By Julie Bosman and Lauren Leatherby, The New York Times

Nearly 700,000 people across the United States have now died of the coronavirus, a milestone that few experts had anticipated months ago when vaccines became widely available to the American public.

An overwhelming majority of Americans who have died in recent months, a period in which the country has offered broad access to shots, were unvaccinated. The United States has had one of the highest recent death rates of any country with an ample supply of vaccines.

The new and alarming surge of deaths this summer means that the coronavirus pandemic has become the deadliest in American history, overtaking the toll from the influenza pandemic of 1918 and 1919, which killed about 675,000 people.

“This delta wave just rips through the unvaccinated,” said Howard Markel, a medical historian at the University of Michigan. The deaths that have followed the wide availability of vaccines, he added, are “absolutely needless.”

The recent virus deaths are distinct from those in previous chapters of the pandemic, an analysis by The New York Times shows. People who died in the last 3 1/2 months were concentrated in the South, a region that has lagged in vaccinations; many of the deaths were reported in Florida, Mississippi, Louisiana and Arkansas. And those who died were younger: In August, every age group under 55 had its highest death toll of the pandemic.

That month, Brandee Stripling, a bartender in Cottondale, Alabama, told her boss that she felt as if she had been run over by a freight train.

Stripling, a 38-year-old single mother, had not been vaccinated against the coronavirus, and now she had tested positive. Get some rest, her boss, Justin Grimball, reassured her.

“I thought she would pull through and get back to work and keep on living,” Grimball said.

Last week, he stood in a cemetery as Stripling was buried in her family plot. A pastor spoke comforting words, her children clutched one another in grief and a country song, “If I Die Young,” played in the background.

Her death came in the virus surge that gripped the country all summer, as the delta variant hurtled through the South, Pacific Northwest and parts of the Midwest.

Close to 100,000 people across the United States have died of COVID-19 since mid-June, months after vaccines were available to American adults.

The U.S. government has not closely tracked the vaccination status of everyone who has been infected with the virus, but the Centers for Disease Control and Prevention has so far identified 2,900 people who were vaccinated among the 100,000 who died of COVID since mid-June.

Vaccines have been proven highly effective in preventing severe illness and death, and a study from the CDC that was published in September found that after delta became the dominant variant, unvaccinated people were more than 10 times more likely to die of the virus than the vaccinated were. The study, which spanned from April to mid-July, used data from 10 states, New York City, Los Angeles County and King County, Washington, which includes Seattle.

The pace of death has quickened, then slowed, then quickened again over the past 18 months as the virus has rippled across America in waves.

The most recent 100,000 deaths occurred over more than three months, a considerably slower pace than when the pandemic reached its peak last winter. During that earlier surge, just 34 days elapsed between the nation’s 400,000th and 500,000th death.

By late September, more than 2,000 people on average were dying from the virus each day, a level the country has not reached since February.

But the recent deaths have left families and friends, some of whom said they had thought the pandemic was largely over, stunned and devastated. Weary doctors and nurses voiced frustration that many of the patients whose lives they were now struggling to save had shunned vaccines. Coroners, funeral home directors and clergy members were again busy consoling the grief-stricken and preparing the dead for burial.

Wayne Bright, a funeral home director in Tampa, Florida, has been handling COVID-19 deaths since the beginning of the pandemic, working long hours under difficult circumstances.

Still, this summer has been different.

About 40% of the most recent 100,000 people to die of the virus were under 65, a share higher than at any other point in the pandemic, and Bright has spent months bearing witness to what he calls “premature grief.” In one family, a father of teenagers died. A 16-year-old girl in another family lost her mother, aunt and cousin to the virus, all in quick succession.

“Now you’re dealing with people in their 30s and 40s and 50s,” he said. “These are people who, without the pandemic, they would almost certainly be alive and live full lives. It’s so much worse now than it was when the pandemic first happened. The delta variant is tremendously worse. It would be hard for me to define just how much worse it is.”

