PCR

Customers ask for a PCR by name, usually meaning they want the accurate one. The useful reply describes what the method does rather than agreeing that it is better.

A PCR looks for the genetic material of the pathogen itself. That is a direct finding, and it is why the method can detect an infection early, before the body has produced anything measurable in response. An antibody test does the opposite and looks for the body's answer, which takes time to appear. The two therefore answer different questions and have different windows, so neither is simply the better one. See diagnostische Lücke for what that window means in practice.

Two limits belong in the same sentence. A PCR proves that the material is present, not that the person is ill, and not that they are still infectious. And a PCR is only as good as the sample it starts from, so an Abstrich taken with too little contact produces a clean, confident and useless negative.

For a pharmacy the practical point is where the analysis happens. A PCR is laboratory work and goes to an akkreditiertes Labor, unlike a Point-of-Care-Test that gives an answer on the spot. That difference decides how long the team should say a result will take, and it decides who may state what the result means.

The handling rules that surround the method are the ones a pharmacy actually controls. Every PCR sample carries a transport medium and a stated window, both of which sit in the Präanalytik rather than in the analysis, and a sample that dries out or arrives late is not a weak result but no result at all.

One sentence covers the counter conversation. A PCR looks for the pathogen itself and an antibody test looks for the body's answer to it, so the right choice depends on when the sample is taken rather than on which test sounds better. If a customer insists on a PCR for a question a PCR cannot answer, the honest reply is to say which test answers it.