POST 28. May 23, 2020. CORONAVIRUS. ““You’ve got to be kidding me,”..”How could the CDC make that mistake? This is a mess.” CDC conflates viral and antibody tests numbers.

Trump: ‘If We Didn’t Do Any Testing, We Would Have Very Few Cases’

To read Posts 1-28 in chronological order, highlight and click on

CORONOVIRUS TRACKING Links to Parts 1-28

“ The Centers for Disease Control and Prevention is conflating the results of two different types of coronavirus tests, distorting several important metrics and providing the country with an inaccurate picture of the state of the pandemic. We’ve learned that the CDC is making, at best, a debilitating mistake: combining test results that diagnose current coronavirus infections with test results that measure whether someone has ever had the virus. The upshot is that the government’s disease-fighting agency is overstating the country’s ability to test people who are sick with COVID-19. The agency confirmed to The Atlantic on Wednesday that it is mixing the results of viral and antibody tests, even though the two tests reveal different information and are used for different reasons.

This is not merely a technical error. States have set quantitative guidelines for reopening their economies based on these flawed data points.” (A)

“Virginia, Texas, Georgia, and Vermont have said they’ve been adding two numbers to their totals: viral test results and antibody test results.

Viral tests are taken by nose swab or saliva sample, and look for direct evidence someone currently has Covid-19. By contrast, antibody tests use blood samples to look for biological signals that a person has been exposed to the virus in the past.

Combining the two tests’ results into one total could provide an inaccurate picture of where and when the virus spread. It could also overstate a state’s ability to test and track active infections — a key consideration as states ease coronavirus restrictions. Experts have consistently emphasized that for states to reopen safely, adequate testing and tracing is needed.

“You only know how many cases you have if you do a lot of testing,” said Elizabeth Cohen, CNN’s senior medical correspondent. “If you put the two tests together, you fool yourself into thinking you’ve done more testing than you have.”’…

Texas, Virginia and Vermont have said they’ve recognized the data issue and moved to fix it in the past few days. In Georgia, health officials said they’ve been adding antibody tests to their “total tests” number in line with methodology from the Centers for Disease Control and Prevention.” (B)

““You’ve got to be kidding me,” Ashish Jha, director of the Harvard Global Health Institute, told The Atlantic. “How could the CDC make that mistake? This is a mess.”

Viral tests — commonly referred to as PCR tests as most of them use a process known as polymerase chain reaction — are used by health professionals to determine whether or not a person is currently infected with the disease. During the pandemic, viral tests have been the most effective way of being able to diagnose a positive case of COVID-19. They are what state governments have been counting to track the number of confirmed cases of the virus they have.

Antibody, or serology, tests serve a different purpose. Unlike viral tests that are taken by nose swab or saliva sample, antibody tests examine a person’s blood to see if their immune system has created antibodies to combat COVID-19. These tests allow doctors to see if someone has previously been exposed to the virus. As the push for widespread testing in the U.S. has strengthened, antibody tests have been widely produced, many experts have balked at saying that antibodies equate to immunity from COVID-19. Serology tests are also less accurate than PCR tests, increasing the chances for a false negative.

Moreover, a negative test means different things for either test. A negative PCR test indicates to physicians that the patient isn’t currently ill with the disease. But, a negative serology test means that the patient has most likely not been exposed to or infected with COVID-19.

“The viral testing is to understand how many people are getting infected, while antibody testing is like looking in the rearview mirror. The two tests are totally different signals,” Jha told The Atlantic.” (C)

“The Atlanta-based Centers for Disease Control and Prevention and Georgia’s state health department will alter their website data to separate testing data combining antibody and diagnostic test totals.

Wednesday evening, Channel 2 Action News learned Georgia included 57,000 antibody tests in their tally of the number of Georgians who had been tested for COVID-19. That accounted for roughly 15% of the Georgians who were reportedly tested for the virus. When removed from the positive case data, it increased the rate of infected Georgians by 2%.

Simply put, the data inflated the number of Georgians who have been tested for COVID-19. That figure stands around 3%.

The inclusion of the data also offered an “apples-to-oranges” look at the testing. Antibody tests give you a window into the past. COVID-19 test results are used to determine current trends and infections…

Thursday, a CDC spokeswoman told Channel 2 investigative reporter Nicole Carr that the agency would also change its online reporting data in the coming weeks.

