Until now, antibody tests, unlike antigen tests, had to be performed in laboratories after a blood sample had been taken – including several days of waiting for the result. But Japanese experts have now developed a method in which antibodies against Sars-CoV-2 can be detected without taking any blood. This was reported this week by the German medical journal Ärzteblatt.
Measuring 1.5 by 3.5 centimeters, the patch test / Image: Institute of Industrial Science, The University of Tokyo
Experts developed the rapid test at the University of Tokyo. This novel test is extremely easy to use: You just stick a patch on your skin. The result should then be readable after just a few minutes.
Samples are taken using fine “needles” attached to the underside of the patch. These are crystals consisting of polylactides. These penetrate the skin when applied, and the tissue fluid is drawn into the cellulose layer of the patch.
Two and three “dashes”
Just as we know from the antigen tests, the result is shown with discoloring dashes. However, two different types of antibodies are detected. Three dashes will appear if you have had a Covid 19 infection within the last three weeks: one control dash, one for detecting IgG antibodies, and one for IgM antibodies. If the infection was longer ago, two dashes should appear, for IgG detection and the control dash. And there is another scenario – if the infection is still active or about a week ago, two lines should also appear, one for IgM antibodies and one for control. IgM antibodies are formed earlier in the course of infection than IgG antibodies.
It is important to emphasize that an antibody test cannot replace a rapid antigen test. Namely, “because the antibody reaction always starts only a few days after the infection,” as Ärzteblatt points out. But if the goal is to conduct a representative antibody or dark count study across large groups, this patch could undoubtedly facilitate the investigations.
- source: kleinezeitung.at/picture: pixabay.com
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