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Juan Lama
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In 731 persons seeking COVID-19 testing at a walk-up San Francisco community site in January 2022, simultaneous nasal rapid antigen testing (BinaxNOW(TM)) and RT-PCR testing was performed. There were 296 (40.5%) positive tests by RT-PCR; 98.5% of a random sample (N=67) were the omicron variant. Sensitivity of a single antigen test was 95.2% (95% CI 92-98%); 82.1% (95% CI 77-87%) and 65.2% (95% CI 60-71%) for Ct threshold of < 30, < 35 and no threshold, respectively. We also compared BinaxNOW(TM) to RT-PCR from oral cheek swabs to nasal swabs (N=75); oral cheek specimen was significantly less sensitive than nasal swab. A single BinaxNOW(TM) oral cheek rapid antigen test failed to detect 91% (20 of 22) of specimens that were BinaxNOW(TM) positive from the standard nasal sampling. In a separate direct comparison of BinaxNOW(TM) between specimens collected from nasal or throat (tonsillar) swab (N=115), sensitivity was 97.7% for nasal and 48.8% for throat swabs that were PCR-positive on nasal swab with a Ct threshold < 30. Among persons with either a nasal or throat RT-PCR positive swab with Ct<30, BinaxNOW(TM) sensitivity was 85.7% for nasal and 89.8% for nasal plus throat swabs. BinaxNOW continues to be a very useful diagnostic during the omicron surge; oral (throat or cheek swab) should not replace nasal swabs due to significantly reduced sensitivity compared to nasal. As currently recommended, repeat testing should be done for high-risk persons with an initial negative antigen test result. Preprint available in medRxiv (Jan. 19, 2022): https://doi.org/10.1101/2022.01.08.22268954
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Juan Lama
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A new study adds to evidence that common rapid tests may fail to detect some Omicron cases in the first days of infection. A small, new real-world study suggests that two widely used at-home antigen tests, the Abbott BinaxNOW and Quidel QuickVue, may fail to detect some Omicron infections even when people are carrying high levels of the coronavirus. The study, which has not yet been peer-reviewed, focused on 30 people infected with the virus at five workplaces that experienced what were most likely outbreaks of the Omicron variant in December. The people received both saliva-based P.C.R. tests and rapid antigen tests using nasal swabs. It took three days, on average, for people to test positive on a rapid antigen test after their first positive P.C.R. result. In four cases, people transmitted the virus to others while the rapid test showed the negative result, according to the study, which was conducted by several members of the Covid-19 Sports and Society Working Group. It is not clear whether the infections were missed because the antigen tests are inherently less sensitive to Omicron or because saliva tests may be better at detecting the new variant. But the results are consistent with other preliminary evidence that the at-home tests that many Americans have come to rely on — at least as currently administered, with a nasal swab — may fail to detect some Omicron cases in the first days of infection. The researchers said they shared their results with federal officials — including at the White House, the Food and Drug Administration and the Centers for Disease Control and Prevention — in real-time, as the outbreaks were occurring last month. “They’re aware that there are flaws with antigen testing,” said Dr. Robby Sikka, an author of the study and chair of the working group. The study comes a week after the Food and Drug Administration released its own update on the effectiveness of the rapid antigen tests. “Early data suggests that antigen tests do detect the Omicron variant but may have reduced sensitivity,” the agency said. Many of the studies are early and small, and much more data is needed. The tests, which can deliver results at home in minutes, remain an important public health tool, and positive results are especially likely to be informative, many scientists said. (The wait for P.C.R. results can stretch for days.) “The message is not that we should stop using these tests,” said Isabella Eckerle, a clinical virologist at the University of Geneva in Switzerland. But people should be cautious about interpreting negative results, especially when they have symptoms or believe they may have been exposed to the virus. “It’s not a ticket that allows you to go back to normal or to drop any other measures,” Dr. Eckerle said. Antigen tests are designed to detect proteins on the surface of the coronavirus. If mutations in the virus change the structure of these proteins, antigen tests might fail to detect the variant. The Omicron variant has about 50 mutations, including more than 30 on the spike protein alone. Most rapid antigen tests are designed to detect more stable targets, which are far less mutated in Omicron. Still, even minor-seeming mutations can affect a virus’s surface proteins, “sometimes in non-obvious ways,” said John Moore, a virologist at Weill Cornell Medicine. “Only experimental data can determine whether there is an impact or not.” The F.D.A. in September told makers of rapid tests that they would be required to continue to test their products as new variants emerged, and, if asked, to share those results with the agency. Many companies have announced that their tests can detect Omicron, and several independent scientists said that they believed the tests should be capable of recognizing the variant, especially when present at high levels. But a few new studies raise questions about the tests’ sensitivity. The F.D.A.’s update stemmed from an evaluation it is doing with the National Institutes of Health, said Bruce Tromberg, director of the National Institute of Biomedical Imaging and Bioengineering. The scientists evaluated the antigen tests using pooled samples of nasal mucus collected from multiple people with Omicron, as well