Biden warns of danger of Delta variant as US set to miss vaccination target

Joe Biden has warned that although America has Covid-19 “on the run” the latest variant is of particular concern among those who remain unvaccinated – as the president’s goal of 70% of US adults receiving at least one shot of vaccine by the Fourth of July holiday was set to fall short.

New US cases of coronavirus jumped by 10% in the past week as the highly contagious Delta variant spreads, especially where vaccination rates are low.

“I am concerned that people who have not gotten vaccinated have the capacity to catch the variant and spread the variant to other people who haven’t been vaccinated,” Biden said on Friday.

“I’m not concerned there’s going to be a major outbreak … another epidemic nationwide. But I am concerned lives will be lost,” he added.

Celebrating strong data on jobs on Friday, Biden said: “Our economy is on the move, and we have Covid-19 on the run.”

Related: Threat to vulnerable Americans rises as Delta variant spreads

But the Centers for Disease Control and Prevention (CDC) director, Rochelle Walensky, said areas with low vaccination rates were becoming hotspots for new infections, even while the situation in the country as a whole was improving.

Nearly 25% of new US infections have been linked to the “hyper-transmissable” Delta variant, first identified in India, up from 6% in June.

As of 1 July, 66.8% of US adults have received at least one dose of vaccine. A total of 54.6% of all Americans have received one or more shot.

“We’re very, very close to that [government] goal,” said Iwan Barankay, a professor of business economics and public policy at the Wharton School of the University of Pennsylvania.

But he added: “We need to aim for higher than 70% to get us to herd immunity. We have to think clearly about who [has] not gotten vaccinated yet and understand why … we have to think about the people who are just vehemently opposed, based on their pure convictions or how they understand the evidence and science.”

Barankay said the federal funding and supply of vaccinations was already there for communities that have low vaccination rates, but that state and local governments need to carry the torch the final stretch to persuade people, with decentralized messaging, to get the shot.

“I’m actually quite impressed how many people got vaccinated, my benchmark was how many people would get a flu shot in a bad flu year,” he said, adding that is usually about 55% of people.

The US has recorded 33.7m coronavirus cases and 605,000 deaths, the highest totals in the world, according to the Johns Hopkins coronavirus resource center.

Levels of inoculation vary steeply across the US. In mid-June Vermont became the first state where 80% of eligible people have had at least one shot, and up to 66% are fully vaccinated, making it the top state in the Becker Hospital Review’s vaccine tracker, which relies on federal data.

Mississippi ranks last in the US for getting shots in arms, according to the tracker, with just under 30% of people fully vaccinated.

Mark Levine, health commissioner for Vermont, called political divisions over vaccinations “a big challenge” for Biden.

“Vermont and the north-east [are] doing extraordinarily well. Then he [Biden] has the states in the midwest not achieving those rates that have more polarization and politicization of the vaccine than we do – we just live in a very heterogeneous country,” he told the Guardian.

Levine added: “It’s really hard for the president when there’s governors in some states with low vaccination rates who are very polarizing about their vaccine position. It’s a big challenge for him.”