Icon: enlarge
Saxony's Minister of Science Sebastian Gemkow with test strips for at home: antibody search in the blood
Photo: Sebastian Willnow / DPA
How does the test work?
Anyone who has been infected with Sars-CoV-2 usually forms antibodies against the virus.
These can be detected in the blood at the earliest one to two weeks after the onset of symptoms, so the test cannot detect an acute infection.
It is also still unclear how long the antibodies will be present after infection.
Anyone who orders the test or buys it in the pharmacy receives a collection set with which you can "quickly and easily" take a few drops of blood from your fingertip.
To do this, you prick your finger with a so-called lancet and drip the blood onto the enclosed filter card.
The sample must then be dried and sent to a laboratory in Leipzig, where the blood sample is examined for antibodies using the standard Elisa method.
Similar to the Corona-PCR tests for the detection of an acute infection, the result can be called up online within 24 to 48 hours.
Who developed the test?
The process called "AProof" is the result of a collaboration between the Biotechnological-Biomedical Center (BBZ) at the University of Leipzig and the company Adversis Pharma.
Who is the test for?
On the website, the manufacturers write vaguely: "Antibodies against Sars-CoV-2 can reduce the risk of illness in a critical work environment or with people at risk."
And: "With proven antibodies, a renewed infection is less likely."
The problem, however, is that far too little is known about what the detection of antibodies says at all.
It is unclear whether this alone proves a past infection or also protects against a second infection.
So far, the hope of many researchers has been that one is immune to the virus after infection.
But at the end of August, several cases of individuals became known who had become infected with Sars-CoV-2 a second time.
In addition, the body usually does not produce the long-term IgG antibodies for which the test is designed, which is easier to detect, a few weeks after infection.
So if you do the home test too early, you will not get a reliable test result.
But even those who do the test too late could get an inconclusive result.
Because there are also known cases in which the concentration of the antibodies decreases again after a while.
The following applies: For those with symptoms, a PCR test is the method of choice anyway, because it detects an active infection.
Antibody tests are more useful in asymptomatic patients who want to know whether they have already survived the infection.
How well does the test detect antibodies?
The company states that the test has a so-called sensitivity of 100 percent.
That means: Without exception, all users who have formed antibodies would be recognized by the test.
The specificity, i.e. the ability of the test to correctly identify those who do not have antibodies in their blood, is said to be 99.4 percent.
Does the lack of detection of antibodies mean that one was not infected?
Unfortunately, it is not that simple, as the observations in the former German Corona hotspot Bad Feilnbach show.
There, researchers were unable to detect any long-term IgG (immunoglobulin G) antibodies in 40 percent of the demonstrably infected.
What does the test bring then?
However, the process is not superfluous.
On the one hand, the user receives information about whether he has antibodies against Sars-CoV-2 or not.
If these are present, he was infected with corona.
Since the majority of those infected have only mild or no symptoms, the knowledge about an infection acquired afterwards could influence how the individual assesses the pandemic and deals with it.
On the other hand, the Leipzig scientists can use the data obtained to collect important information about the immune status, which in the long term could also play a role in epidemic surveillance and the development of vaccines.
Ralf Hoffmann, Head of Bioanalytics at the BBZ, pointed out that science was receiving valuable data on how many people in which regions had an infection.
What does the test cost?
When ordering online within Germany, the test costs 49 euros and is also to be sold in pharmacies.
Who paid for it?
According to the Saxony Media Service, the overall research project is planned to run until 2022 and will be supported with 323,000 euros from funds from the Free State and the European Union.
Icon: The mirror
hey
