Abstract from April 28th letter from New Jersey Department of Health on serologic testing for Coronavirus.
“Currently, these tests may be useful to determine the prevalence of COVID 19 in a population or to identify individual patients who may be candidates to donate plasma for therapeutic purposes. There is, of course, also great interest in identifying individuals who may be immune to SARS-CoV-2 due to previous infection. However, due to the lack of current evidence that detection of SARS-CoV-2 antibody on any serologic test is indicative of durable immunity, and that false positives can occur with any of these serologic tests, they should not be used for this purpose at this time. Additionally, serologic tests do not have a role in diagnosing acute infection in symptomatic individuals since antibody responses to infection may take days to weeks to be detectable. A negative serologic test does not rule out active infection and a positive serologic test may reflect prior infection with a human coronavirus other than SARS-CoV-2. A positive test is not indicative of immunity and should not be used for return-to-work decisions.”
to read Posts 1-23 in chronological order, highlight and click on
“Some antibody tests, which check for prior Covid-19 infection, had high rates of false positives in screenings performed by a consortium of California laboratories, according to a recently released report.
A false positive means someone would be told they’d already had coronavirus when they had not – a potential danger as people could then think they were immune to the virus when they’re actually still vulnerable.
Of the 12 antibody tests that were studied by the COVID-19 Testing Project, one of the tests gave false positives more than 15% of the time, or in about one out of seven samples. Three other tests gave false positives more than 10% of the time.
“That’s terrible. That’s really terrible,” said Dr. Caryn Bern, one of the authors of the study that looked at the 12 tests. She said while it’s unrealistic to think all tests will be 100% accurate all the time, their false positive rates should be 5% or lower, or ideally 2% or lower.
“This was a real wake up call for me. We’re not at the point where any of these tests can be used reliably,” added study coauthor Dr. Alexander Marson. “There’s a big danger in relying on them at all, but we hope we get to a point soon where we can rely on these tests.” …
Of the 12 tests in the California review, only one company has this FDA stamp of approval. That’s a test by Mount Sinai Laboratory in New York City, which the California group tweaked to use in their own lab.
That test got only one false positive out of 108 blood samples…
The California researchers obtained as many tests as possible, but so far have been unable to screen antibody tests by large test makers such as Roche and Abbott, because they require proprietary instruments to run the tests, which the California tests did not have.
They hope to continue screening more antibody tests to see if they work but warned that even if a reliable test shows you have antibodies, doctors still don’t know what that means. Having antibodies could indicate you’re immune and won’t get infected a second time or it could indicate you have no immunity at all. It could also mean something in between — for example, that you have some limited immunity for a period of a few months.
“We have this huge knowledge gap,” Bern said. “That’s the most important message.” (A)
“The Food and Drug Administration has allowed about 90 companies, many based in China, to sell tests that have not gotten government vetting, saying the pandemic warrants an urgent response. But the agency has since warned that some of those businesses are making false claims about their products; health officials, like their counterparts overseas, have found others deeply flawed.
Tests of “frankly dubious quality” have flooded the American market, said Scott Becker, executive director of the Association of Public Health Laboratories. Many of them, akin to home pregnancy tests, are easy to take and promise rapid results.
And the federal guidance that does exist is so confusing that health care providers are administering certain tests unaware that they may not be authorized to do so. Some are misusing antibody test results to diagnose the disease, not realizing that they can miss the early stages of infection.
“People don’t understand how dangerous this test is,” said Michael T. Osterholm, an infectious disease expert at the University of Minnesota. “We sacrificed quality for speed, and in the end, when it’s people’s lives that are hanging in the balance, safety has to take precedence over speed.”
Even as government agencies, companies and academic researchers scramble to validate existing tests and create better ones, there are doubts they can deliver as promised. Most tests now available mistakenly flag at least some people as having antibodies when they do not, which could foster a dangerously false belief that those people have immunity.
And even if the tests do improve, their availability could be hampered by the same manufacturing shortages that have prevented the Covid-19 diagnostic tests from scaling up adequately.
As President Trump presses to reopen the country and several states are considering lifting lockdowns in the next few weeks, widespread screening is considered critical. On Friday, Mr. Trump cheered the F.D.A.’s emergency approval of some antibody tests, saying they would support efforts to get Americans back to work “by showing us who might have developed the wonderful, beautiful immunity.”” (B)
“Testing for the coronavirus has been very much in the news. The first and most urgent focus is on increasing access to tests to diagnose people with current infections. But now other tests are appearing as well. Antibody tests, which can identify people with signs of past infection, are starting to be available. And a third type of test is on the way.
