POST 55. October 26, 2020. CORONAVIRUS. The Testing Conundrum: “ It’s thus very possible to be antigen negative but P.C.R. positive, while still harboring the virus in the body..”
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I wouldn’t be surprised if a lot of people testing negative don’t even know which test they had and what that means for them.
An example of a best practice CDC recommends the following (U)
“Employees undergoing testing should receive clear information on:
the manufacturer and name of the test, the type of test, the purpose of the test, the reliability of the test, any limitations associated with the test, who will pay for the test, and how the test will be performed, and
how to understand what the results mean, actions associated with negative or positive results, who will receive the results, how the results may be used, and any consequences for declining to be tested.”
Let’s assume you’re just worried and have a choice between rapid, 15-minute tests and a PCR tests. Which should you get?
At the end of this POST see “Considerations for who should get tested?” and the link to the CDC CORONAVIRUS SELF-CHECKER
To read Posts 1-55 in chronological order, highlight and click on
The TV news shows very long lines of people in their cars, in line for Coronavirus testing. Is this “panic” testing, that is a rush to get tested without knowing which test is being given and is it the right one at the right time?
As part of my recent annual physical I had a Coronavirus test – SARS COV2 S1/S2 AB IGG. It was negative.
From “googling” I found that:
“Results are for the detection of SARS CoV-2 antibodies. IgG antibodies to SARS-CoV-2 are generally detectable in blood several days after initial infection, although the duration of time antibodies are present post-infection is not well characterized. Individuals may have detectable virus present for several weeks following seroconversion…
Negative results do not preclude acute SARS-CoV-2 infection. If acute infection is suspected, direct testing for SARSCoV-2 is necessary.
False positive results for LIAISON® SARS-CoV-2 S1/S2 IgG may occur due to cross-reactivity from pre-existing antibodies or other possible causes.” (A)
So the negative result didn’t give me any useful information. Best I could tell is I had no antibodies.
Next I tried to sort this all out….
“During a “town hall” in the White House Rose Garden aired on Thursday, the president was asked about the outbreak that’s resulted in the deaths of at least 221,000 Americans.
“With COVID, is there anything that you think you could have done differently, if you had a mulligan or a do-over of the way you handled it, what would it be?” asked Eric Bolling, the moderator for the pre-taped Sinclair Broadcasting Network event.
“Not much,” Trump shot back.
“Look, it’s all over the world, you have a lot of great leaders, a lot of smart people it’s all over the world,” he said, adding: “It came out of China. China should have stopped it.”” (R)
“President Donald Trump’s COVID-19 diagnosis is raising fresh questions about the White House’s strategy for testing and containing the virus for a president whose cavalier attitude about the coronavirus has persisted since it landed on American shores…
The Trump administration has increasingly pinned its coronavirus testing strategy for the nation on antigen tests, which do not need a traditional lab for processing and quickly return results to patients. But the results are less accurate than those of the slower PCR tests.
An early Abbott test used by the White House was plagued with problems, with multiple researchers finding that it was less accurate than rival companies’ tests in picking up positive cases. But the new antigen test the White House is using has not been independently evaluated for accuracy and reliability. Moreover, the Trump administration recently shipped antigen tests from Abbott and other manufacturers to thousands of nursing homes to test residents and staff.
Testing “isn’t a ‘get out of jail free card,’” said Dr. Alan Wells, medical director of clinical labs at the University of Pittsburgh Medical Center and creator of its test for the novel coronavirus. In general, antigen tests can miss up to half the cases that are detected by polymerase chain reaction tests, depending on the population of patients tested, he said.”” (B)
“In a flurry of memos released this week and last, the White House physician, Dr. Sean Conley, stated that President Trump no longer posed a transmission risk to others — an assessment, he noted, that was largely precipitated by the results of a bevy of “advanced diagnostics.” The declarations have helped clear Mr. Trump to return to the campaign trail, including a town-hall-style event hosted by NBC News on Thursday evening.
Outside experts have also said that Mr. Trump, who reportedly began feeling sick about two weeks ago, is probably no longer infectious. But most have based such assessments on the trajectory of the president’s symptoms — not the results of his tests.
There exists no test that can definitively determine whether someone who caught the coronavirus is still contagious. “We do not have a test for cure, and we do not have a test for infectiousness,” said Omai Garner, a clinical microbiologist at the University of California, Los Angeles.
