In the Chinese city of Wuhan in late 2019, after the spread of the SARS-CoV-2 virus and caused a global pandemic, the medical world took action.
After the emergence of a new coronavirus, virologists around the world began to use different methods to diagnose patients.
There are three main methods for diagnosing the disease in the short term:
• Polymer Chain Reaction (PCR) test
• Computed tomography of the chest to detect the problem of "ice glass" in the lungs caused by coronavirus
• Serological tests
The PCR method is performed by taking a sample from the throat or nose of people who are suspected of being infected with the coronavirus. It aims to detect antibodies in the active phase of the virus when symptoms of the disease appear. This is usually done in the first week after infection.
Computed tomography is used by Chinese doctors as an emergency diagnostic method immediately after the spread of the coronavirus. However, it turned out later that this is the least inaccurate method.
Serological tests are performed by taking blood from a finger or a vein to determine if the person has been in contact with sick people and if he or she is infected. The name of the method is derived from the Latin word "serum". In the laboratory, the blood is mixed with the appropriate recent. If there are antibodies in the blood, it changes color recently.
Unlike the previous two methods, serological tests focus on detecting antibodies regardless of symptoms and help determine if a person is immune to the disease. That is, both active patients who have not been diagnosed by PCR and those who have already recovered, as well as asymptomatic carriers of the coronavirus, are studied. The latter are also called "super spreaders". Although the exact extent of infection in this category of individuals is not yet known, the detection of coronavirus in the absence of severe symptoms is important both in identifying asymptomatic carriers and in the pre-symptomatic stage of the disease.
Thus, this method is important in assessing both the disease and the population's protection against coronavirus. Thus, it is possible to develop effective measures against the epidemic.
However, the presence of antibodies does not guarantee the possibility of re-infection with the coronavirus. This issue has not been clarified yet. Recent studies show that the number of antibodies decreases sharply three months after the disease. In other words, the resistance of patients may be unstable. This is taken into account when preparing the vaccine. Perhaps some time after vaccination, the antibodies will disappear and you will need to be vaccinated regularly.
In this regard, vaccine manufacturers are focusing on the development of drugs that stimulate T cells, the second tool of human resistance, along with antibodies. Unlike the latter, T cells remain in the body for a long time and thus can respond effectively to re-infection with the coronavirus.
In addition, serological testing is important for the treatment of coronavirus. One treatment may be plasma transfusions of already infected patients. This method has previously been shown to be effective in combating the disease in the absence of drugs and vaccines.
Finally, coronavirus mortality and mortality statistics can be used to estimate mortality, ie the risk to the human population.
Serological tests are divided into three types according to recurrence criteria and test objects:
• individual tests
• Repeated tests in a specific area to assess the dynamics of the disease
• Repeated tests in the same people to assess the stability of the current immune system and predict whether the antibodies will protect against disease in the future. Repeated tests reduce the likelihood of error, but complicate the examination procedure.
Potentially, serological tests can help assess immunity to coronavirus in a particular community and society in general. In principle, this is important for the abolition of quarantine and the return of people to normal life. Therefore, ideally, a general study of high-risk groups (doctors, the elderly, etc.) is recommended. However, frankly, this is not possible due to practicality (high cost and lack of technical capabilities) and ethics (people's right to choose whether or not they know the state of their immune systems).