(WTRF) — Scientist and public health experts believe that herd immunity can’t be reached in the U.S. due to the dropping COVID-19 vaccination rates, according to a report from The New York Times.

According to the experts who spoke with the Times, the coronavirus will more likely become a constant but manageable threat in the U.S. for several more years.

“The virus is unlikely to go away,” Emory University evolutionary biologist Rustom Antia told the newspaper. “But we want to do all we can to check that it’s likely to become a mild infection.”

Herd immunity occurs when a sufficient percentage of the population becomes immune to infection. Dr. Anthony Fauci, the nation’s top infectious disease expert, has previously estimated 70% to 85% of the U.S. population needs to be vaccinated to achieve herd immunity.

In addition, new COVID-19 strains are developing at a rate too rapid for herd immunity to be achieved anytime soon, the newspaper reported.

Fauci has now recognized a shift in thinking by experts.

“People were getting confused and thinking you’re never going to get the infections down until you reach this mystical level of herd immunity, whatever that number is,” Fauci said to the Times, adding this is why he stopped using the term “herd immunity.”

Experts told the Times if herd immunity isn’t possible, the most important goal will be to lower the rate of hospitalizations and deaths.

The total number of lives lost to COVID-19 in the U.S. has eclipsed 575,000, though deaths have plummeted to an average of about 670 per day from a peak of around 3,400 in mid-January.

According to the Centers for Disease Control and Prevention, 39% of the nation’s adult population has been fully vaccinated, and over 55% of adults have received at least one dose, up from 30% a month ago.

However, about 8% of those who have gotten one dose of either the Pfizer or Moderna vaccine have not returned for their second shot, officials said. Fauci said it is important to complete the course to gain maximum protection against the virus.

The Associated Press contributed to this report.