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More than 1 million Oklahomans likely have COVID-19 antibodies, blood tests show

As Oklahoma nears 400,000 confirmed cases of COVID-19, the true number of people in the state whose immune systems have confronted the disease likely exceeds 1 million, according to the state’s epidemiologist.

Results from a large statewide sample of blood tests for antibodies show more than one-quarter of the state’s population of 4 million had mounted an immune response, said Dr. Jared Taylor.

That segment of the population with antibodies will contribute to the drive toward herd immunity, though the impact is hard to measure, he said.

“Theoretically, you can add together those individuals who are immune based upon natural infection plus those who are immune based on vaccination, but the reality is that’s not easy math to do,” Taylor said. “And we’ve got to be very careful in interpreting it.”

The fact that more than a quarter of the state’s population has developed antibodies may also be having a “minimal but not inconsequential” effect on confirmed case counts, which have been steadily decreasing in the last two weeks, according to Taylor.

Since the beginning of the pandemic about a year ago, public health experts have said there were many more cases of COVID-19 than were being reported through health departments.

The Centers for Disease Control and Prevention estimated last summer that the true case count was likely 10 times higher than confirmed cases showed. That estimate was based on antibody tests in some regions of the country.

As testing became more widespread, estimates of undiagnosed cases dropped.

Earlier this month, the CDC estimated that, from February to December last year, 1 in 4.2 cases was reported and that 83 million Americans had been infected out of a population of about 330 million.

Officially, the United States has reported about 26 million cases.

Researchers at Columbia University in New York recently estimated that 105 million Americans have been infected.

Taylor, Oklahoma’s epidemiologist, publishes a weekly epidemiology report that tracks several data points related to COVID-19. Among the statistics is the positivity rate — the percentage of all samples for virus detection that come back positive. A rising positivity rate means a rising rate of undiagnosed cases, but Taylor said it wasn’t possible to estimate from that data how many cases were being missed.

Antibody test results are also part of the weekly report.

Taylor’s report for the week of Jan. 15-21 shows 37% of the antibody tests in the state had been positive. That was up from 13% the week of Nov. 6-12.

The cumulative percentage of positive antibody tests was still only 9.7% in the Jan. 15-21 report. That reflects about the same percentage of the population as the test results for confirmed infections, which stood at 381,430 on Thursday.

In an interview, Taylor said the antibody test figures in the weekly report had biases and other shortcomings.

“We’ve got a larger data set that we feel like ultimately is not as biased,” he said. “It is currently showing our percent positive blood sampling at about 28%.”

The larger sample is “suggestive that — as of the first of the year — probably a quarter to a third of the state had been exposed and mounted an immune response,” Taylor said.

“Some of those individuals in that sampling would know that they were positive. They’d been diagnosed. Some of those individuals would not have known they were ever infected. They may not have gotten tested. They may have known that they were ill but they didn’t seek testing.

“We know roughly 10% of the state has been diagnosed as being infected. We know we’re missing some. How many are we missing? This would suggest that we’re diagnosing roughly a third from the beginning (of the pandemic) until now.”

Help with herd immunity?

Antibodies, Taylor said, are “an indicator that your body is responding to the infectious agent. And it usually takes a little bit of time before that emerges. So realistically when we say we’re seeing a quarter to a third of the state — 28% — positive for antibodies last week, well, that means that that number, or thereabouts, had been exposed to the virus maybe two weeks prior to that.”

The steep rise in cases, hospitalizations and deaths in Oklahoma and the rest of the country since November has made even more urgent the drive to get people vaccinated, in the hopes of reaching the point where the large majority of Americans has immunity to COVID-19.

According to some studies, people who have been infected have some immunity, though it is not clear how long it will last.

Asked whether the population of infected people aids the country’s effort to achieve herd immunity, Taylor said, “Technically, conceptually, theoretically, yes, it does.

“But where it fails is that we’re vaccinating individuals without regard to their antibody response.

“So some of those people who are getting vaccinated are also the ones who are antibody positive so you can't just say: 'Oh, we’ve got 28% of people are already antibody positive and once we vaccinate 40% of the population, we’ll be at 68%.' We’d have to filter them out.”

Also, he said, “We don’t know how high those antibody levels need to be. As I said, those antibody tests are not particularly well standardized. And so just because someone tests positive for antibodies, we don’t know if that means those antibody levels are protective enough to keep them from being infected.”

Regarding whether there has been a reduction in case counts lately because so many people have had COVID-19, Taylor said, “How much of a role is that playing? Honestly, I would say minimal at this point but not inconsequential.

“Basically, I would say the same thing about vaccination at this point. When you look at how many people we’ve vaccinated, we’re doing fabulous. We’ve set a phenomenal pace and we’re ranking very well. And yet, in the totality of our population, we’re not that high. And so I would say vaccination is having a minimal but not inconsequential impact on why we’re seeing a drop in those cases.

“And certainly we hope that over time, vaccination becomes much more important in driving down those case numbers.”

Related Photos
<strong>People wait in line to receive a COVID-19 vaccine at Ebenezer Baptist Church in Oklahoma City on  Jan. 26.  [Chris Landsberger/The Oklahoman]</strong>

People wait in line to receive a COVID-19 vaccine at Ebenezer Baptist Church in Oklahoma City on Jan. 26. [Chris Landsberger/The Oklahoman]

<figure><img src="//cdn2.newsok.biz/cache/r960-32dd66ba7cc1a7cafe939687570731d0.jpg" alt="Photo - People wait in line to receive a COVID-19 vaccine at Ebenezer Baptist Church in Oklahoma City on Jan. 26. [Chris Landsberger/The Oklahoman] " title=" People wait in line to receive a COVID-19 vaccine at Ebenezer Baptist Church in Oklahoma City on Jan. 26. [Chris Landsberger/The Oklahoman] "><figcaption> People wait in line to receive a COVID-19 vaccine at Ebenezer Baptist Church in Oklahoma City on Jan. 26. [Chris Landsberger/The Oklahoman] </figcaption></figure><figure><img src="//cdn2.newsok.biz/cache/r960-f8f3781ae134fae8ee8fdb863a7d9e0d.jpg" alt="Photo - A long-term care facility staff member, Pam Byers, receives a COVID-19 vaccination Dec. 22 as shots were rolled out for Oklahoma nursing home residents and staff at The Lodge at Brookline in Oklahoma City . [Chris Landsberger/The Oklahoman] " title=" A long-term care facility staff member, Pam Byers, receives a COVID-19 vaccination Dec. 22 as shots were rolled out for Oklahoma nursing home residents and staff at The Lodge at Brookline in Oklahoma City . [Chris Landsberger/The Oklahoman] "><figcaption> A long-term care facility staff member, Pam Byers, receives a COVID-19 vaccination Dec. 22 as shots were rolled out for Oklahoma nursing home residents and staff at The Lodge at Brookline in Oklahoma City . [Chris Landsberger/The Oklahoman] </figcaption></figure>
Chris Casteel

Chris Casteel began working for The Oklahoman's Norman bureau in 1982 while a student at the University of Oklahoma. Casteel covered the police beat, federal courts and the state Legislature in Oklahoma City. From 1990 through 2016, he was the... Read more ›

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