The reason why many infected with the Omicron variant are negative in the tests
Photo: MICHAEL REYNOLDS / EFE
Ómicron continues to advance throughout the world Well, according to statistics from the World Health Organization (WHO) 70% of the new cases of Covid on the planet are due to this variant that on paper seems to be less dangerous but much more transmissible.
It is also known that Omicron can be easily confused with the flu because the symptoms are similar; This is why thousands of people are seeking a coronavirus test daily in order to rule out any contagion.
Given the need to know soon whether or not you are positive for Covid, people turn to antigen tests, especially since it yields fast results that are reliable, as well as being inexpensive. What these tests do is measure the viral load of SARS-CoV-2 (that is, the concentration of the virus in our body) and also reveal the stage where we are most contagious.
The problem is that It seems that with Omicron, some people who have become ill with Covid assure that the first tests of this type that were carried out were negative. and only days after having applied them again they obtained an accurate result.
Why can the Covid tests give a negative result if you were infected with Ómicron?
Health specialists explain that The best way to detect a respiratory infection is by extracting mucous samples from the nose; but nevertheless, in the case of Ómicron this is better detected in saliva.
This was found in a study of 30 people in the United States with which it was possible to demonstrate that rapid antigen tests performed with saliva samples had a viral load peak between one and 2 days earlier than when a nose swab is used.
Other research in South Africa found that while nasal swabs worked better than saliva swabs when trying to detect the delta variant with PCR tests, the opposite happened with Ómicron. This is possibly because this lineage replicates faster in upper respiratory tract tissue.
Another factor for which you could get an erroneous negative result in a Covid test, according to the American epidemiologist Michael Mina, Vaccines could also influence the issue of immunity and in the same way if you had previously been infected with coronavirus.
With Ómicron, the recognition of the coronavirus and the response against it happen in less time due to the acquired immunity. For that reason, symptoms can develop even before the viral load is sufficient to be detected with an antigen test.
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