WHO Opinion and PCR Test
Back in early March 2020, the head of the World Health Organization, Tedros Gebreisus, urged countries to conduct mass testing of a new type of coronavirus infection – even in people without symptoms. Moreover, according to WHO guidelines, SARS-CoV-2 coronavirus assays should be performed by reverse transcription polymerase chain reaction (PCR).
The document states that so far this is the most accurate and reliable diagnostic method, which allows even a small amount of SARS-CoV-2 RNA to be detected in human blood.
The first tests for coronavirus by PCR were developed at Charite in Berlin in January 2020 using real-time reverse transcription polymerase chain reaction (rRT-PCR). It was these tests that became the main for the millions of tests that WHO distributed to search for patients with coronavirus infection.
A similar method for searching for coronavirus is used by the South Korean company Kogenebiotech, which in its PCR tests allows you to find the E gene, common for all beta coronaviruses, and the RdRp gene specific for SARS-CoV-2.
In the United States, the Centers for Disease Control and Prevention distributes the RT-PCR diagnostic panel to public health laboratories through the International Reagent Resource. One of the three genetic tests in the older versions of the test kits yielded inconclusive results; many experts attribute the current development of the US pandemic to the fact that the initial tests did a poor job of finding the RNA of the virus in human blood.
Only on March 13, 2020, the American company Roche Diagnostics received FDA approval for a test that can be performed within 3.5 hours, which allowed one machine to perform approximately 4,128 tests in 24 hours and dramatically increase the number of tests for coronavirus in the USA.
Number of coronavirus tests performed by country
- USA – 8.3 million tests, or 25 thousand tests per 1 million population
- Russia – 4.98 million tests, or 34.1 thousand tests per 1 million population
- Germany – 2.7 million tests, or 32.8 thousand tests per 1 million people
- Italy – 2.3 million tests, or 39.3 thousand tests per 1 million population
- Spain – 1.9 million tests, or 41 thousand tests per 1 million population
- Great Britain – 1.53 million tests, or 22 thousand tests per 1 million people
- India – 1.4 million tests, or 1 thousand tests per 1 million population
- France – 1.3 million tests, or 21 thousand tests per 1 million people.
How does a PCR test work?
To conduct tests from physiological fluids of a patient — in the case of coronavirus, this is a swab from the oropharynx or nasopharynx — single-stranded RNA is extracted, double-stranded DNA is modeled on its basis, and it is repeatedly duplicated using a special enzyme (polymerase). Increasing the number of DNA copies is called amplification. As a result, the concentration of certain DNA / RNA fragments in a biological sample, initially minimal, increases significantly.
In Russia, almost all tests that are done in the 15 largest diagnostic laboratories in the country, including paid ones, such as Helix, are performed by the Vector Center for Virology and Biotechnology, Novosibirsk.
EMG Tests
March 20, Roszdravnadzor gave permission to use the Russian-Japanese diagnostic system for the detection of coronavirus, which was brought to the Russian market by Evotech-Mirai Genomix (EMG). Russian-Japanese technology for express diagnostics COVID-19 is a joint development of the Japanese company Mirai Genomics and its Russian partner Genetic Technologies, which is a test and portable diagnostic system.
The technology allows for high-precision express diagnostics of the virus in 30 minutes. Due to the fact that the technology is adapted for mobile laboratories, it allows you to test people anywhere and can process samples of 20 people at once.
Now this system is most often used by Yandex to conduct its own testing for coronavirus in Moscow. The tests themselves, like many reagents, are made in Russia. It is planned that the price for EMG tests will be on average five times lower than for standard PCR tests in Europe.
The key difference between EMG tests and PCR is that they perform ELISA (enzyme-linked immunosorbent assay). This technology determines the antibodies that the body begins to produce no earlier than a week after infection – the so-called early antibodies, later ones are replaced. At the same time, the EMG test allows you to determine the presence of the virus already at the very early stages, while other coronovirus diagnostic systems are less sensitive and cannot detect the virus at an early stage of infection.
Antibody test
A test for antibodies to coronavirus allows you to find out whether a person has had COVID-19 and has special proteins in his body that fought this virus and can hypothetically resist it in the future. We have described in more detail about this analysis here.
Antibodies to coronavirus can also be tested in Russia, but mass testing is carried out only for doctors using the Novosibirsk test system “Vector”. Also on a small scale, the Israeli clinic “Hadassah Medical” in Skolkovo is engaged in such studies.
At the end of April it became It is known that five large networks of medical laboratories will immediately begin mass testing of Russians for antibodies to coronavirus: Helix, INVITRO, Gemotest, KDL and LabQuest. They plan to detect antibodies: early – IgM and late – IgG, which replace the early ones with a primary immune response to an antigen unknown to the body.
However, while on the sites of these clinics are invited to take a test for coronavirus. In the future, their price will be from 900 to 4,000 rubles, depending on the region.
New Coronavirus Tests
At least 10 experimental testing systems for COVID-19 are currently being developed in Russia, and at least several hundred worldwide. For example, the FDA recently approved first coronavirus test using CRISPR technology. Its results become known within an hour.
Company Northwestern recently released a patch-like sensor that can diagnose potential early-stage coronavirus infection of a new type.
At the same time, it is practically pointless to take a PCR analysis without symptoms, since the virus is looked for in the epithelial cells from the nasopharynx, and the absence of symptoms means that it has not yet affected the nasal and throat mucosa. At the same time, the virus can be in the cells and simply do not reach the mucosa. Therefore, with a negative analysis, the test is usually sent for verification and repeated.
Read also:
NASA showed the most detailed image of ancient rivers on Mars
Astronomers have found a black hole closest to Earth
Chinese scientists have created liquid metal, as in the movie “Terminator 2”
–
