Karl Lauterbach, a public health expert at the Social Democrats, recently told German public broadcaster WDR that self-testing kits could help curb the pandemic. “If the general public takes regular tests – for example before visiting family or friends – we can quickly inflame chains of infection.” Lauterbach said self-test kits are “very reliable”, adding that they “may not be all cases, but almost all contagious” can not detect cases. “
Is Lauterbach’s claim accurate? And what do we need to know about self-test kits?
How do self-tests work?
Rapid self-tests can be administered individually and independently. These SARS-CoV-2 antigen tests can be performed anywhere and do not require any equipment. Results are available 15 to 30 minutes after the test. Some tests require a mouth or nose swab. Other, more recent test kits work with saliva or stool samples.
The Robert Koch Institute (RKI), the German public health authority, says test strips that contain antibodies bind antigens, which activate an enzyme. A positive result will yield a visible color. The RKI says antigen self-tests are particularly suitable for detecting high virus loads that are particularly contagious.
How reliable are self-test kits?
Approved rapid self-test kits should guarantee the sensitivity of more than 80%, which means that they should detect four out of five infections. Approved test kits must also ensure a specificity of more than 97%, which means that it can only yield three false positive results if performed on 100 individuals.
In reality, however, fast self-test kits are less reliable. In a RKI study among 60 individuals who tested positive for SARS-CoV-2 in a PCR test, the rapid antigen test was found to detect only 71.7%. This means that approximately every third infected person has a false negative. However, the study found that both test variants were equally capable of detecting non-infected individuals.
How easily are these tests administered?
Self-test kits currently available on the German market must be administered by trained personnel. The reason for this is that mistakes can be made while collecting samples. In addition, individuals may struggle to apply deep mouth or nose swabs to themselves.
A recent study, conducted in part by the Charité Hospital in Berlin, found that a layman could be trained to apply a rapid self-test properly. The study involved 146 individuals who showed symptoms, of which 40 tested positive for SARS-CoV-2 using a PCR test. All subjects then performed additional self-tests using nasal swabs. Of all those who tested positive, 91.4% were able to confirm their result through a quick self-test. And virtually everyone who tested negative was able to confirm their result with a self-test.
Who can buy self-test kits?
At present, self-test kits are only available to specially trained individuals, as it is unclear how reliable they can be administered by lay people. At a press conference last week, German Health Minister Jens Spahn said the danger of false negative individuals could lead to coronavirus safety measures. The ministry has announced that self-tests will be optimized for ease of use.
The German Institute for Medicines and Medical Aids (BfArM) told DW that 30 requests for special approval for self-tests for trained staff had been submitted. Maik Pommer, spokesperson for BfArM, said he expected the first kits to be temporarily granted in early March.
Will antigen self-tests stop the coronavirus pandemic?
We know that rapid tests account for only about 70% of SARS-CoV-2 infections. This means that these tests yield very false negatives, which can give individuals a false sense of security. And for now, these tests do not remain available to laymen.
Medical experts from the German Applied Surveillance and Testing Research Network have stated that negative test results should not be used as an excuse to ignore coronavirus safety rules. They emphasize that hygienic measures must be taken into account, especially with regard to the protection of individuals at risk.
Karl Lauterbach claims that although self-tests may not detect all SARS-CoV-2 cases, they do detect infections in particular. We find no evidence to substantiate such a general claim.
The Paul-Ehrlich Institute, which is responsible for vaccination in Germany, says that self-tests detect the most reliable infections when individuals show no or only weak symptoms. The RKI meanwhile writes that it remains unclear at what stage infected individuals are contagious. This means that there is a possibility that people who have been infected for a while may be contagious and still test negative using the antigen method.
Since fast antigen self-test kits are not yet available for home use, it is impossible to project how this will affect the pandemic. However, a well-thought-out campaign to conduct speed tests with trained staff can be effective.