Experts have criticized the administration’s overreliance on tests to keep the coronavirus out of Mr. Trump’s inner circle. Now, they said, the White House appears to be leaning too heavily on tests to break the president out of isolation.
Not all coronavirus tests are designed to detect the same parts of the virus. And a negative on one test does not necessarily guarantee a negative on another.
“We don’t just look at these tests in the context of ‘Coronavirus, yes or no,’” said Karissa Culbreath, a clinical microbiologist at TriCore Reference Laboratories in New Mexico. “Each test looks for a different aspect of the virus.”..
Guidelines published by the Centers for Disease Control and Prevention stipulate that symptoms — not test results — should be the primary motivator for ending a person’s isolation. People with mild or moderate Covid-19 should isolate for least 10 days after their symptoms start. That timeline could extend up to 20 days if their symptoms are severe.”(K)
“With nine days until Election Day, the White House again faces the coronavirus in its ranks.
Two top advisers to Vice President Pence have tested positive for the virus in recent days, as Pence — who tested negative on Saturday and Sunday — crisscrosses the country for rallies in swing states as he and President Trump fight to win reelection.
Marc Short, Pence’s chief of staff, tested positive for the coronavirus on Saturday.
Marty Obst, a Pence political adviser, has also tested positive for the virus, according to a person familiar with the matter who asked for anonymity on Sunday to discuss Obst’s health.
The White House says Pence will continue to campaign. He is expected to travel to North Carolina for a rally on Sunday. His wife, Karen, who also tested negative for the coronavirus on Sunday, is slated to travel to the state for a campaign event on Monday.
Short did not travel with Pence on Saturday to rallies in Lakeland and Tallahassee, Fla. Spokesman Devin O’Malley said Short “began quarantine” on Saturday and was “assisting in the contact tracing process.” Aides deemed to have had close contact with Short were pulled from the trip before departure, White House reporters who traveled with Pence were later told.
But Pence — who is considered to have had close contact with his most senior adviser — decided to “maintain his schedule in accordance with the CDC guidelines for essential personnel,” O’Malley said in a statement, noting that Pence had consulted with White House physicians.
The Centers for Disease Control and Prevention’s guidelines for essential workers who have had close contact with an infected person include wearing a mask for 14 days “at all times while in the workplace.”
Pence did not wear a mask at his outdoor rally.” (P)
“White House chief of staff Mark Meadows said Sunday that the US is “not going to control” the coronavirus pandemic, as cases surge across the country and nearly 225,000 Americans have died from the virus.
“We are not going to control the pandemic. We are going to control the fact that we get vaccines, therapeutics and other mitigation areas,” Meadows told CNN’s Jake Tapper on “State of the Union.”
At least 5 people in Pence’s orbit, including chief of staff Marc Short, are positive for coronavirus
Pressed by Tapper on why the US isn’t going to get the pandemic under control, Meadows said: “Because it is a contagious virus just like the flu.” He added that the Trump administration is “making efforts to contain it.”…
“What we need to do is make sure that we have the proper mitigation factors, whether it’s therapies or vaccines or treatments to make sure that people don’t die from this,” Meadows said.” (Q)
Confused? Read on..
“There are two different types of tests – diagnostic tests and antibody tests.
A diagnostic test can show if you have an active coronavirus infection and should take steps to quarantine or isolate yourself from others. Currently there are two types of diagnostic tests which detect the virus – molecular tests, such as RT-PCR tests, that detect the virus’s genetic material, and antigen tests that detect specific proteins on the surface of the virus.
An antibody test looks for antibodies that are made by your immune system in response to a threat, such as a specific virus. Antibodies can help fight infections. Antibodies can take several days or weeks to develop after you have an infection and may stay in your blood for several weeks or more after recovery. Because of this, antibody tests should not be used to diagnose an active coronavirus infection. At this time researchers do not know if the presence of antibodies means that you are immune to the coronavirus in the future.” (C)
“How are COVID-19 tests used?
The RT-PCR, antigen, and other tests that are being developed to detect the presence of the virus can be used for diagnostic, screening, or surveillance purposes. Diagnostic tests are focused on the experience, needs, and history of a single individual and are often used for those with COVID-19 symptoms.
