Having recently been obliged to take a lateral flow test for Covid in order to fly from the UK, I idly wondered:

What is the control antigen for Covid lateral flow tests?

as (fortunately) that was the only band I saw.

Easy — just Google? You jest! “Other people asked”, “All you need to know” and even the scientific papers linked just talk about the target antigen.

This sort of thing really gets up my nose!

Could someone please tell me what it is up my nose?

  • $\begingroup$ You mean the red stripe at the upper control position of the test? See this question where it has been answered: biology.stackexchange.com/questions/101767/… $\endgroup$
    – Chris
    Jan 28, 2022 at 19:59
  • 1
    $\begingroup$ @Chris. I see. It is the test antibody itself. So this would seem to control only for addition of the test solution, and not whether I’ve swabbed my nose adequately. Is this correct? If so, it doesn’t seem correct. $\endgroup$
    – David
    Jan 28, 2022 at 20:09
  • $\begingroup$ @David, you are correct. Even if you don't swab the nose and put "clean" extraction buffer on the test card, you will get the "C" band. On my tests, even tap water gives the "C" band (although a bit lighter, but still clearly visible). $\endgroup$
    – Domen
    Jan 28, 2022 at 20:34
  • $\begingroup$ Absolutely correct. There is no control if you took the specimen correctly. Luckily most "corona skeptics" do not understand how this test works. As @Domen says, you get the control band with water only. Oh, btw. you can also fake a positive best by using a few drops of apple juice or coke. $\endgroup$
    – Chris
    Jan 28, 2022 at 21:25
  • $\begingroup$ @Domen Thanks. Well I’m waiting for a plane to take me to the ski slopes now. No point in going if I didn’t really test negative. First time in an airport for two years — never seen it so empty. Trust I can negotiate Swiss and French controls. $\endgroup$
    – David
    Jan 29, 2022 at 10:36


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