Here’s a quick guide to sorting out the pluses and minuses to each type of test.
Diagnostic or PCR test
What it does: Doctors use this test to diagnose people who are currently sick with COVID-19. This is the one we’ve been hearing so much about.
What it does: Antibody tests identify people who have previously been infected with the coronavirus. They do not show whether a person is currently infected. This is primarily a good way to track the spread of the coronavirus through a population.
In general, these tests aren’t reliable enough for individuals to act based on the results. And researchers say, even if you were certain you had antibodies to the coronavirus, it’s still unknown if that protects you from getting sick again. Still, these tests can provide good information about rates of infection in a community, where errors in an individual result have less impact.
What it does: This test identifies people who are currently infected with the coronavirus. It may be used as a quick test to detect active infections. Initially it will not be used to diagnose disease, but it may be used to screen people to identify those who need a more definitive test.” (C)
“Should I get an antibody test right now?
I would recommend it, but only if you’re part of a research study where your results are contributing to an understanding of what results actually mean. Otherwise, it’s generally not advisable to get tests unless we know what to do with the results, and we don’t yet. We don’t even know if most of the tests that have come on the market are accurate. There are now more than 150 tests, most of which have not been approved by the Food and Drug Administration.
Why does FDA approval matter?
The FDA is maybe best known for its role in helping make sure that drugs are safe and effective before they go to market. But the FDA does the same for tests, too. That includes nasal-swab tests to detect the coronavirus during an infection, and blood tests to detect antibodies after an infection. The approval process slows down the availability of tests, but the idea is that patients and doctors should have some assurance that the tests they’re using are at least somewhat accurate. Even the coronavirus antibody tests that are “approved” right now by the FDA are only being used under a special “emergency use authorization,” for which standards are looser than usual. The others could be total scams. You can sell almost anything and call it a coronavirus antibody test right now; the market is operating mostly on an honor system.
What makes one antibody test better than another?
The two key features are sensitivity and specificity. A test has to be sensitive enough not to miss the antibodies if they’re actually present, but specific enough not to accidentally show a positive result…
Why are we putting so much emphasis on antibody testing if the results don’t necessarily mean I’m superhuman?
Right now, the antibody tests are being used to help map out where the coronavirus has spread, like tracking the footprints it has left. Combined with other types of research, this information will eventually help identify who is most susceptible to infection, and why. Even if we can’t tell individuals that they are totally protected, we could theoretically begin to allocate scarce resources away from a city where 50 percent of people have antibodies to one where only 5 percent of people do.” (D)
“The World Health Organization has pushed back against the theory that individuals can only catch the coronavirus once, as well as proposals for reopening society that are based on this supposed immunity.
In a scientific brief dated Friday, the United Nations agency said the idea that one-time infection can lead to immunity remains unproven and is thus unreliable as a foundation for the next phase of the world’s response to the pandemic.
“Some governments have suggested that the detection of antibodies to the SARS-CoV-2, the virus that causes COVID-19, could serve as the basis for an ‘immunity passport’ or ‘risk-free certificate’ that would enable individuals to travel or to return to work assuming that they are protected against re-infection,” the WHO wrote. “There is currently no evidence that people who have recovered from COVID-19 and have antibodies are protected from a second infection.”
The statement comes days after Chile announced it would begin issuing immunity cards that effectively act as passports, allowing travelers to clear security at airports with a document that purportedly shows they have recovered from the virus. Authorities and researchers in other countries — such as France and the United Kingdom — have expressed interest in similar ideas, while some officials in the U.S., such as Los Angeles Mayor Eric Garcetti, have mentioned it as one possible facet of a reopening strategy.
The concept for such a card is largely based on the premise that an individual can only contract the coronavirus once before developing the necessary antibodies to fight it off. That premise undergirds another common theory: the concept, known as herd immunity, that if enough people have been infected with the coronavirus — and are therefore immune — its transmission will slow and the risks of infection will diminish even for those who haven’t caught it yet.
But these ideas depend to a large degree on the supposition that one cannot catch the coronavirus a second time — an idea that world health authorities said leaders should not count on right now. As of Friday, the WHO said, “No study has evaluated whether the presence of antibodies to SARS-CoV-2 confers immunity to subsequent infection by this virus in humans.”