as similar pooled samples from Delta patients. Scientists then diluted each of these pooled samples until the antigen tests no longer detected the virus. The tests were able to detect more dilute solutions of Delta samples than Omicron samples, suggesting that the tests may be less sensitive to the new variant, Dr. Tromberg said. Still, he added, in real-world settings, “it may not translate into any different sensitivity.” An F.D.A. spokeswoman, Stephanie Caccomo, said last week that studies were underway “to confirm the reason for the apparent decreased sensitivity.” “Once that is known,” she said, “adjustments to existing tests can be undertaken by each developer with support from the F.D.A., if appropriate.” The F.D.A. update was not the first hint that some antigen tests may be less sensitive to Omicron. Dr. Eckerle and her colleagues recently evaluated the performance of seven antigen tests against samples of the virus grown from specimens taken from people infected with Omicron. Overall, the researchers found, the tests were less sensitive to Omicron than to previous variants. “They missed samples with infectious virus, and they missed samples that had quite a decent viral load,” Dr. Eckerle said. The work has not yet been published in a scientific journal. But there was also vast variability in the performance of the different tests, most of which are not available in the United States. And an Australian study, which examined a mostly different collection of antigen tests, found that the tests had a similar sensitivity to Omicron and Delta. More data are needed, experts said. “Each test is going to have to be evaluated independently any time there’s a new variant,” said David O’Connor, a virologist at the University of Wisconsin, Madison who urged people not to stop using rapid tests. “And that takes some time.” The new study focused on five New York and California workplaces that had virus outbreaks in December. In 29 of 30 people, samples of the virus produced a telltale genetic pattern on P.C.R. tests, suggesting that these individuals were most likely infected with Omicron. Each participant took P.C.R. and antigen tests daily over a period of up to 10 days. The discordant results overwhelmingly came during the first three days of infection. “A negative result may not actually be a negative result,” said Anne Wyllie, a microbiologist at the Yale School of Public Health and an author of the new study. “People should not ignore high risk exposures. They should not ignore symptoms.” The study’s other authors are Blythe Adamson, the founder of Infectious Economics, a public health consulting company, and Dr. Prem Premsrirut, the chief executive of Mirimus Laboratories, which offers saliva-based P.C.R. testing. An Abbott spokesman, John Koval, said on Wednesday that the finding that a P.C.R. test is more sensitive is “not new.” “Due to immediate turnaround time, frequent rapid antigen testing does slow transmission — and with a highly infectious variant frequent testing is needed, which is not realistic with P.C.R.,” he wrote in an email. Quidel’s president, Douglas Bryant, said in a statement that the company performed recent testing using samples from South Africa and confirmed that its rapid tests are detecting the Omicron variant. A company spokesperson also said that it was not surprising that saliva-based P.C.R. tests detected the virus before nasal swabs did, if the study accurately concluded that viral load peaks first in saliva. The company noted that its rapid tests only have F.D.A. clearance to collect nasal swab specimens. In a smaller analysis, of five participants who took both nasal and saliva-based P.C.R. tests, the researchers found that the levels of virus peaked in saliva samples a day or two before they peaked in samples collected from the nose. Those findings are consistent with a recent report from South Africa, which has not yet been reviewed by experts. The researchers found that P.C.R. tests picked up a higher share of Omicron infections when saliva samples — produced by the rubbing of a swab inside the cheeks, around the gums and tongue — were used instead of nasal samples. The reverse was true for Delta. “Ideally, until we can directly compare the relative sensitivity of the antigen tests, my suggestion would be to test both sites,” Diana Hardie, a clinical virologist at the University of Cape Town, who led the research, said in an email. One possible explanation for the findings is that Omicron replicates faster or earlier in the throat and mouth than in the nose. “While we’ll have to wait to see if the science bears out, that might be an indicator that that’s where the virus is growing first,” said Gigi Gronvall, an immunologist and testing expert at Johns Hopkins Bloomberg School of Public Health. “So if you’re going to look for the virus, which is what the tests do, then you may find more of it faster in the throat swab over the nose.” Anecdotal reports have also emerged that some people who tested negative on antigen tests when they swabbed inside their noses received a positive result when they instead swabbed the back of their throats. “There’s a lot of chatter around this,” said Nathan Grubaugh, a virologist at the Yale School of Public Health. “Obviously, that warrants further investigation.” Some tests available in Britain call for swabbing both the nose and the throat, but the antigen tests available in the United States are not authorized for the collection of saliva or samples from the throat. Omicron’s rapid replication also means that there is a narrower window to catch the virus before it begins spreading, and that people may need to test themselves sooner after a potential exposure and as close as possible to an upcoming gathering or event, experts said. They may also need to test themselves more frequently overall, a particular challenge when the tests are in short supply. People who may have been exposed to the virus should take at least two antigen tests over the course of about two days, experts said.
