In this May 5, 2021, file photo, a group of friends, who said they are fully vaccinated for COVID-19, mingle on the beach in the Venice section of Los Angeles. COVID-19 deaths in the U.S. have tumbled to an average of just over 600 per day — the lowest level in 10 months — with the number of lives lost dropping to single digits in well over half the states and hitting zero on some days. Credit: Jae C. Hong / AP

COVID-19 deaths in the U.S. have tumbled to an average of around 600 per day — the lowest level in 10 months — with the number of lives lost dropping to single digits in well over half the states and hitting zero on some days.

Confirmed infections, meanwhile, have fallen to about 38,000 day on average, their lowest mark since mid-September. While that is still cause for concern, they have plummeted 85 percent from a peak of more than a quarter-million cases per day in early January.

The last time deaths were this low was early July, nearly a year ago. COVID-19 deaths in the U.S. topped out in mid-January at an average of more than 3,400 a day, just a month into the biggest vaccination drive in the nation’s history.

Kansas reported no new deaths from Friday through Monday. In Massachusetts, the Boston Herald put a huge zero on Wednesday’s front page under the headline “First time in nearly a year state has no new coronavirus deaths.”

Dr. Amesh Adalja, an infectious disease specialist at Johns Hopkins University, said that vaccinations have been crucial even as the nation struggles to reach herd immunity.

“The primary objective is to deny this virus the ability to kill at the rate that it could, and that has been achieved,” he said. “We have in effect tamed the virus.”

Nearly 45 percent of the nation’s adults are fully vaccinated, and over 58 percent have received at least one dose, according to the Centers for Disease Control and Prevention. This week, Pfizer’s vaccine won authorization for use in 12- to 15-year-olds, in a move that could make it easier to reopen the nation’s schools.

Physicians like Dr. Tom Dean in South Dakota’s rural Jerauld County are cautiously optimistic, concerned about the many people who have decided against getting vaccinated or have grown lax in guarding against infections. The county has seen just three confirmed cases in the last two weeks, according to Johns Hopkins data.

“What I’m afraid of is people believing this whole thing is over and you don’t have to worry about it any more,” Dean said. “I think complacency is our biggest threat right now.”

The encouraging outlook stands in sharp contrast to the catastrophe unfolding in places like India and Brazil.

The overall U.S. death toll stands at about 583,000, and teams of experts consulted by the CDC projected in a report last week that new deaths and cases will fall sharply by the end of July and continue dropping after that.

“I think we are in a great place, but I think India is an important cautionary tale,” warned Justin Lessler, a professor of epidemiology at John Hopkins.

“If there is a right combination of vaccine hesitancy, potentially new variants and quickly rolling back control measures that comes together, we could potentially screw this up and have yet another wave that is completely unnecessary at this point.”

Heather Hollingsworth and Stephen Groves, The Associated Press