What’s more, data reported from the world’s early COVID-19 hot spots, such as South Korea and China, have shown that a growing number of recovered patients appear to have suffered a relapse of the disease…
“People who assume that they are immune to a second infection because they have received a positive test result may ignore public health advice. The use of such certificates may therefore increase the risks of continued transmission.”” (E)
“Zehnder, who helped coordinate Stanford’s antibody test development, said it’s reasonable to assume the antibodies provide some level of protection, since most other viruses generally confer immunity after exposure. But out of an abundance of caution, we cannot say for sure if these antibodies grant immunity to COVID-19.
“It’s important to not make assumptions of being protected before you actually know because that could lead to dangerous behavior and spreading of a disease,” Zehnder said….
The main use of antibodies tests, at least now, is to help researchers understand the prevalence of COVID-19. We’re quickly learning that many people who were symptom-free, or even tested negative for COVID-19 on a diagnostic test, actually had the infection.
With that information, we can get a clearer read on how infectious the coronavirus is.
“If there are enough tests, it would be important to expand the testing to everyone so we understand the extent of viral spread in populations in the future,” Iwasaki said.
Antibody tests alone can’t open up the economy, but used alongside diagnostic tests, contact tracing, distancing and quarantining, these measures can help health officials get a better handle on the coronavirus. If we want to open up the economy, we need to know exactly what is going on with the infection, Zehnder said.” (F)
“The fact that most antibody tests can’t detect neutralizing antibodies is also relevant because some politicians are pushing the idea that these tests be used to clear those with past COVID-19 infections to interact with others again, a so-called immunity passport. Researchers are trying to determine whether the antibodies detected by current kits can act as a proxy for protective immunity, says Smith.
Another complicating factor for immunity passports is that antibody tests can’t rule out that a person is no longer infectious, says Smith. A study published in Nature this month found that viral RNA declines slowly after antibodies are detected in the blood. The presence of viral RNA could mean that the person is still shedding infectious virus.
Despite the challenges, once reliable antibody tests are available, they could be important to understanding which groups of people have been infected how to stop further spread, says Collignon. They could even be used to diagnose active infections when PCR tests fail, adds Smith.” (G)
“A new type of coronavirus test expected to offer clarity on how and when to reopen the nation has instead sowed confusion.
A blood test that can detect whether a person’s had the virus has been heralded as an important tool for policymakers. Not only would it help answer critical questions such as how widespread it is, the test would inform them when people can safety return to work or school and not worry about becoming ill.
But hopes for quick answers have been dashed as a lack of evidence raises questions about the accuracy and reliability of a wide swath of antibody tests now being marketed to hospitals, doctors and consumers.
Public health experts are questioning the precision of antibody tests now being deployed in communities nationwide. And they warn elected officials, business leaders and consumers should be careful about making decisions based on test results.
Colin West is a Mayo Clinic internal medicine doctor and professor who has tracked the accuracy of COVID-19 tests.
“We need to stop pretending the tests are perfect,” West said. A person who gets tested should not “suddenly stop wearing a mask or stop washing their hands. Or stop physically distancing.”
The problem, West said, is tests don’t have evidence to prove they are good enough to ease policies on social distancing.
“Hopefully we will get there at some point,” he said. “Right now, it feels premature.” (H)
“Experts said the FDA likely felt pressure to quickly allow antibody testing after it took several weeks to authorize commercial labs to perform diagnostic tests during the early weeks of the pandemic…
Because shortages made diagnostic testing hard to get during the early months of the pandemic, many are seeking antibody tests to answer whether they recovered from COVID-19…
Hospital systems such as Cedars-Sinai in Los Angeles are taking a different approach. It is working to validate commercial tests before offering to test to the public, said Dr. Rekha Murthy, an infectious disease specialist and associate chief medical officer.
“We need to allow science to drive our decision-making,” Murthy said…
Baird said such inaccurate testing could misinform decision-makers about critical things like fatality rates of COVID-19. More “false positive” tests could dramatically skew results, Baird said.
“It may cause you to erroneously believe that the fatality rates was much lower because you had many cases but few people died,” said Baird, acting chair and professor at the University of Washington Department of Laboratory Medicine.
West said questions about antibody testing accuracy are not meant to undermine the usefulness of the tests. The key is to balance the speed of testing while ensuring the accuracy science demands to produce useful results.