Diagnostic tests may also be used to detect the virus in people without symptoms (asymptomatic individuals), typically after exposure to an infected individual. When applied to a population without regard to exposure history, the tests are considered screening or surveillance tests, which are essential tools in controlling the virus’s spread. The Food and Drug Administration (FDA) has issued standards for when each of these terms should be used and the acceptable levels of sensitivity and specificity for each.
Diagnostic tests are intended to determine with a high level of confidence whether an individual is currently infected with the virus. These tests could be used for individuals who are suspected of having COVID-19 because of their symptoms, asymptomatic individuals who have been exposed to a confirmed case of COVID-19, or individuals in particularly high-risk groups who have participated in large gatherings. Diagnostic tests must demonstrate high sensitivity and high specificity, because the intent is to use those results to make treatment decisions or quarantine recommendations for individuals. Diagnostic tests may be ordered by a health care provider or obtained directly by an individual. Diagnostic tests must be run in a lab that has been certified by the Centers for Medicare & Medicaid Services to be able to run high-complexity tests.
Screening tests are given to asymptomatic individuals for the purpose of making decisions based on that person’s test results. Examples of common uses of screening tests include testing everyone in a nursing home, testing students upon their arrival on a college campus, or requiring a negative test before admitting someone back to an office. In screening tests, all individuals are often told of their results and those individuals who test positive for the virus are typically asked to take additional steps to protect their health and those around them through quarantine or other actions.
Surveillance testing refers to broad, typically nonidentified testing of populations to inform public health actions. Examples of surveillance testing include assaying wastewater or surfaces to detect presence of the virus or testing a large number of people and looking at aggregate results to determine the prevalence of the virus in a community. In true surveillance testing, there is usually no intention to return individual results to those tested.” (D)
“How do medical researchers’ measure the accuracy of these tests?
In the realm of science, there are several ways to evaluate the reliability of tests. Some of the most common metrics are called “Accuracy”, “Precision”, “Sensitivity(Recall)”, and “Specificity”….
A confusion matrix is a table to classify if a single test was accurate or not. The table is split into four grids —
A test accurately predicts if a person has coronavirus (TP)
A test accurately predicts if the person doesn’t have the coronavirus (TN)
A test falsely predicts if a person has coronavirus (FP)
A test falsely predicts if a person doesn’t have coronavirus (FN)…
Simply, accuracy answers out of all the people in the sample, how many people’s tests showed a correct result?
Precision helps you answer, out of the people that tested positive, how many of those people actually had the coronavirus?
Sensitivity aka Recall
Sensitivity/Recall helps you answer, out of people that had coronavirus, how many of those people tested positive?
Specificity helps you answer, how well do you want the test to correctly predict that a person DOES NOT have the coronavirus?
These are all important questions medical decision-makers have to ask themselves. I’m not sure if all medical tests can be perfect, so if you start seeing news about how these tests are not working correctly. Look back at this article and try to guess what the medical researcher tried to optimize for. If I were a doctor, I would think recall is the most important one even if we have to optimize that metric at the expense of falsely positives — false test results that tell some healthy people they have the coronavirus. Also, news articles will start reporting accuracy numbers. Make sure to understand how reliable these tests are by doing some research yourself.” (E)
“In the high-stakes world of coronavirus testing, one mistake has taken center stage: the dreaded false negative, wherein a test mistakenly deems an infected person to be virus-free.
These troublesome results, experts have said, can deprive a person of treatment and embolden them to mingle with others, hastening the spread of disease.
But false negatives are not the only errors bedeviling coronavirus diagnostics. False positives, which incorrectly identify a healthy person as infected by the virus, can have serious consequences as well, especially in places where the virus is scarce….
Some rapid tests, which forgo sophisticated laboratory equipment and can deliver results in under an hour, have been criticized for returning high numbers of false positives, especially when used to screen people without symptoms. Even laboratory tests that rely on a very reliable technique called polymerase chain reaction, or P.C.R., have been known to return the occasional false positive…
A positive result on a coronavirus test sets off a cascade of consequences. According to guidelines published by the Centers for Disease Control and Prevention, people who test positive should immediately isolate for at least 10 days after their symptoms start (if they experience symptoms at all).
That is 10 days spent away from friends and family, and 10 days of potential productivity in a school or workplace lost….
