As many as 100,000 new Covid-19 deaths in the US by December is “predictable but preventable”, the leading US infectious diseases expert said on Sunday, as dozens of states reported rapidly increasing fatalities.

Amid resistance in some states to public health measures and mandates, the Delta variant of the virus has pushed up deaths in 14 states by more than 50% in a week, and by at least 10% in 28 more, according to Johns Hopkins University. Those figures follow a dire warning from the University of Washington that tens of thousands more could die, with a daily peak of 1,400 by mid-September.

On Sunday, Johns Hopkins put the US death toll from Covid-19 at almost 637,000.

“What is going on now is both entirely predictable and entirely preventable,” Dr Anthony Fauci, head of the National Institute of Allergy and Infectious Diseases and chief medical adviser to President Joe Biden, told CNN’s State of the Union.

“We know we have the wherewithal with vaccines to turn this around, and the reason the numbers are so alarming is that we have about 80 million people in this country who are eligible to be vaccinated who are not yet vaccinated.

“We could turn this thing around and we can do it efficiently and quickly if we could just get those people vaccinated. It’s so important that people in this crisis put aside any ideological and political differences and just get vaccinated.”

Vaccine hesitancy is decreasing, figures show, with an average of about 900,000 shots being administered each day in the US, up 80% in a month. This week, Biden hailed full Federal Drug Administration (FDA) approval of the Pfizer vaccine for those 16 and older as “a key milestone” in the coronavirus fight.

But experts say that the rate must increase further, and the public needs to continue social distancing and mask wearing, if the situation is to improve.

“We can save 50,000 lives simply by wearing masks,” said Ali Mokdad, professor of health metrics sciences at the University of Washington. “That’s how important behaviours are.”

On NBC’s Meet the Press, Fauci said the administration would stick to its plan to offer booster shots beginning next month to those vaccinated eight months ago. Some countries, such as Israel, are offering boosters after five months, after reviewing data suggesting protection begins to decrease in a shorter timeframe.

“We’re still planning on eight months,” Fauci said. “That was the calculation we made [and] this roll out will start on the week of 20 September.

“That’s the plan that we have, but we are open to data as they come in. This will have to go through the FDA process and then the advisory committee on immunisation practices that advises the Centers for Disease Control and Prevention [CDC]. So right now, we’re sticking with eight but we’re totally open to any variation in that based on the data.”

Asked if he believed coronavirus would become endemic, Fauci said: “In some respects, yes, but mostly no.

“We have within our power the wherewithal to really suppress this outbreak, at least in the US. We want to do it globally, and we’re playing an important role in that. But with regard to the United States, if we really got the overwhelming majority of those 80 million vaccinated, you would see a dramatic turnaround in the dynamics of the outbreak. So, it really is up to us. We have the power to do it. We just need to do it.”

Hospitals around the US are struggling to manage a significant increase in admissions due to Covid-19, the vast majority of unvaccinated patients.

“We have enough people dying that there is no room to put these bodies,” Alabama’s state health officer, Dr Scott Harris, said on Friday. “We are really in a crisis situation, I don’t know how much longer we’re going to be able to do this.”

In Mississippi, which on Sunday was under the threat from Hurricane Ida, the Republican governor, Tate Reeves, said he believed religion helped explain vaccine hesitancy.

“I’m often asked by some of my friends on the other side of the aisle about Covid, and why does it seem like folks in Mississippi and maybe in the mid-south are a little less scared, shall we say,” Reeves told a Republican fundraiser, according to the Daily Memphian.

“When you believe in eternal life, when you believe that living on this earth is but a blip on the screen, then you don’t have to be so scared of things. God also tells us to take necessary precautions, and we all have opportunities and abilities to do that and we should all do that. I encourage everyone to do so.”