Evaluation of the flu rapid test

After a waiting period of 10 to 15 minutes, the flu rapid test can be evaluated. The positive result appears as a color change in the form of a purple or pink line. If the result is negative, this line is missing or no color change is visible. There is a control line for comparison. The display reminds of a pregnancy test.

How reliable is the flu rapid test?

When performed correctly, the rapid tests provide a fairly reliable result. The gold standard for the detection of influenza viruses is the laboratory test in which the genetic material of the viruses is represented. It has a reliability of up to 98%.

The rapid influenza tests provide a correct result to 80-85%. Since influenza viruses can only be detected for 3 to 4 days, however, a smear taken too late can lead to a false negative result. Since the rapid influenza test only gives a correct result in 80-85% of cases, the probability of a false positive or false negative result is 15-20%. If the test is used at home by non-professionals, the risk of a false result increases due to potential application errors.

What can I not test with the flu rapid test?

If the infection is more than 4 days old, the rapid flu test cannot provide a reliable result. Furthermore, it can only detect influenza virus strains A and B. It is not possible to show which influenza pathogen is involved. The polymerase chain reaction, which detects the virus in laboratory tests, can on the other hand determine the exact virus, e.g. also swine flu or bird flu.

Swine flu
Bird flu

Can I buy the rapid test over the counter at the pharmacy?

You can buy the rapid test for influenza for about 15-18 € in the pharmacy. One package often contains several test sets. Usually no prescription is necessary, since it is a voluntary service.