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Breaking down the nuances: what coronavirus tests are available to Russians
27 April, 12:11
Breaking down the nuances: what coronavirus tests are available to Russians
Photo: diagnozlab.com
While some are in a hurry to get vaccinated against coronavirus, others have taken a wait-and-see attitude, and some are totally against the vaccination.

But one thing can be said for sure about both those and others: to find out whether immunity has developed, whether there are antibodies - after all, perhaps the disease was transferred asymptomatically - it is interesting and important for everyone.

Novye Izvestia decided to find out what types of SARS-CoV-2 / COVID-19 diagnostics are now available to Russians.

So, firstly, these are RNA tests, they report data on the current infection. Biomaterial: swab from the mucous membrane of the nasopharynx and / or oropharynx. There are tests from different manufacturers, for example, from Roche (EU) and Vector-Best (Russia). Test completion time: from 1 to 2 working days.

Such tests are informative as early as 7 days after infection or the appearance of the first symptoms of the disease. But it is worth remembering that this period is, of course, approximate - due to the variability of values in different studies and individual characteristics of a person.

Secondly, on April 5, a new study was launched in Russia - a quantitative test for determining the SARS-CoV-2 antigen in a swab from the nasopharynx and oropharynx . Test completion time: 1 business day.

The analysis for viral antigens allows you to detect the pathogen directly in the biological material of a person.

A positive result indicates the current infection and the degree of contagiousness (infectiousness). A negative result means that the SARS-CoV-2 antigen is absent or its concentration in the biomaterial is below the sensitivity limit of the method.

Let's not forget that the result of an antigen test, like the result of a PCR study, is relevant only at the time of the test and does not at all guarantee that a person could not become infected immediately after it was carried out.

However, it is important that in assessing the degree of infectiousness of a patient, a quantitative antigen test is still much more informative than a PCR study.

“Quantitative antigen tests are indeed more informative than PCR studies in assessing the degree of contagiousness (infectivity) of a patient. Research results have shown that in some cases, recently recovering from COVID-19 may have a positive PCR test result for some time. This is due to the fact that the results of highly sensitive PCR tests can detect fragments of viral RNA in low concentrations, which does not always indicate the infectiousness of the subject. Therefore, if a person has recently been ill with COVID-19, he may have a positive PCR test result and a negative antigen test result", - said Tatyana Pankratova, head of the medical marketing department of the Invitro group of companies.

Thirdly, high-quality tests for antibodies are available to Russians: IgM (a positive result indicates a current or recent infection; the deadline is 1 working day ); IgG to the nucleocapsid protein (a positive result indicates a previous infection; deadline 1 working day); and the test for IgG to the spike protein (to the RBD domain) can be either of high quality (up to 3 working days), or from now on! - and quantitative (deadline 1 working day).

A quantitative test for the determination of specific class G immunoglobulins has been available to Russians since April 3. It allows not only to establish the presence of an immune response to the SARS-CoV-2 virus, but also to assess the strength of immunity against COVID-19, tracking the dynamics of the level of antibodies in the blood over time.

A positive quantitative spike protein IgG test indicates a past infection and also indicates the degree of protection (strength of immunity) after vaccination against COVID-19.

Positive qualitative test for IgG spike protein suggests moved past infection or vaccination conducted by COVID-19.

By the way, in general, it is recommended to study the IgG index to the spike protein both before and after the Sputnik V vaccination. Biomaterial: venous blood.

“There are three main indications for a quantitative test for IgG antibodies to the SARS-CoV-2 spike (S) protein. First, this test is needed to clarify COVID-19 infection and its complications in addition to PCR tests. Secondly, the test is informative for assessing the presence and level of specific antibodies to SARS-CoV-2 after an illness. Thirdly, this test is necessary to monitor changes in the level of IgG antibodies after vaccination, which is very important for assessing the epidemiological situation”, - says Andrey Pozdnyakov, infectious disease doctor, chief physician of the clinical diagnostic laboratory of INVITRO-Siberia LLC.

By the way, in all Invitro offices such a test is performed within 2 working days, excluding the day of taking the biomaterial. In Moscow, the cost of this test is 1290 rubles, but the price may differ depending on the region of residence.

Fourthly, there is a high-quality rapid test for IgM + IgG. It will take only 15 minutes to complete.

Biomaterial: capillary blood. A positive test indicates a current or recent infection, or a past infection.

By the way, antibodies to SARS-CoV-2 have already been identified in 32.5% of people who were examined in that same Invitro, which means that the collective immunity to the infection is steadily growing. And, of course, this is good news.