When people who have recovered from CoV test negative again and the CT value is above 30, they are healthy again. But for some, it happens that the test is positive again after days or even weeks. The reason: fluctuating viral load after infection.
According to virologist Monika Redlberger-Fritz, the virus is excreted very slowly in those affected. For some, there are even weeks or months between tests. “It’s also called a ‘blip,’ where that can happen again, that this sample becomes positive again. That’s why all these screening tests also ask whether one was also positive in the last three months,” Redlberger-Fritz explained to “Wien Heute” on Saturday.
CT value as a jumping point
If the test is positive again, the further procedure depends on whether one develops symptoms or not. The CT value is vital in this context. In Austria and many other countries, a matter of 30 or more is considered to be no longer infectious. In the PCR test, genetic material taken from the mucosa is exponentially multiplied in the laboratory to determine whether the sample contains viral material. The CT value indicates the number of times the virus has been detected.
“Most don’t have any symptoms at such a stage and only notice it in and of itself through this testing. However, sometimes, exceptions develop symptoms again, and the CT value drops below 30. Then we would say again: The next few days again in quarantine until then the symptoms are gone again and above all the CT value also rises again above 30,” says the virologist.
Doctor decides on a case-by-case basis
The city’s health service says that a healthy, immunocompetent person can be assumed to be no longer at risk of infection after ten days. If one is positive again within three months after the infection, a case-by-case medical decision is necessary, it said.
But a suddenly positive PCR test again can also have another reason – free testing after five days of quarantine: “Many go free testing on day five, regardless of whether they have symptoms or not. And that is fundamentally wrong. Because it says in all the guidelines that you have to be symptom-free for at least 48 hours and then you can go free after five days at the earliest.”
Testing at the same time of day is advisable
Because the viral load still fluctuates when the disease subsides, it can increase again shortly after free testing. In general, virologists advise that PCR tests should always be carried out at the same time of day for optimal results.
- source: orf.at/picture: pixabay.com
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