A new review released Wednesday shows an unfortunate picture of the status of antibody tests aimed at finding out if you’ve ever had covid-19. He suggests that these tests vary enormously in accuracy from one manufacturer to another, with tests that quickly yield such bad results in the doctor’s office that they probably shouldn’t be used at all for now.
Antibody or serological tests are designed to look for the specific antibodies that our bodies produce in response to coronavirus infection caused by covid-19. Wwhile these tests are not intended to diagnose an active infection, they ideally you should tell him if you have ever had the virus in the past, even if you did not feel sick at the time. It has actually been more complicated than that.
Covid-19 antibody tests first available in the United States around March and April, although some countries had developed their earlier versions But many of the tests initially released on the global market were licensed for use with little external validation of their accuracy by relevant health agencies in countries such as the US Eventually, the Food and Drug Administration tighter restrictions on the approval or approval of these tests. met now maintains a list of tests that have been withdrawn from the market, bHowever, the landscape of antibody testing still seems to be riddled with rags.
In this new review, published In tAt BMJ, the researchers analyzed 40 studies evaluating the accuracy of covid-19 antibody tests developed around the world. These studies attempted to measure the sensitivity (the higher the percentage, the less chance of a false negative) and the specificity (the higher the percentage, the less chance of a false positive) of these tests. They also grouped the results, grouping them by the types of tests studied. The studies were carried out in China, the USA, Italy and Japan, among others.
Overall, the studies themselves were not necessarily of high quality. Half had not gone through a peer review at that time, and almost all were considered high risk of bias in some way, both in patient selection chosen for the study and how the results were interpreted.
G / O Media may receive a commission
The risk of false negatives also varied widely between tests, with a pooled sensitivity ranging from 66% to over 97.8%. The risk of false positives was less worrisome, with a pooled specificity ranging from 96.6% to 99.7%. Of the types of tests studied, it was the rapid point-of-care tests that had the worst overall results.
In a scenario where 10% of people in a city had contracted For the coronavirus, the researchers estimated, these rapid tests would erroneously find 31 false positives out of every 1,000 people tested, along with 34 false negatives. This may not seem a lot at first, but when you consider that some countries hope to use these tests on a large scale as a way to declare people safe from the virus, through so-called “immunity passports” It can be added.
In fact, the authors wrote that their findings should “stop governments considering the use of serological tests, in particular point-of-care tests, to issue immunity ‘certificates’ or ‘passports’.”
There are other concerns about using antibody tests as a way to confirm immunity from the virus. Evidence is beginning to suggest, for example, that some types of antibodies may disappear from covid-19 survivors in a few months, especially if they were asymptomatic (that does not necessarily mean that they will disappear). I losecommunity, even if). But in the short term, the authors wroteyou, there is no justification for using these seriously faulty rapid tests. And overall, there must be a concerted effort to better validate the accuracy of antibody tests before they reach the public.
TThe authors conclude that although the number of The evidence available so early in the pandemic is impressive, we need to have higher standards on how and when those tests apply. “While the scientific community should be commended for the rate at which new serological tests have been developed, this review underscores the need for high-quality clinical studies to evaluate these tools,” they noted. writea.
.
