Herd Immunity Against Covid-19 Is Unlikely in the U.S. Here's Why.Health experts say that reaching herd immunity is improbable amid hesitancy surrounding the vaccines and news of new virus variants.

Health experts said that reaching herd immunity against Covid-19 is unlikely to take place anytime soon, due to hesitancy surrounding vaccines and the spread of new virus variants.

"The virus is unlikely to go away," Rustom Antia, an evolutionary biologist at Emory University in Atlanta, toldThe New York Times. "But we want to do all we can to check that it's likely to become a mild infection."

Anthony Fauci, the top medical adviser in President Joe Biden's administration,previously saidthat around 80% of people in the U.S. need to be vaccinated to achieve herd immunity. Fauci is now stressing that herd immunity shouldn't be used "in the classic sense."

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"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," he said.

"That's why we stopped using herd immunity in the classic sense, I'm saying: Forget that for a second. You vaccinate enough people, the infections are going to go down," he added.

Still, health experts believe that the virus can be a manageable threat even if the anticipated herd immunity threshold won't be reached anytime soon. They said that the virus would continue to exist for years to come but that hospitalizations and deaths would decrease over time, according to theTimes.

Living with Covid-19 would require vaccinating the most vulnerable groups in the country, Marc Lipsitch, an epidemiologist at the Harvard T.H. Chan School of Public Health, told the newspaper. According to health experts cited byThe Times,doing so could possibly turn the virus into a seasonal and common infection, like the flu, over the long term and affect mainly young and healthy people. It would also require children to contract that virus so that a partial protection against subsequent infections could develop even if immunity weakens.

Reaching herd immunity is also unlikely because of the ease in travel restrictions amid new virus variants circulating worldwide. One of the Covid-19 variants that is currently spreading in the country, for instance, is the B.1.1.7, which was first spotted in Britain and is reportedly around 60% more transmissible, according to theTimes.

Other things that factor into achieving herd immunity include "population crowding,human behavior, sanitation and all sorts of other things," David M. Morens, a virologist and senior adviser to Dr. Fauci, told the publication.

To date, over 147 million people in the U.S. have received the first dose of either the Pfizer or Moderna vaccines and 104.7 million people are fully vaccinated, according to thelatest CDC's Covid Data Tracker.