Winter temperatures increase the risk of a false positive self-test, says Professor Herman Goossens. “Always store and do your self-test at room temperature,” he warns. That is what the Mediahuis newspapers write.
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Door Redactie Online
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Goossens was head of the Testing task force until September, and yet he was also surprised on Sunday when all those present at a Christmas party turned out to be ‘weak positive’ in a self-test. In other words, a hint of a line appeared.
«Celebrated Christmas with (grand) children yesterday. Windows open and everyone outside (8°C) tested before entering the house. Lack: everyone weak positive. Everyone retested at room temperature: all negative. Beware of false positive results in winter. Known issue,” he wrote on Twitter.
With ‘known problem’, the microbiologist refers to a study that he had himself carried out at the beginning of 2021. “It showed that self-tests at temperatures of 2 to 4 degrees Celsius gave false positive results,” he tells the Mediahuis newspapers. “But that that can be the case even at 8 degrees, I’m amazed, yes.”
Cause?
It is not clear what caused these incorrect results, says Goossens. «Perhaps there is a chemical reaction at temperatures that causes such a line on the self-test. That has nothing to do with the virus. But we’re still in the dark there.”
Goossens therefore advises everyone to only store and perform self-tests at room temperature. «Keep that test in your pharmacy cupboard. So not too hot either, because we know that the tests lose sensitivity at temperatures above 37 degrees.”