“We are dealing with a pandemic that demands rapid action,” West said, “but developing a robust evidence base with rigorous methodology is not a rapid process.” (I)
“Meanwhile, a flood of new test kits with varying rates of accuracy is now hitting the market. In the U.K., for example, Prime Minister Boris Johnson touted finger-prick antibody tests as a “game changer,” only for the government to realize that the 3.5 million tests it bought from China were not reliable enough to use. Of particular concern here is the false-positive rate: If the prevalence of COVID-19 is quite low in the population—say, 5 percent—and a test can identify people who are truly negative with 95 percent reliability, half of the “positives” it returns will be false positives. In other words, half of the people the test says have antibodies wouldn’t actually have them. “I wouldn’t want to tell a nurse or physician ‘Go back to work’ based on that,” Michael Osterholm, the director of the Center for Infectious Disease Research and Policy at the University of Minnesota, told me.
Moreover, Osterholm said, antibody tests don’t give a snapshot of the present. It can take two weeks for a patient to develop a detectable amount of antibodies in their blood, so antibody surveys are necessarily backward-looking. But when public-health officials are deciding whether schools or businesses are safe to reopen, the key piece of information is the number of people currently infected. “I want to know what is happening now,” Osterholm said, “and antibody testing will not get that to you.”
The key strategies for stopping the disease are still the same ones experts have been promoting from the beginning: testing, contact tracing, isolating for those who test positive for COVID-19, and social distancing for everyone else. “There’s going to have to be some level of new normal for a while,” Dean said. Ongoing antibody surveys will help clarify the true scope of the pandemic and the true proportion of asymptomatic carriers, and those data can indeed help inform public-health decisions. But as far as antibody testing goes, Gronvall said, “it’s not the silver bullet for everything.” “(J)
To relieve the stress, he runs daily. But what he really wants, like so many sports fans, is just to go to a baseball game.
“I don’t think there’s any place that I relax more than sitting in Nats Park and watching my now world champion Nats play a game,” Fauci, 79, who grew up in Brooklyn rooting for the Yankees and is now a Washington Nationals fan, said in an interview this week.
That will have to wait. The level of testing for the virus is not adequate enough to allow for such mass gatherings.’ (K)
- A.Coronavirus antibody tests have ‘really terrible’ accuracy, researcher says, by Elizabeth Cohen, https://www.cnn.com/2020/04/28/health/coronavirus-antibody-tests-terrible/index.html
- B.Antibody Test, Seen as Key to Reopening Country, Does Not Yet Deliver, by Steve Eder, Megan Twohey and Apoorva Mandavilli, https://www.nytimes.com/2020/04/19/us/coronavirus-antibody-tests.html?referringSource=articleShare
- C.How Reliable Are COVID-19 Tests? Depends Which One You Mean, by RICHARD HARRIS, https://www.npr.org/sections/health-shots/2020/05/01/847368012/how-reliable-are-covid-19-tests-depends-which-one-you-mean
- D.Should You Get an Antibody Test?, by JAMES HAMBLIN, https://www.theatlantic.com/health/archive/2020/05/coronavirus-antibody-test-immunity/611005/
- E.’No Evidence’ Yet That Recovered COVID-19 Patients Are Immune, WHO Says, by COLIN DWYER, https://www.npr.org/sections/coronavirus-live-updates/2020/04/25/844939777/no-evidence-that-recovered-covid-19-patients-are-immune-who-says
- F.Coronavirus Antibody Test: What Is It And What Does It Reveal?, Experts share what you need to know about the blood tests that show a COVID-19 infection and possible immunity, by Julia Ries, https://www.huffpost.com/entry/coronavirus-antibody-test-what-is-_l_5ea09110c5b6a486d08351a4
- G.Will antibody tests for the coronavirus really change everything?, by Smriti Mallapaty, https://www.nature.com/articles/d41586-020-01115-z
- H.Antibody tests were supposed to help guide US reopening plans. They’ve brought more confusion than clarity amid coronavirus., by Ken Alltucker, https://www.msn.com/en-us/news/us/antibody-tests-were-supposed-to-help-guide-us-reopening-plans-they-ve-brought-more-confusion-than-clarity-amid-coronavirus/ar-BB13s2EA
- I.Antibody tests were supposed to help guide reopening plans. They’ve brought more confusion than clarity, by Ken Alltucker, https://www.usatoday.com/story/news/health/2020/04/30/coronavirus-antibody-tests-immunity-mayo-clinic-who/3038740001/
- J.The False Hope of Antibody Tests, by SARAH ZHANG, https://www.theatlantic.com/science/archive/2020/04/antibody-tests-herd-immunity/610762/
- K.Fauci, Leading Fight Against Coronavirus, Misses Baseball, Too, by James Wagner, https://www.nytimes.com/2020/05/01/sports/baseball/coronavirus-fauci-baseball-running.html?referringSource=articleShare