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.”