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Juan Lama
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Abbott Laboratories won Food and Drug Administration emergency clearance for its portable test for Covid-19 that will sell for just $5 and allow for “frequent mass testing” in schools and workplaces, the company said. The FDA’s “emergency use authorization” awarded to Abbott’s “BinaxNOW Covid-19 Ag Card” rapid test could be a game-changer given it turns around results within 15 minutes and could be administered in schools, workplaces and other sites. Such a test, which still requires a nasal swab by a health professional, is akin to a pregnancy test in its use of “lateral flow technology” and is about the size of a credit card. “With no equipment required, the device will be an important tool to manage risk by quickly identifying infectious people so they don't spread the disease to others,” Abbott said in announcing the FDA’s emergency use authorization. It’s the latest diagnostic test for Covid-19 that Abbott has developed. The company in March received an FDA emergency use authorization for the Abbott ID NOW Covid-19 rapid molecular “point-of-care” diagnostic test that can be used in temporary screening locations, doctor’s office labs and nursing homes to detect the Coronavirus strain COVID-19 within a half hour. But BinaxNOW is different than IDNow in that it requires “no instrumentation,” Abbott said. And the new BinaxNow includes a companion mobile app Abbott will launch for iPhone and Android devices and make available at no charge called NAVICATM” that quickly displays test results. "The massive scale of this test and app will allow tens of millions of people to have access to rapid and reliable testing," Joseph Petrosino, professor and chairman or molecular virology and microbiology at the Baylor College of Medicine in Houston said in a statement provided by Abbott. "With lab-based tests, you get excellent sensitivity but might have to wait days or longer to get the results. With a rapid antigen test, you get a result right away, getting infectious people off the streets and into quarantine so they don't spread the virus." Abbott said the new BinaxNOW tests will begin to be shipped by the end of the month with the company expecting to produce 50 million such tests a month by October. "We intentionally designed the BinaxNOW test and NAVICA app so we could offer a comprehensive testing solution to help Americans feel more confident about their health and lives," Abbott president and chief executive Robert Ford said. "BinaxNOW and the NAVICA app give us an affordable, easy-to-use, scalable test, and a digital health tool to help us have a bit more normalcy in our daily lives." FDA Letter of Emergency USE Approval (August 26, 2020): Abbott Press Release:
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Juan Lama
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Abbott on Friday announced it received approval for a test that is capable of delivering positive results of the coronavirus in as little as five minutes, and it will begin making those tests available to health care providers next week. The Food and Drug Administration issued emergency use authorization for the point-of-care test on Friday, the company said in a statement. The test can detect negative results in 13 minutes. The company said it plans to ramp up manufacturing so it can deliver 50,000 tests per day. “The COVID-19 pandemic will be fought on multiple fronts, and a portable molecular test that offers results in minutes adds to the broad range of diagnostic solutions needed to combat this virus,” Abbott Chief Operating Officer Robert Ford said in a statement. This is the second Abbott test for the coronavirus to be launched. Between the two, the company expects to produce about 5 million tests per month, the company said in a statement. The Lake Bluff, Illinois, company makes diagnostics, medical devices, nutritionals and medicines. A challenge might be that clinicians, due to the personal protective equipment shortage, might not feel safe administering these tests to patients, especially those with respiratory symptoms.