“Initially, when CDC launched its website and its laboratory test reporting, viral testing (tests for current infection) were far more commonly used nationwide than serology testing (tests for past infection),” the statement read. “Now that serology testing is more widely available, CDC is working to differentiate those tests from the viral tests and will report this information, differentiated by test type, publicly on our COVID Data Tracker website in the coming weeks.”..

…experts here in Georgia explained the problems that arise from the conclusions drawn when that data is mixed. This comes days after Georgia began removing antibody positives out of case counts.

“When you only count the positives from the viral test, it’s going to look like the number of people who are testing positive as a percentage of all tests is going down, when it, in fact, that may not be the case, or at least it’s exaggerating that effect,” …

“It gets more complicated than that because these tests have different accuracy levels,”… “The percentage of false positives and false negatives is going to be different with each test, so why do you would mix them together? It just clouds what you know about the situation.”…

“In the realization yesterday that that total testing number was almost impossible to interpret called, really, those numbers into question and all the policies that have been based on those numbers into question,”…“And I think rightfully raises concerns in the minds of many Georgians.”

“We really need one coordinated public health response,” he added.” (D)

“In addition, combining antibody testing with diagnostic testing could reduce the number of tests that appear to be producing positive results, lowering the overall “positivity rate.” That’s another important benchmark. The World Health Organization has recommended a positivity rate of 10% or less as a signal of whether enough testing is taking place.” (E)

“How CDC explained its actions: The inflated totals resulted from states reporting their data to the agency in that format, a CDC spokesperson told POLITICO’s Brianna Ehley. Some states are still using a simplified submission form CDC created early on that combines both types of tests, meaning they get bunched together in the federal numbers too.

The agency is now shifting states to a more detailed form that should eliminate that issue, and it plans to break out figures for the two types of tests in the next week or so.

Some questions are still unanswered. CDC wouldn’t say how long it’s been combining the two tests, and it wasn’t until Wednesday — amid questions about its practices — that CDC deleted an assertion on its website that the totals “represent only viral tests.” It’s also unclear how significantly the practice has inflated the testing totals.” (F)

““This is not an intentional misuse of information — it’s part of the fog of the infectious disease war,” said Michael T. Osterholm, a University of Minnesota professor and former state epidemiologist who was sharply critical of the disease control centers early in the pandemic. “We’ve done surveillance for cases, and now we’re all trying to do testing, and it presents unique challenges.”

Whatever the reason, the numbers are fueling Mr. Trump’s frequent — and inaccurate — boasts that the United States is doing more testing “than all other countries combined,” a claim that the fact-checking website PolitiFact has declared “pants on fire wrong.” Governors rely on testing in deciding how far to go in reopening their economies. With all 50 states moving to reopen, accurate tracking is essential.

“We’re like the blind epidemiologists trying to understand the elephant,” said Michael Levy, a professor of epidemiology at the University of Pennsylvania. Health officials, he said, need good reporting to “understand the relationship between the epidemic that we can’t see, and the data that we can see.”

Scott J. Becker, the executive director of the Association of Public Health Laboratories, said there was another reason states were tracking testing: Mr. Trump wants the numbers.

“We’ve never needed to capture test volume. That is what the White House wanted to know, how many tests were being done,” Mr. Becker said, adding, “Ordinarily this all works through the public health system, but in this response, there’s been a drive to have data numbers, at multiple levels.”” (G)

“According to The Atlantic’s COVID Tracking Project, COVID-19 testing capacity in the U.S. has more than doubled over the past month, increasing from about 147,000 tests a day in mid-April to more than 413,000 tests a day as of May 20. Simultaneously, the proportion of positive tests recorded each week fell from 10% to 6% of total tests conducted. Both trends appear encouraging at face value, but given that diagnostic and antibody tests are sometimes being lumped together, it’s impossible to know whether the data reflects reality, The Atlantic reported.

When asked about the mess-up, CDC spokesperson Kristen Nordlund said that the agency “hopes” to separate the data on their COVID Data Tracker within the next few weeks.” (H)

Prequel

POST 23. May 3, 2020. CORONAVIRUS. … what Dr. Fauci really wants,…”is just to go to a baseball game. That will have to wait. The level of testing for the virus is not adequate enough to allow for such mass gatherings.’ (K)

POST 23. May 3, 2020. CORONAVIRUS. … what Dr. Fauci really wants,…”is just to go to a baseball game. That will have to wait. The level of testing for the virus is not adequate enough to allow for such mass gatherings.’ (K)

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