previously dismissed Covid-19 as a hoax.
Steve Scalise, a senior Republican in Congress, who had evaded questions about whether he planned to get vaccinated, announced he had got his first shot last weekend. His home state of Louisiana has seen a steep rise in numbers in recent weeks.
“The vaccine works,” he told his local paper, noting that the rise of the Delta variant was the reason he had decided to get vaccinated.
Joe Biden referenced the change in tack at Fox News during a CNN interview on Wednesday, noting it was a "good thing". The president previously said that an endorsement from his predecessor, Donald Trump, would go a long way to encouraging vaccine take-up among conservatives (the former president and his wife Melania are believed to have been vaccinated before leaving the White House, though they did not receive the jabs in public).
Polls show that hostility to vaccines is strongest in districts that voted for Trump in last year's election, and that, like mask-wearing, vaccines have become politicised. Infectious diseases expert Dr Anthony Fauci, Biden's chief medical adviser, has emerged as something of a bogeyman for the right. Florida's governor Ron DeSantis is promoting merchandise on his website emblazoned with the words: "Don't Fauci My Florida."
The rebound in cases just as the US reopens for the summer has also renewed tensions over mask-wearing.
In May, the CDC issued guidance informing Americans that fully vaccinated people no longer had to wear masks. But the emergence of the Delta variant has called some to question if this guidance was premature.
This week Los Angeles County, one of the most populous in the country, reintroduced a mask mandate in a bid to stem the rise in cases. New York’s mayor, Bill DeBlasio, said he would not reintroduce compulsory mask-wearing, instead pledging to redouble efforts to vaccinate everyone. The CDC said there were no plans to change the federal advice.
The rise of the Delta variant may also complicate efforts to get schoolchildren back in the classroom for the new term. The US has trailed Europe in terms of in-person teaching during the pandemic, with some students deprived of in-classroom lessons for a year.
Several school districts are considering introducing obligatory mask-wearing. The nation’s leading pediatricians’ association recommended this week that everyone over the age of two, even if vaccinated, should wear masks. But states such as Texas and Arizona have already baulked at the idea. As the US prepares for the new school year, a new national argument about mask-wearing for children could be on the horizon.