[ad_1]
Countries use coronavirus screening tests to determine the number of infections and develop plans and measures to control their spread. But what are the available tests? Who should take the exam? Below is an attempt to answer the most important questions in this regard: What types of tests are available?
New screening tests are constantly appearing on the market. To date, there are more than 150 types of coronavirus screening tests. In general, these tests can be divided into two groups: the first group is diagnostic tests that reveal whether a person is infected with the virus at this time and whether they can transmit the infection to others, while the second group are tests that reveal if a person has been infected with the virus in the past and recovered from it.
Diagnostic tests
To diagnose a person’s infection with the virus, a test known as a “polymerase chain reaction” (PCR) is used, and tests called “isothermal DNA amplification,” which is very similar to “PCR, can also be used. ” In both cases, the swabs are taken from the saliva
After extracting a lumbar extract from a person’s upper respiratory tract, i.e. throat, nose, and mouth. The lungs can also be taken as well.
Then, specialists analyze the sample to determine if it contains the genetic factor of the SK virus. If the virus is found to have a genome or “genome” in the sample, this means that the owner of the sample is a carrier of the disease. But we must pay attention to the fact that the absence of the genetic factor in the sample does not necessarily mean that a person does not carry the virus, since the virus may already be in their body but in other parts from which samples were not taken.
This explains some of the cases that doctors thought they had recovered from Corona, and then the results of their sample tests were positive after discharge. They likely carried the virus all along, but it did not appear in the samples taken by doctors before they were discharged from the hospital, leading doctors to believe that they had recovered.
The chief virology researcher at Charette Hospital in Berlin, Christian Drosten, is compared to trying to catch a fish from a pool using a bowl. By removing the container from the water and not finding the fish inside, it does not mean that it does not
There is a fish in the tank, he said in his “podcast” on the northern German news network “NDR”.
Antibody test
The second group of coronavirus screening tests are antibody tests known as the “ELISA” technique, an enzyme immunological technique that shows whether a person has been infected with the virus in the past.
When the virus infects the body, the immune system accumulates antibodies to fight it. If these antibodies are found in the sample, this means that the person was infected with a crown at some point. This test is done by taking a blood sample from the person, which is then analyzed in the laboratory.
Several companies have produced rapid detection antibody tests, but they must be performed by a specialist doctor.This test is similar to the method of measuring blood sugar, in which it is through a puncture to extract a few drops of blood on a thin slide and add a chemical solution to it and then analyze it. If the antibodies that the body makes against the new corona virus are present in the blood, and are called “IgM” and “IgG”, the color of the sample will change. This means that this person was infected with the virus in the past and had immunity.
But Christian Drosten cautions in his podcast that results are not always guaranteed. Sometimes there is a so-called “cross reactivity”, that is, the interaction of antibodies with another virus similar to the Corona virus. This means that even if the result of this test is positive, the antibodies that make up the body may have been resistant to other respiratory infections of the Coronavirus family, such as a common cold. However, the producers of these tests deny that this happens with their products and confirm the validity of the results.
Who should take the test and when?
The importance of the PCR diagnostic detection test is due to its ability to identify people infected with the virus, which allows them to reach their mixing circle and determine the appropriate isolation procedures for them, either by means of preventive isolation of two weeks or quarantine in more serious cases.
“ELISA” antibody tests help epidemiologists know the number of people who have been infected in the past and who have not been counted in official statistics, and this test also helps to know if the numbers indicate access to a type of “collective immunity” in society. This helps decision makers in countries to take appropriate measures to ease or tighten restrictions.
In addition, the antibody test helps in vaccine tests carried out on volunteers to control the reaction of their immune system, and it is also possible through this test to follow the immune system of people who have already been infected and have become infected. recovered from the crown. In fact, some German university hospitals began using “ELISA” tests on a random sample of participants to find out if they were infected, as well as to study the behavior and evolution of the virus.
Various tests in the states
Countries differ in their treatment of coronavirus testing for several reasons, such as the capabilities of the health systems in each country and the availability of necessary laboratory tests and equipment to carry them out. The behavior of the countries varies in the seriousness of facing the pandemic. South Korea, for example, used its experience to cope with the SARS epidemic in 2002 and was one of the first countries to circulate crown detection early and to as many people as possible, even those without symptoms.
Germany is also one of the countries that conducts a large number of crown screening tests, but is only limited to those that show symptoms or have been mixed with infected people. Other countries, such as the United States of America, are increasing and expanding the number of tests now due to the widespread spread of the virus there. In other countries, such as some African countries, there is almost no testing.
Fabinan Schmidt / S.H / P.
This news is published in a cooperation agreement with DW
[ad_2]