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Juan Lama
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The emergence of the SARS-CoV-2 Omicron variant has motivated a re-evaluation of the test characteristics for lateral flow immunochromatographic assays (LFIAs), commonly referred to as rapid antigen tests. To address this need, we evaluated the analytic sensitivity of one of the most widely used LFIAs in the US market, the Abbott BinaxNOW COVID-19 Ag At-Home Card using 32 samples of Omicron and 30 samples of the Delta variant. Samples were chosen to intentionally over-represent the range of viral loads where differences are most likely to appear. We found no changes in the analytic sensitivity of the BinaxNOW assay by variant even after controlling for variation in cycle threshold values in the two populations. Similar to prior studies, the sensitivity of the assay is highly dependent on the amount of virus present in the sample. While the analytic sensitivity of the BinaxNOW LFIA remains intact versus the Omicron variant, its clinical sensitivity is influenced by the interaction between viral replication, the dynamics of tissue tropism and the timing of sampling. Further research is necessary to optimally adapt current testing strategies to robustly detect early infection by the Omicron variant to prevent transmission. Preprint available in medRxiv (Jan. 11, 2022): https://doi.org/10.1101/2022.01.10.22269033
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Juan Lama
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In a small study in San Francisco, Abbott’s BinaxNOW identified infectious people nearly as accurately as a P.C.R. test. A $5 rapid test for the coronavirus may be nearly as effective as the slower, more complex polymerase chain reaction test for identifying people who may spread the coronavirus, a novel experiment has found. The study, conducted by scientists at the University of California, San Francisco, is among the first head-to-head comparisons of a rapid test and the P.C.R. diagnostic tool under real-world conditions. But the number of participants was comparatively small, and the data have not been peer-reviewed or published. A rapid test still cannot conclusively determine that an individual is not infected; the tests are intended primarily to detect the presence of high levels of the virus, rather than its absence, and are authorized only to evaluate symptomatic people. At the moment, anyone who has been exposed to the virus should be tested by P.C.R., said Joseph DeRisi, an infectious disease expert at U.C.S.F. and a co-leader of the project. At the moment, anyone who has been exposed to the virus should be tested by P.C.R., said Joseph DeRisi, an infectious disease expert at U.C.S.F. and a co-leader of the project. The new test, Abbott’s BinaxNOW, offers results in 15 minutes, compared with the days or weeks people may have to wait for a P.C.R. result. The Trump administration already has purchased 150 million BinaxNOW tests and plans to ship them to states for use in schools, nursing homes and meatpacking plants. The tests could also be used to screen people in communities where time, trust and resources are in short supply. The study assessed the BinaxNOW in one such community, a largely Latino neighborhood in San Francisco. On three mornings in late September, as commuters emerged from a BART train station in the Mission District, they were offered two nasal swabs: one for a P.C.R. test, the other for the rapid test with a simple readout. The commuters received only the P.C.R. result, by text, but the researchers compared both tests. Of the 878 people who took the tests at the train station, only 26 tested positive on the researchers’ P.C.R. BinaxNOW identified only 15 of them. But many experts have argued that the P.C.R. test is too sensitive, picking up fragments of the coronavirus lingering in the body long after people have recovered and are no longer infectious. A study by the company Becton Dickinson recently showed that rapid tests correlated better with live virus than P.C.R. But when they only considered P.C.R. results that corresponded to high viral loads, the researchers found that the BinaxNOW test detected 15 of the 16 people who were most likely to transmit the virus... Preprint available at medRxiv (October 5, 2020): https://doi.org/10.1101/2020.10.02.20205708
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Juan Lama
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The test, developed by Abbott Laboratories, usually still works properly, but initial guidance on how to administer it could have led to false results. Arapid test for the novel coronavirus that was unveiled by President Trump on the White House lawn and has already been used hundreds of thousands of times can falsely produce negative results in patients who are infected, according to clinicians and laboratory experts. The 13-minute test, developed by Abbott Laboratories, a major U.S. health care and medical device company, usually still works properly, the company and clinicians say. But Abbott’s initial guidance on how to administer the test — guidance approved by the Food and Drug Administration — could lead to an unspecified number of false negative results. Abbott says changing how samples are collected should fix the problem. The test “performed equivalent to the other platforms with patients that had high and moderate loads of virus,” said Alan Wells, a pathologist who directs the clinical laboratories at the University of Pittsburgh Medical Center. “However, with lower loads of virus, a large fraction of these patients were not detected as positive.” Wells ran a validation of the test compared with stored samples that had been tested on other platforms. In recent weeks, clinicians have expressed growing concerns about false negative results in testing for the coronavirus, known as SARS-CoV-2. Much of the problem has been blamed on issues with how samples for the main laboratory tests are collected. Since Abbott’s test, run on its “ID Now” platform, was granted emergency use authorization by the FDA on March 27, the company has shipped 600,000 tests. They are being used at CVS and Walgreens drive-through testing locations, to test nurses and police officers in Detroit, and at urgent care centers in Chicago. They are also being used in hospitals to test surgical candidates to determine if they should be operated on and what level of protective equipment physicians should wear. The test can be used in two different ways. In one method, a swab that has been rubbed against the nose, throat, or the area deep in the back of the nose is inserted directly into the ID Now platform, a toaster-sized machine. That approach is still seen as effective. But the FDA cleared the test to be used in another way: The swabs could be put in a liquid solution — known as “viral transport media” — and tested, which is the standard way for processing many other kinds of tests and usually allows samples to be stored longer....
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