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Some German health officials say coronavirus self-test kits could go a long way toward containing the pandemic. DW looks into those claims.
Karl Lauterbach, a public health expert with the Social Democrats, recently told the German public broadcaster WDR that self-test kits could help to curb the pandemic. "If the general public regularly takes tests — for example before visiting relatives or friends — we could quickly disrupt infections chains," Lauterbach said. He called self-test kits "very reliable," saying they "may not detect all cases, but almost all contagious ones."
Is Lauterbach's claim accurate? And what should we know about self-test kits?
Rapid self-tests can be administered individually and independently. These SARS-CoV-2 antigen tests can be carried out anywhere and do not require any equipment. Results are available 15 to 30 minutes after taking the test. Some tests require an oral or nasal swab. Other, more recent test kits, work with saliva or stool samples.
The Robert Koch Institute (RKI), Germany's public health authority, says test strips containing antibodies bind antigens, which activates an enzyme. A positive result will produce a visible coloration. The RKI says antigen self-tests are particularly suited for detecting high viral loads that are especially contagious.
Approved rapid self-test kits must guarantee asensitivity of over 80%, meaning they must detect four out of five infections. Approved tests kits must also ensure a specificity of over 97%, meaning they may only produce three false positives when carried out on 100 individuals.
In reality, however, rapid self-test kits are less reliable. A RKI study among 60 individuals who tested positive for SARS-CoV-2 in a PCR test, found the rapid antigen test delivered a detection rate of only 71,7%. This means approximately every third infected individual got a false negative. The study, however, found that both test variants were equally capable of detecting non-infected individuals.
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 when collecting samples. Moreover, individuals may struggle to administer deep oral or nasal swabs on themselves.
A recent study, conducted in part by Berlin's Charité hospital, found that a layperson can be trained to properly administer a rapid self-test. The study involved 146 individuals showing symptoms of which 40 tested positive for SARS-CoV-2 using a PCR test. All subjects then conducted additional self-tests using nasal swabs. Of all those who tested positive, 91,4% were able to confirm their result via rapid self-test. And practically all of those who tested negative were able to confirm their result with a self-test.
Currently, self-test kits are only available to specifically trained individuals, as it remains unclear how reliably they can be administered by laypersons. At a press conference last week, German Health Minister Jens Spahn said the danger of false negatives could lead individuals to flout coronavirus safety measures. The ministry announced self-tests will be optimized for ease of use.
Germany'sInstitute for Drugs and Medical Devices (BfArM) told DW that 30 requests to grant special approval for self-tests for trained personnel have been submitted. BfArM spokesperson Maik Pommer said he expects the first kits to be given a temporary go-ahead in early March.
We know thatrapid tests only pick up on some 70% of SARS-CoV-2 infections. This means these tests produce many false negatives, which can give individuals a false sense of security. And for now, these tests remain unavailable for laypersons.
Medical experts with the German Applied Surveillance and Testing Research Network have stated that negative test results may not be used as an excuse to ignore coronavirus safety rules. They stress that hygiene measures must be heeded, especially regarding the protection of at-risk individuals.
Karl Lauterbach claimed that while self-tests may not detect all SARS-CoV-2 cases, they detect the particularly contagious ones. We find no evidence to substantiate such a general claim.
The Paul-Ehrlich Institute, which is charge of vaccination in Germany, says self-tests most reliably detect infections when individuals show either no or only weak symptoms. The RKI, meanwhile, writes that it remains unclear at what stage infected individuals are contagious. This means there is a possibility that persons who have been infected for a while may be contagious, yet test negative using the antigen method.
As rapid antigen self-test kits are not yet available for home use, it is impossible to project how they will affect the pandemic. A well thought out campaign to conduct rapid tests using trained staff, however, may be effective.