Many cases have been reported of patients not testing positive until symptoms resolve. These are the possible reasons
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Many are asking the question during this new wave of covid: why do I have all the symptoms compatible with the coronavirus but the test is negative? In recent weeks, the idea has started to circulate that the tests no longer work correctly with the new variants in circulation, in particular with Omicron 5, which accounts for 75.5% of infections in Italy. Many of those who decide to repeat the test begin to test positive when the symptoms have already disappeared.
The reported “time lapse” caught the attention of the scientific community and the Italian College of Physicians wanted to analyze the problem in search of an explanation. It is not easy to estimate the extent of the phenomenon and the people most at risk because fewer and fewer people are turning to laboratory tests.
The behavior of our immune system
However, it is also difficult to understand the cause. The most widespread hypothesis is related to the behavior of our immune system: it is believed that the symptoms precede the positive result of the test because today the immune system is activated much faster against the virus. The appearance of the first symptoms would be a consequence of the activation of the immune system which fights the infection.
At the start of the pandemic, in fact, infections occurred among people who had never suffered from them before. coronaviruswho were not vaccinated, and the virus could act undisturbed for several days before the immune system could detect the infection.
Today however, with the majority of the population vaccinated or already exposed to the virus, the immune reaction is faster and can lead to cases where symptoms appear but are not positive, because the viral load is still not sufficient. with respect to sensitivity. of the test.
The dynamics of certain variants
Another hypothesis refers to the different dynamics with which the most recent variants circulate in the organism. Algunos estudios, de hecho, han encontrado una menor acumulación de particles virales de las nueva variants en las células de la nariz, lo que hace más probable los falsos negatives porque pendante la toma de muestras no se recoge la cantidad suficiente para dar positivo en la test.
Other studies have also found that micron it can, in some people, be detected in the mouth or throat before being in the nasal passages. Moreover, given the generic nature of the symptoms, it cannot be excluded that the manifestations are actually due to something else.
The execution of the test
A third possibility is that the delay reflects how the nasal swab is performed has changed over time. The greater use of home tests, in fact, can affect the quality of the result: many people do not collect the biological material in the nose with particular care or in depth, which leads to a higher frequency of false negatives.
Precautions even with negative test
There’s nothing to worry about right now, but it may be worth taking a few precautions. “If you start having symptoms, assume you’re contagious,” he explains. Yonatan Gradwho studies the coronavirus in the Harvard School of Public Health.
“People forget that as soon as symptoms develop, you have to behave differently. A negative test in the presence of symptoms should not be a pass to get out,” he confirms. Emily Martinepidemiologist expert in infectious diseases of the University of Michigan. And this is true in the presence of all kinds of viruses, not just the coronavirus.
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