False positives can also be disastrous from a treatment standpoint, said Linoj Samuel, a clinical microbiologist at Henry Ford Health System in Detroit. People with the flu or Covid-19, for example, often show similar symptoms, but may only be tested for one of them at a time. If a patient is given an incorrect diagnosis of Covid-19, that person could be deprived of treatment that could alleviate their illness, or be given a costly therapy that does little to speed their recovery.” (T)
“At the end of August, the US Food and Drug Administration (FDA) granted emergency-use approval to a new credit-card-sized testing device for the coronavirus that costs US$5, gives results in 15 minutes and doesn’t require a laboratory or a machine for processing. The United States is spending $760 million on 150 million of these tests from health-care company Abbott Laboratories, headquartered in Abbott Park, Illinois, which plans to ramp up production to 50 million per month in October…
Antigen assays are much faster and cheaper than the gold-standard tests that detect viral RNA using a technique called the polymerase chain reaction (PCR). But antigen tests aren’t as sensitive as the PCR versions, which can pick up minuscule amounts of the SARS-CoV-2 virus that causes COVID-19…
The high-sensitivity PCR tests are almost 100% accurate in spotting infected people, when they are administered properly. But such tests generally require trained personnel, specific reagents and expensive machines that take hours to provide results…
A typical antigen test starts with a health-care professional swabbing the back of a person’s nose or throat — although companies are developing kits that use saliva samples, which are easier and safer to collect than a swab. The sample is then mixed with a solution that breaks the virus open and frees specific viral proteins. The mix is added to a paper strip that contains an antibody tailored to bind to these proteins, if they’re present in the solution. A positive test result can be detected either as a fluorescent glow or as a dark band on the paper strip.
Antigen tests give results in less than 30 minutes, don’t have to be processed in a lab and are cheap to produce. Yet that speed comes with a cost in sensitivity. Whereas a typical PCR test can detect a single molecule of RNA in a microlitre of solution, antigen tests need a sample to contain thousands — probably tens of thousands — of virus particles per microlitre to produce a positive result1. So, if a person has low amounts of virus in their body, the test might give a false-negative result.” (F)
“People are getting the results of coronavirus tests in the U.S. faster than they were in the spring, but testing still takes far too long to help with effective disease control measures such as contact tracing and quarantining, according to the results of a large national survey…
Among that group, the average wait time for results was 2.7 days in September, down from four days in April, the researchers found. In addition, the proportion of people getting their results back within 24 hours increased from 23% to 37%.
While that’s an improvement, the turnaround time is still “too slow in most cases to support a successful strategy of contact tracing,” and most people are still waiting far too long, the researchers wrote…
To keep outbreaks from occurring, people who are infected need to be contacted quickly, ideally within 24-36 hours to make sure they don’t infect other people and find out who they may have come into contact with so those people can be told to quarantine and get tested.
In fact, only 56% of those who tested positive were contacted by a health worker to get contact tracing information, the researchers found…
The average person who got tested in the August and September surveys was tested within 2.5 days and waited 3.7 days for the results of the test. That means it took a total of 6.2 days between deciding on a test and receiving results, the researchers wrote.
“So even with the improvement in results, people are waiting about week. And by that point much of the harm that could occur in spreading through that person’s social network has already occurred,” Lazer says. “What you want to do is cut that to within 24 hours to 36 hours.”” (G)
“After struggling to ramp up coronavirus testing, the U.S. can now screen several million people daily, thanks to a growing supply of rapid tests. But the boom comes with a new challenge: keeping track of the results.
All U.S. testing sites are legally required to report their results, positive and negative, to public health agencies. But state health officials say many rapid tests are going unreported, which means some new COVID-19 infections may not be counted.
And the situation could get worse, experts say. The federal government is shipping more than 100 million of the newest rapid tests to states for use in public schools, assisted living centres and other new testing sites.
“Schools certainly don’t have the capacity to report these tests,” said Dr. Jeffrey Engel of the Council of State and Territorial Epidemiologists. “If it’s done at all it’s likely going to be paper-based, very slow and incomplete.”
Early in the outbreak, nearly all U.S. testing relied on genetic tests that could only be developed at high-tech laboratories. Even under the best circumstances, people had to wait about two to three days to get results. Experts pushed for more “point-of-care” rapid testing that could be done in doctors offices, clinics and other sites to quickly find people who are infected, get them into quarantine and stop the spread…
Large hospitals and laboratories electronically feed their results to state health departments, but there is no standardized way to report the rapid tests that are often done elsewhere. And state officials have often been unable to track where these tests are being shipped and whether results are being reported…
One of the challenges to an accurate count: States have wildly different approaches. Some states lump all types of tests together in one report, some don’t tabulate the quick antigen tests at all and others don’t publicize their system. Because antigen tests are more prone to false negatives and sometimes require retesting, most health experts say they should be recorded and analyzed separately. Currently only 10 states do that and post the results online, according to the COVID Tracking Project.
