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Confused about COVID-19 herd immunity in SC? Dr. Fauci says there’s ‘no magic number’

Federal health officials have a simple message for South Carolinians: Don’t worry too much about COVID-19 herd immunity right now.

Dr. Anthony S. Fauci, the nation’s top expert on infectious diseases, in a Friday interview with McClatchy argued that there’s “no magic number” for the coronavirus’ herd immunity threshold.

“What’s important to note is that we’re not going to have a moment where we say, ‘We’ve crossed this number, and therefore you can get back to exactly how things were at some point in 2019,” added Dr. Cameron Webb, senior policy adviser for COVID-19 equity at the White House.

“We’re going to go through this process of making our way back toward some version of normalcy, and I think that that’s going to be what people should expect.”

Fauci and Webb’s comments denote a recent shift in public health experts’ messaging on herd immunity.

Experts now say that the country’s most important goal should be to vaccinate as many people as possible against COVID-19.

Residents, they say, shouldn’t fret about hitting a certain percentage of vaccination coverage in the United States.

Fauci and other officials had previously pointed to herd immunity as the pandemic’s finish line. The mathematical concept has since become synonymous with “a return to normalcy.”

At one point earlier this year, Fauci estimated that 70 to 85% of Americans had to be immune to SARS-CoV-2, the novel coronavirus, to achieve herd immunity.

But on Friday he said “we don’t know what that number is.”

“The more people that get vaccinated, the less and less infection you’re going to have in the community,” said Fauci, director of the National Institute of Allergy and Infectious Diseases.

Here’s how herd immunity exactly works: Once enough people in a population are immune to SARS-CoV-2, either through vaccination or natural infection, the chance that residents will run into a person who’s infected will drop so low that the outbreak sputters out.

Some experts have recently predicted that COVID-19 herd immunity is out of reach in the United States.

Herd immunity is a complicated and ever-shifting target, experts say. Such immunity could be achieved, then lost as new coronavirus variants emerge.

The Lakes at Litchfield was one of the first senior care facilities in South Carolina to receive the Moderna COVID-19 vaccine on Monday. December 28, 2020.
The Lakes at Litchfield was one of the first senior care facilities in South Carolina to receive the Moderna COVID-19 vaccine on Monday. December 28, 2020.

Natural immunity to SARS-CoV-2 will also wane over time, much like it does for seasonal influenza viruses, affecting the percentage of residents protected against COVID-19, said Stephen Kissler, a researcher at the Harvard T.H. Chan School of Public Health, in a previous interview.

A return to normalcy, however, is not dependent on hitting a herd immunity threshold, some biostatistics experts recently told The Island Packet and Beaufort Gazette.

“We cannot eradicate COVID. ... We want COVID to become like any other disease or respiratory virus that we can deal with on a yearly basis,” said Ali H. Mokdad, a professor at the Institute for Health Metrics and Evaluation at the University of Washington, in a previous interview.

“We should focus on taming the virus and making sure we can live with it.”

Mokdad predicted that the coronavirus will become endemic, meaning its spread will wane and wax from year to year.

“This is completely up to the people,” Webb, the White House adviser, added on Friday.

Residents have to get vaccinated, he said, to move into a future with fewer public health interventions.

Roughly 42.8% of South Carolina’s 15 and up population has received at least one dose of a COVID-19 vaccine, according to the S.C. Department of Health and Environmental Control.

About 33.3% of residents 15 or older have been fully vaccinated, DHEC data show.

Note: Data in this story are current as of Friday.