US may never reach ‘herd immunity,’ experts say

Masked and unmasked pedestrians walk along the Las Vegas Strip, Tuesday, April 27, 2021, in Las Vegas. The Centers for Disease Control and Prevention eased its guidelines Tuesday on the wearing of masks outdoors, saying fully vaccinated Americans don't need to cover their faces anymore unless they are in a big crowd of strangers.(AP Photo/John Locher)
Masked and unmasked pedestrians walk along the Las Vegas Strip, Tuesday, April 27, 2021, in Las Vegas. The Centers for Disease Control and Prevention eased its guidelines Tuesday on the wearing of masks outdoors, saying fully vaccinated Americans don't need to cover their faces anymore unless they are in a big crowd of strangers.(AP Photo/John Locher) (Copyright 2021 The Associated Press. All rights reserved.)

As COVID-19 vaccination rates decline and variants become more pervasive, scientists and public health experts say the threshold needed to reach “herd immunity” is not likely any time soon — and we may never get there, according to a report from the New York Times.

With millions of Americans being vaccinated against COVID-19 every day — more than 105 million fully vaccinated as of Sunday — many are looking to the future and asking when the coronavirus pandemic will end. It’s a surprisingly difficult question that could hinge on the epidemiological concept of herd immunity.

Cindy A. Prins, Ph.D., M.P.H., a University of Florida Health infectious disease epidemiologist who is an associate professor in the UF College of Public Health and Health Professions and the UF College of Medicine, explained that herd immunity means that enough people have immunity to an illness that even if one person gets infected within the group, it’s not going to easily spread to other people because of that immunity.

MORE: UF Health researcher explains herd immunity and how it could end COVID-19 pandemic

Prins said the threshold for herd immunity is still not clear.

“You’ll see estimates upwards of about 70% of a population needing to reach immunity through either vaccination or infection before herd immunity is achieved. And then you’ll see estimates that go even higher, more toward 90%. It’s one of those things that we’re gaining a better understanding of along the way,” Prins said.

Experts worry vaccine hesitancy could stand in the way of reaching herd immunity.

“What I really worry about is that those people who are already on the fence don’t get vaccinated (and) we don’t reach herd immunity come the fall,” CNN medical analyst Dr. Leana Wen told CNN.


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