The federal government is allocating the tests to states based on their population, rather than helping them develop a strategy based on the size and severity of their outbreaks.
“That’s just lazy” said Dr. Michael Mina of Harvard University. “Most states won’t have the expertise to figure out how to use these most appropriately.”
Instead, Mina said the federal government should direct the limited supplies to key hot spots around the country, driving down infections in the hardest-hit communities. Keeping tighter control would also ensure test results are quickly reported.” (H)
“President Trump heralded new rapid coronavirus tests on Monday as game changers — fast, cheap and easy to use. But his administration’s deployment of the new tests to nursing homes has been plagued by poor communication, false results and a frustrating lack of planning, state leaders say.
Health officials in several states say they have been allowed no say in where the new tests are being sent and sometimes don’t know which nursing homes will receive them until the night before a shipment arrives. That has left some facilities ill-trained in how to use the tests and what to do with results. And it may be contributing to false-positive test results — when people are identified as being infected but aren’t.
The lack of federal planning also has left states with no standardized way to capture results from the new tests and include them in daily counts of infections and tests. Consequently, as the rapid tests become more widely distributed, the data and dashboards being used each day to guide the nation’s coronavirus response are becoming more inaccurate.
“This is data we need, and there’s just no way of capturing it,” Pennsylvania Health Secretary Rachel Levine said. “We need a reporting structure and not just hundreds of faxes being randomly sent from nursing homes and other facilities.”
Many states are trying to create their own way to capture and classify the new data. Epidemiologists say that piecemeal approach could result in differing data sets, making it harder to pinpoint where infections are growing most this winter when infections are expected to spike.
Fueling such problems, public health officials say, is the White House’s continued refusal to take responsibility for leading the country through the pandemic and to lay out an overarching strategy on testing, instead of repeatedly pushing that onus onto the states.
“It’s the utter lack of planning and guidance that’s creating problems,” said one state official, speaking on the condition of anonymity for fear that federal officials might retaliate by giving the state less aid. “Their approach is to just throw things over the fence to the states and to say, ‘Take this, and deal with the problem.’ ”…
Similarly, Giroir dismissed the lack of a standardized reporting system as a result of the administration moving swiftly to implement testing.
“If we wanted to get everything perfect, we would have waited months to do that. The important thing was to get these out to nursing homes now,” he said. “We’d rather save lives.”
On Monday, after receiving repeated complaints from state officials, the Trump administration said governors will be given more discretion to decide where future test shipments go…
Adding to the confusion, state officials say shipments have arrived with little guidance for those facilities about the circumstances in which the antigen tests can be used most effectively.
“There’s been little national guidance to say, ‘These are the best places to use them, this is what you do under various circumstances if you get positives and this is how to report the data,’ ” said Michael Fraser, chief executive of the Association of State and Territorial Health Officials, which represents state health departments. “We are still waiting to reach consensus on when and where health departments should use these tests.”..
That problem is likely to grow as the new rapid tests become more widely used in schools, doctor’s offices, workplaces and private businesses. Some states don’t report positive antigen test results, resulting in an incomplete portrait of the disease’s spread. Others have begun to categorize them as “probable” rather than confirmed infections.
Companies are developing antigen tests people can take at home. If they become widely available, Americans could administer the test themselves weekly or even daily, experts say. That could be a powerful weapon to stop transmission. But it would be a nightmare for recording data if a nationally standardized system is not established.
Without that data, the country would be flying blind as it navigates later stages of the pandemic, experts say…” (I)
“Twice a week, students at Williams College in Williamstown, Mass., go to a parking garage to blow their noses…
Once the testing site closes each day, Rita Coppola-Wallace , Williams’s executive director of planning, design and construction, gathers the bounty—up to 1,100 test tubes—and loads them into a waiting car. The samples are whisked off to Cambridge, Mass., 150 miles away, and processed alongside tens of thousands of others overnight at the Broad Institute of MIT and Harvard, a biomedical and genomics research center.
