“I’m coughing, I’ve been stabbed in the lungs, my throat is scratching, I have a fever, I’ve been tested for a crown and I’m negative. How is that possible?” You can hear a story like this more and more often. Are the tests unreliable or is just not every cold a sign that you have Covid-19?
Epidemiologist Dr. Predrag Kon said that about 20 percent of Serbian citizens are infected with the corona and that there is no confirmation of this in any test. Many had mild symptoms, some had no symptoms at all, and a good portion of them had the virus on their feet.
– If 6,000 cases are confirmed in one day, it means that ten times more of them were infected that day, without even knowing it or having no confirmation that they are infected – Dr. Kon explained.
Infectious disease specialist prof. Dr. Dragan Delic.
– The existence of asymptomatic cases is generally good, because the one who passes the asymptomatic form, remains immune and learns that he was ill only when tested and is protected from the so-called. Body IgG against a specific virus. In that way, the collective immunity increases – Delic explains.
He says the virus is released two to three days before symptoms begin, while the day before symptoms appear, the virus is at its highest concentration.
– Then, for the next seven to ten days, the concentration of the virus in the secretion decreases, which means that one person pulls the virus for up to 12 or 13 days, which is a long period and a very unfavorable fact from the point of view of virus spread – concludes Delic.
However, Emina Milošević, assistant professor of immunology at the Medical Faculty in Belgrade, points out for Nova.rs that not all tests are equally reliable and that it is possible for someone to be infected with the corona, but not to be confirmed on the test. According to her, the PCR test is the gold standard for diagnosing coronavirus and there is no better method than this test.
– According to the guidelines of the World Health Organization, antigen tests are used only when the patient is expected to be positive, in patients with symptoms of the disease in the first five to seven days, as well as if the PCR test is not available – she states.
PCR, he explains, reveals the genetic material of the virus, while antigen tests reveal the proteins of the virus. PCR can detect a smaller amount of virus in a sample than an antigen test can do.
The sensitivity of all antigen tests is compared with PCR and it is recommended to use only those whose sensitivity is greater than 80 percent.
On the other hand, our well-known virologist Ana Gligić says that the corona virus mutates and that the symptoms in people infected with it change.
– The problem is mutations present in all viruses, but it turned out that coronaviruses have a specific, fast mutation, because we already have mutants in the strain that appeared and now we have an even more intense form of the virus – says Dr. Ana Gligić.
An antigen test is not a definitive confirmation
The use of antigen tests is not recommended in circumstances where the proportion of positive individuals is low, such as, for example, crossing the border or hospitalization of patients who do not have the disease,
– A negative antigen test can in no way be considered a final confirmation that the infection is not present, because it is possible that the antigen test is negative and PCR positive, which means that the virus is present – says Dr. Milosevic.
Virus reproduction rate – six people
What worries the corona virus, as stated by Dr. Delic, is the so-called reproduction rate, which is one to six in this virus.
– This means that one infected person can transmit the virus to six people. In the beginning, there was a story that it was about two, possibly three, and now the data show that it is up to six people – explains infectologist Delic.
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