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| Science & Technology |
| Coronavirus Antibody Tests: Can You Trust the Results? |
| 2020-04-25 |
| h/t Hot Air [NYT] - A team of scientists worked around the clock to evaluate 14 antibody tests. A few worked as advertised. Most did not. Surprise! Surprise! "act in haste, repent at leisure" They set up lines of laboratory volunteers: medical residents, postdoctoral students, even experienced veterans of science, each handling a specific task. They checked and rechecked their data, as if the world were depending on it. Because in some ways, it is. For the past few weeks, more than 50 scientists have been working diligently to do something that the Food and Drug Administration mostly has not: Verifying that 14 coronavirus antibody tests now on the market actually deliver accurate results. These tests are crucial to reopening the economy, but public health experts have raised urgent concerns about their quality. The new research, completed just days ago and posted online Friday, confirmed some of those fears: Of the 14 tests, only three delivered consistently reliable results. Even the best had some flaws. The research has not been peer-reviewed and is subject to revision. But the results are already raising difficult questions about the course of the epidemic. Surveys of residents in the Bay Area, Los Angeles and New York this week found that substantial percentages tested positive for antibodies to SARS-CoV-2, the official name of the new coronavirus. In New York City, the figure was said to be as high as 21 percent. Elsewhere, it was closer to 3 percent. Even 21% is not even close to "herd immunity" The idea that many residents in some parts of the country have already been exposed to the virus has wide implications. At the least, the finding could greatly complicate plans to reopen the economy. Already Americans are scrambling to take antibody tests to see if they might escape lockdowns. Public health experts are wondering if those with positive results might be allowed to return to work. But these tactics mean nothing if the test results can’t be trusted. In the new research, researchers found that only one of the tests never delivered a so-called false positive — that is, it never mistakenly signaled antibodies in people who did not have them. Two other tests did not deliver false-positive results 99 percent of the time. But the converse was not true. Even these three tests detected antibodies in infected people only 90 percent of the time, at best. The false-positive metric is particularly important. The result may lead people to believe themselves immune to the virus when they are not, and to put themselves in danger by abandoning social distancing and other protective measures. ...Other scientists were less sanguine than Dr. Marson. Four of the tests produced false-positive rates ranging from 11 percent to 16 percent; many of the rest hovered around 5 percent. There's a link in NYT that can be followed to the actual preprint. We don't know which particular tests were used in NYC and San Diego. But, 5% give 18% true positive in NYC and 0% true positive in San Diego (should've gotten at least 5% positive in San Diego) |
| Posted by:g(r)omgoru |
| #3 These numbers don't seem all that surprising. The better tests sound kind of encouraging. Nothing is 100%, and you have to factor in lab handling errors too. |
| Posted by: James 2020-04-25 21:56 |
| #2 Actually, NYC probably used Chines made tests. |
| Posted by: g(r)omgoru 2020-04-25 18:07 |
| #1 No, and do they matter? Who knows? |
| Posted by: Glenmore 2020-04-25 18:06 |