A primary reason many colleges in Massachusetts, New York, Maine and Vermont have experienced few coronavirus outbreaks this fall has been frequent, widespread testing. At 108 colleges and universities, that testing is being done within a carefully orchestrated system run by the Broad Institute.
The testing, along with strict, state-level quarantine orders and low levels of community spread in the region, has helped keep infection rates at schools working with Broad below 0.2%.” (J)
“However, Mara Aspinall, a biomedical diagnostics professor at Arizona State University’s College of Health Solutions, makes the case that the U.S. cannot break the chain of transmission if the coronavirus outpaces public health efforts.
What’s needed is a “paradigm shift from exquisitely accurate-but-slow tests to fast-and-good enough to quarantine,” she said. “Slow and accurate works for clinical management, but this virus is a sprinter not a marathoner. We need fast and frequent tests just to keep up.”
That approach has been endorsed by top U.S. health officials, including National Institutes of Health Director Francis Collins and federal testing czar Brett Giroir.
Earlier this month, FDA granted emergency use authorization to BD’s rapid, point-of-care coronavirus antigen test, making it only the second such diagnostic to receive a nod from the regulatory agency… (K)
When it comes to diagnostic testing, “easy, fast, and cheap” is also what the Rockefeller Foundation is advocating to bring tests to the U.S. market at a national scale needed to effectively respond to the pandemic. The organization envisions point-of-care antigen tests costing $5 to $10 per test, with same-day test results for schools and workplaces, and even faster turnaround times for mobile testing in communities.
“Today the country conducts almost zero such [screening] tests, and we need at least 25 million per week for schools, health facilities, and essential workers to function safely,” wrote Rajiv Shah, president of the Rockefeller Foundation, in the organization’s proposed national testing plan.
The U.S. will need at least another $75 billion in federal funding for testing to reach the plan’s goal of 30 million tests per week by October, including at least 25 million fast, inexpensive antigen tests for asymptomatic Americans, according to the Rockefeller Foundation…
However, the Rockefeller Foundation argues that despite testing advancements such as sample pooling, the commercial labs “cannot come close to fulfilling the nation’s screening test needs.”
Lab tests “aren’t convenient, simple, or inexpensive enough to use at the scale needed,” the report says, calling for a ramp-up in antigen testing in schools, offices and beyond.
The Rockefeller Foundation also believes it is critical for the U.S. to look beyond commercial laboratories such as LabCorp and Quest that are overwhelmed and tap the testing resources of other underutilized labs, recruiting academic and other labs.
However, time is of the essence, according to Shah. “We will soon enter a new cold and flu season with potentially 100 million cases of flu-like symptoms that stand to overwhelm our current testing capacity.”” (L)
Michael mina is a professor of epidemiology at Harvard, where he studies the diagnostic testing of infectious diseases. He has watched, with disgust and disbelief, as the United States has struggled for months to obtain enough tests to fight the coronavirus. In January, he assured a newspaper reporter that he had “absolute faith” in the ability of the Centers for Disease Control and Prevention to contain the virus. By early March, that conviction was in crisis. “The incompetence has really exceeded what anyone would expect,” he told The New York Times. His astonishment has only intensified since…
Why has testing failed so completely? By the end of March, Mina had identified a culprit: “There’s little ability for a central command unit to pool all the resources from around the country,” he said at a Harvard event. “We have no way to centralize things in this country short of declaring martial law.” It took several more months for him to find a solution to this problem, which is to circumvent it altogether. In the past several weeks, he has become an evangelist for a total revolution in how the U.S. controls the pandemic. Instead of restructuring daily life around the American way of testing, he argues, the country should build testing into the American way of life.
