Having symptoms compatible with those of Covid-19 but the negative buffer, which becomes positive when they have faded. More and more people report this “time lag” which has attracted the attention of the scientific community. To explain it is the federation of the Order of doctors, in the web column “Doctor, but is it true that?”. It is difficult to estimate how many cases it affects, and which people are most at risk, especially as fewer and fewer people undergo official tests. Just as it is difficult to understand the cause. Three hypotheses.
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The most supported hypothesis “is linked to the behavior of our immune system: it is thought that the symptoms precede the positive test result because today the immune system is activated much faster against the virus. At the beginning of the pandemic, in fact, infections occurred between people who did not had never taken Sars-CoV-2 before and were not vaccinated, and the virus could act undisturbed for several days before the infection was such that it was detected by the immune system. Today, however, with the majority of the population being vaccinated or already exposed to the virus, the immune reaction is faster and can lead to cases in which you have symptoms, but you are not positive, because the viral load is not yet sufficient compared to the sensitivity of the test “.
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Another hypothesis it concerns the different dynamics with which the most recent variants circulate in the organism. Some studies, in fact, have found, with the new variants, a lower accumulation of viral particles in the cells of the nose, making false negatives more likely.
A third possibility is that it is a reflection of the increased use of do-it-yourself tampons, many people do not carefully collect the biological material, resulting in more false negatives. No need to worry for now, but it can be useful to take some precautions. “A negative test for symptoms shouldn’t be a pass to get out,” confirms Emily Martin, an epidemiologist at the University of Michigan. And this is true in the presence of all types of viruses.