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The result of a rapid test is only valid within the time window specified in the instructions for use
Photo: Gingagi / iStockphoto / Getty Images
Many people are now used to using corona self-tests at home.
A stripe usually appears in the display window after just a few seconds, which provides relief: negative.
But of course you then have to wait a little longer to really be sure that no second line appears - at least 15 minutes in most tests.
But what if these are long gone and a second strip appears on the test cassette some time later?
Users should follow the manufacturer's specifications here.
The diagnostics industry association reports that the test result of a rapid antigen test for Sars-CoV-2 is only valid within the time window specified in the instructions for use.
Delayed positive result not valid
Between 15 and 30 minutes
could
this period of time may vary depending on the provider.
If another line develops next to the control strip during this time, the test is positive.
In such a case, the Federal Ministry of Health advises isolating yourself and having the result confirmed by a PCR test.
However, if the second strip on the self-test is delayed beyond this period of time, this is not a valid test result, according to the association of the diagnostics industry and advises for this scenario: do another test, if necessary with a quick test from another manufacturer.
more on the subject
New virus variant: How reliable are rapid tests for omicron infection?By Julia Merlot
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The association, of which many test providers are members, emphasizes: "A follow-up test with a PCR test is then only necessary if the rapid test result is valid and positive." In other words, if a positive result is visible within the specified reading window.
On the other hand, it makes no difference to the result whether the second stripe appears strong or rather pale: Because different factors can influence the severity of the stripe, no reliable conclusions can be drawn about the viral load, explains the industry association.
Even if only a faint streak shows up within the time window, one should react accordingly.
Not 100% security
With the rapid tests, it should also be borne in mind that they do not detect every corona infection. This conditional validity has been known for a long time. The Paul Ehrlich Institute (PEI) writes on its website that self-tests can only detect an infection if there is a high viral load at the time of the test. This also applies to the Omicron variant. A negative test result is therefore not one hundred percent certain that you are not infected with Sars-CoV-2. If those affected have no symptoms, the rapid tests are also often falsely negative – i.e. they show a negative result in the case of infected people.
In addition, the quality of the antigen tests varies greatly.
Not all reliably detect an infection, even in those infected with a high viral load.
The PEI regularly conducts random checks to determine how reliable which tests are.
In this way, users can find out how good their test is.
mar/dpa