The wand that will accomplish this feat is a thin paper strip, no longer than a finger. It is a coronavirus test. Mina says that the U.S. should mass-produce these inexpensive and relatively insensitive tests—unlike other methods, they require only a saliva sample—in quantities of tens of millions a day. These tests, which can deliver a result in 15 minutes or less, should then become a ubiquitous part of daily life. Before anyone enters a school or an office, a movie theater or a Walmart, they must take one of these tests. Test negative, and you may enter the public space. Test positive, and you are sent home. In other words: Mina wants to test nearly everyone, nearly every day…
We must out-volume the virus, and what will matter is not the strength of any one individual ship, but the strength of the system it is part of. When the FDA regulates tests, though, it looks at the sensitivity and specificity of a single test—how well the test identifies illness in an individual—not at how the test is part of a testing regimen meant to protect society. For this reason, Mina proposes that the FDA make room for the CDC or the NIH to oversee the use of contagiousness tests. “I think the CDC could potentially create a certification process really simply. They are the public-health agency, and could say, ‘We will evaluate different manufacturers. None of these will be fully regulated by law, but here are the ones you should or should not choose.’”” (M)
The AAMC noted in July 2020, as daily cases were falling, that the United States would need to test at least 2.3 million people per day to decrease the rate of positive tests below 3%.3 Our failure to contain the spread of the virus in the first several months of the pandemic has resulted in a much higher number of tests needed now. The AAMC’s assertion that a pandemic response currently requires 9 million people per day to be tested represents an estimation of the need for immediate testing in the categories below…
Up to 800,000 diagnostic tests are needed for:
Each person who is symptomatic.
Close contacts of every positive case identified (whether symptomatic or asymptomatic).
Over 8 million screening tests are needed for:
Every person who enters a health care facility for an inpatient admission or outpatient surgery.
Routine testing of all health care providers in hospital settings.
Routine testing of first responders (law enforcement officers, paramedics, and EMTs).
Strategic sampling of residents in nursing homes and assisted living facilities.
Strategic sampling of incarcerated individuals.
Strategic sampling of residents and staff in homeless shelters.
Routine testing of every K-12 teacher.
Strategic sampling of K-12 students.
Strategic sampling of college and university students, faculty, and staff.
This is not an exhaustive list of the categories of individuals that should be routinely tested. Additional testing is needed for other essential workers and individuals such as contact tracers, delivery and retail personnel, employees of agricultural and meatpacking businesses, and public transportation employees…
Any testing approach must make a clear distinction between the number of tests needed to determine whether a specific person has COVID-19 for purposes of making further recommendations about that person’s health (diagnostic testing) and the number of tests needed to not only test asymptomatic individuals suspected of being exposed but also to test large numbers of people on a routine basis through screening and surveillance testing. As vaccination increases, those tests may shift to antibody testing to measure population-level immunity levels.
Strategic use of testing technologies means using the most appropriate tests for each purpose. In general, the more important it is to get accurate results for a single test, the more sensitive a test should be. Such tests are often, but not always, more costly and resource-intensive to run. The use of highly sensitive tests for surveillance purposes or less accurate tests for diagnostic or critical screening purposes could be misdirecting resources and could have negative impacts on individual or public health.” (N)
Fast at-home coronavirus tests could help bring the United States’ surging outbreak under control — if companies developing the tests can convince regulators that the public can be trusted to use them correctly.
Several firms are vying to be the first to market a test that Americans could buy over the counter with results delivered in minutes at a bedside or a breakfast table. That could allow people to screen themselves before heading to the office or school, relieving pressure on overburdened testing laboratories and quickly identifying new infections.
But concerns about the tests’ reliability, how consumers might react to their results and how public health departments will track them have slowed their development.
Companies formulating such tests say they won’t seek emergency authorization from the Food and Drug Administration until later this year or early next — in part because the agency wants them to prove that adults of different ages, education levels and English proficiency can successfully use their products.
Public health experts say FDA’s caution is warranted, because a test that’s unreliable or hard to use could help the virus spread. There is also a risk that many people will interpret a negative result as an all-clear; in reality, even the best test will produce some false negatives. And even a true negative does not guarantee that a person is not in the early stages of infection.
“If this was a disease that only impacted the individual, then it wouldn’t be such a problem,” said Georges Benjamin, executive director of the American Public Health Association. “The problem is that there will be a cohort of people who will take the test, find out that they are presumably negative, but they really weren’t, and go out and infect other people.”
A false negative result could be especially dangerous if “people use it to decide whether to go to parties,” said Heather Pierce, senior director for science policy at the Association of American Medical Colleges. “You’ve got infected people feeling like they have a passport to not engage in the other public health measures that we need to suppress the virus.”