His own exhaustion runs deep. He works seven days a week and has lately been confronted with previously unimaginable problems: shortages of caskets, hospitals with full morgues and a need to schedule burials weeks into the future so cemeteries will have vaults available.

“It certainly has taken a toll,” he said. “And you just think, this just doesn’t have to be.”

The delta surge has hit working-age Americans particularly hard. Older Americans are still more susceptible to the virus but have benefited from their willingness to be vaccinated: People 65 and older, who have been among the most vulnerable to serious illness from the virus, have the highest rate of vaccination of all age groups, at 83% fully vaccinated, according to the CDC.

Vaccine mandates have begun to take effect in some states and within some companies, but only 65% of the eligible U.S. population is fully vaccinated. The nation’s vaccination campaign has been slowed by people who say they are hesitant or unwilling to get shots, amid a polarized landscape that has included misinformation from conservative and anti-vaccine commentators casting doubt on the safety of vaccines.

Vaccination rates are lower for people in their 30s, and the number of people in that age group who died of the virus in August was almost double the number who died during January, the previous record month, according to provisional counts from the CDC. More than 3,800 people in their 40s died of COVID-19 in August, compared with 2,800 in January.

Stephen Kimmel, a professor of epidemiology at the University of Florida, said younger people were particularly vulnerable to infection now because they have a relatively low rate of vaccination and are increasingly interacting with one another, leading to more opportunities to be infected. The delta variant is much more contagious than previous variants.

“If you look back when the virus first started, the mantra was, this seems to be a disease that affects older people more severely, and fortunately younger people don’t seem to get as sick,” he said. “Younger people now feel this is a virus that won’t affect them.”

In many parts of the South that weathered the worst of the summer surge, deaths from COVID-19 have only recently begun to slow down.

James Pollard, the coroner in Henry County, Kentucky, outside Louisville, said he was seeing more deaths occur at home than at any other time during the pandemic. On a recent day, he said, an ambulance was summoned to return a coronavirus patient to a hospital, but the person died before the ambulance arrived.

“The families are going through a lot of initial pain and shock and when we’re getting 20-, 30-, 40-year-old people who are passing away from it, that makes it so much more difficult,” he said. “It has more of a lasting effect than any other natural death.”

He hears a frequent refrain: family members who vow to be vaccinated after losing a relative to the disease.

The wave of delta deaths has been particularly high in rural areas of the South, where vaccination rates trail those of nearby metropolitan areas. Even though the raw number of COVID-19 deaths is higher in metropolitan areas because their populations are larger, the share of people dying of the virus in rural areas has been much greater.

The outsize impact on the South propelled Mississippi ahead of New York and New Jersey for the most coronavirus deaths relative to population throughout the pandemic. Before the delta surge, the worst-hit states had been mostly Northeastern states that suffered dire early outbreaks, as well as Arizona. But Louisiana and Alabama have become two of the five states with the highest proportion of COVID deaths.

Harold Proctor, the coroner in Floyd County, Georgia, said his office was handling twice the number of deaths compared with this time last year. At this point in the pandemic, he said, some families are so accustomed to hearing and reading about COVID-19 that they have a sense that deaths from the virus are commonplace.

“It does seem like they have more accepted that people will die of COVID now,” Proctor said.

Other families have expressed sorrow mixed with profound remorse that their dead relative was not vaccinated.

The Rev. Joy Baumgartner, a minister in Beloit, Wisconsin, presided over a recent funeral that she described as “the saddest, most grief-stricken I have ever experienced.”

The woman who died of COVID-19 was a 64-year-old church member, talented baker and frequent volunteer during group dinners on Thanksgiving. Her adult children had advised her not to receive a shot.

When they arrived at the church, Baumgartner said, the woman’s children were full of regret, despairing over their actions and searching for a rationale. “They condemned themselves,” she recalled.

“I had to hold these people in my arms in front of this urn of ashes, asking God to help them through this. It was a never-ending week of excruciating pain.”

This article originally appeared in The New York Times.