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Utah is a long way from having coronavirus herd immunity, according to University of Utah researchers examining the pandemic’s impact on the state.

Serology testing from May through part of June found that 1.2% of 6,527 individuals tested in four Utah counties had COVID-19 antibodies. When accounting for how the sampling was designed and any errors, the true rate is estimated to be 1%.

That’s “lower than reported typically in other communities around this country,” said Dr. Matthew Samore, chief of the division of epidemiology at University of Utah Health.

Some epidemiologists have said that as much as 70% of the population may need to be immune from the virus through a combination of antibodies and vaccinations to achieve what’s called herd immunity — in which a region can protect itself from a pathogen.

The researchers also found that for every coronavirus case that has been detected, another 2.4 people were infected.

The findings were presented Friday by participants in the Utah Health & Economic Recovery Outreach (HERO) project. The initiative looks at both the medical and financial impacts of the pandemic.

Both the antibody and detection statistics were celebrated as successes of sorts in Friday’s presentation.

“The low prevalence rate actually shows that our efforts did a good job,” said Dr. Angela Dunn, the state epidemiologist.

The numbers, she said, demonstrate that the physical distancing and restrictions on businesses and movement in the first two months of the pandemic proved successful in reducing the spread of the virus.

And while Utah may have detected less than 1 out of 3 coronavirus cases, that’s better than a national estimate this week from Robert Redfield, director of the Centers for Disease Control and Prevention. He said the number of infections might be 10 times higher than the 2.3 million confirmed cases.

The serology testing presented Friday covered infections from May through early June — missing the alarming spike in Utah coronavirus cases of the past two weeks. The serology and detection estimates were based on sampling in Salt Lake, Summit, Davis and Utah counties — the epicenter of the state’s outbreak.

Early in the American pandemic, Summit County was — by percentage of population — one of the hottest spots in the country for spread of COVID-19. Samore said the serology testing found 3.9% of Summit County residents had antibodies. The other three counties had rates closer to 1% or less.

Dunn has warned Utah Gov. Gary Herbert that the state needs to return its daily count of new coronavirus cases to 200 by Wednesday or consider reimposing the restrictions that existed in March and April. There were a record 676 new cases reported Friday.

The physicians and researchers who presented Friday’s data encouraged more physical distancing, wearing masks and regular hand-washing to slow the virus’s spread.

“We are not doing a good job right now,” said Andrew Pavia, chief of the division of pediatric infectious diseases at U. Health. “We need to do better.”

Herbert, local leaders and medical professional have recommended Utahns wear masks when out and about. The governor also has allowed Salt Lake and Summit counties to impose their own mask mandates.


Correction: June 26, 12:30 p.m.: An earlier version misstated the four counties sampled by researchers.