False positive results are also a concern, because some people could isolate for up to two weeks, missing work or school for no reason. But that risk could be lowered with follow-up lab-based testing, and pales in comparison to at-home tests’ potential to prevent Covid-19 spread, said HHS testing czar Brett Giroir…
The agency said in July that any at-home test should be able to diagnose at least 90 percent of infections in people with and without symptoms, and should have a false positive rate of 1 percent or less. Companies must also prove to regulators that people will be able to perform the test on their own, without help from a health professional, and provide consumers clear information about when to use the tests and how to interpret the results…
FDA’s willingness to be flexible is welcome, but not enough, says Michael Mina, an epidemiologist at the Harvard T.H. Chan School of Public Health and a leading advocate for frequent, rapid testing. Mina says that at-home coronavirus testing should be used for surveillance — to detect new clusters of infection — but people should not rely solely on these tests to make medical decisions.
“We really need to have the FDA start to have a little bit of imagination with regard to how these tests are being evaluated,” Mina said. “We continue to see the FDA only approve tests through a clinical diagnostic lens.”
He said that positive results from at-home tests should be confirmed with a second test that uses a different approach to detect the virus — reducing the risk of false positives that could erode public confidence in at-home testing.
Another challenge for test developers is how to ensure results from at-home screening reach state and local health departments.
Automatic electronic reporting of results to public health authorities when an at-home test is run would be ideal, according to Mara Aspinall, a professor of biomedical diagnostics at Arizona State University. “We need to focus on as quickly as possible having that interconnectivity so that we can get an accurate count of both positives and negatives from these tests,” she said….(O)
Considerations for who should get tested (S)
People who have symptoms of COVID-19
People who have had close contact (within 6 feet of an infected person for a total of 15 minutes or more) with someone with confirmed COVID-19.
People who have been asked or referred to get testing by their healthcare provider, local
external icon or state health department.
Not everyone needs to be tested. If you do get tested, you should self-quarantine/isolate at home pending test results and follow the advice of your health care provider or a public health professional.
Coronavirus Self-Checker is a tool to help you make decisions on when to seek testing and appropriate medical care.
Take steps to protect yourself
Whether you test positive or negative for COVID-19, you should take preventive measures to protect yourself and others.
How to get a viral test
A viral test checks samples to find out if you are currently infected with COVID-19. The time it takes to process these tests can vary.
You can visit your state or local health department’s website to look for the latest local information on testing.
If you have symptoms of COVID-19 and want to get tested, call your healthcare provider first.
If you have symptoms of COVID-19 and are not tested, it is important to stay home. Find out what to do if you are sick.
What to do after a viral test
To get your test result, please check with the group that performed your test, such as your healthcare provider or health department. How long it will take to get your test results depends on the test used.
If you test positive for COVID-19, know what protective steps to take if you are sick.
Most people have mild COVID-19 illness and can recover at home without medical care. Contact your healthcare provider if your symptoms are getting worse or if you have questions about your health.
If you test negative for COVID-19, you probably were not infected at the time your sample was collected. This does not mean you will not get sick:
A negative test result only means that you did not have COVID-19 at the time of testing or that your sample was collected too early in your infection.
You could also be exposed to COVID-19 after the test and then get infected and spread the virus to others.
If you have symptoms later, you may need another test to determine if you are infected with the virus that causes COVID-19.
Updated Sept. 10, 2020
The Coronavirus Self-Checker is an interactive clinical assessment tool that will assist individuals ages 13 and older, and parents and caregivers of children ages 2 to 12 on deciding when to seek testing or medical care if they suspect they or someone they know has contracted COVID-19 or has come into close contact with someone who has COVID-19.
The online, mobile-friendly tool asks a series of questions, and based on the user’s responses, provides recommended actions and resources.
To get to the Coronavirus Self-Checker highlight and click on
then click on GET STARTED
- B.Inside the Flawed White House Testing Scheme That Did Not Protect Trump, by Rachana Pradhan and Lauren Weber and Liz Szabo, https://khn.org/news/white-house-testing-regimen-did-not-protect-the-president/
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- R.Trump says ‘not much’ he could have done differently with COVID-19, By Tamar Lapin, https://nypost.com/2020/10/21/trump-on-coronavirus-not-much-could-have-done-differently/
- T.Why False Positives Merit Concern, Too, by Katherine J. Wu, https://www.nytimes.com/2020/10/25/health/coronavirus-testing-false-positive.html?referringSource=articleShare
- U.SARS-CoV-2 Testing Strategy: Considerations for Non-Healthcare Workplaces, https://www.cdc.gov/coronavirus/2019-ncov/community/organizations/testing-non-healthcare-workplaces.html
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