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Coronavirus (COVID-19) Tests

Since the recognition of the Coronavirus (COVID-19) pandemic, our laboratory has been monitoring all the studies of the American Association of Clinical Chemists (AACC), of which we are a member. All the videos on this page contain up-to-date information on the AACC website showing the stage we are at in the diagnosis and antivirus protection of Sars-COVID-2, that is, COVID-19. Our laboratory, a member of the organization, has translated them into Turkish for information purposes.

What are the coronavirus tests?

The tests currently applied worldwide to detect COVID-19 infection are summarized below for informational purposes.

PCR Testing

This test provides information about the virus's genetic information (Viral-RNA) and whether it has infected the person. This test can only give results at an early stage of infection when the person is actively infected and antibodies have not yet been formed. If the test gives a positive result, the risk of transmitting the virus to others can be significantly reduced by isolating the people having positive results and their environment with whom they had physical contact. Thus, the chain of transmission of the virus from person to person is broken. For testing, samples are taken using the nasal swab. The margin of error in the test results (false-negative results) is around 15-20%. These results may be due to errors in sampling and differences in the applied PCR testing methods.

Serology Testing (Antibody Testing)

This test, applied to the person exposed to the virus, reveals the defense system activated against the virus. If the test result is positive, it is understood that the virus has entered the body in any way. However, the test does not provide information on when antibodies are formed or whether the body has overcome the disease. A negative test result does not mean that the virus is not available since it takes time for the defense system to become active after the virus enters the body. A negative result can be obtained if the defense system is not activated although the virus is in the body. In the first days of exposure to the virus, it is more likely that active infection will not occur and the test result will be negative since antibodies usually start to form one or two weeks after viruses enter the body. However, it should be noted that there is no specific information about when the body's defense system response to COVID-19 occurs. This period may be longer than 1-2 weeks. In addition, as with any virus, the response time of the body's defense system in COVID-19 may vary from person to person. For these reasons, the negative result, unfortunately, cannot give definite information about the absence of COVID-19 infection.

It should be noted that PCR and Serology (antibody) testings are two different applications among all screening tests in the world. Scientists are still researching more accurate and reliable tests for COVID-19.

LFIA (Lateral Flow Immunoassay)

It is a test in which the virus is directly tested from urine, blood, saliva, sweat, serum, and other fluids, and the test results in 15 minutes. For testing, the biological material binds along a strip with antibodies developed for that virus only. As a result of the test, the presence of the antigen (virus) is revealed. In this test, the presence of the virus can be detected by catching the virus itself. However, the test is time-consuming and still has a margin of error.

Rapid Antigen Testing

It is not just a test for COVID-19. It detects all SARS CoV-2 viruses. Therefore, a positive test result does not indicate that there is definitely the COVID-19 virus in the body but that any virus from the SARS CoV-2 family, including COVID-19, is present. However, if this test is positive, treatment can be started immediately without the need for further COVID-19 testing, in case the virus is COVID-19. Thus, no time is wasted. The purpose of the test is to accelerate the diagnosis and treatment processes in the absence of a test for COVID-19. Other advantages of the test are that it results in 2.5 hours, and the risk of contamination and spread from sample handling and processing is very low.

What Tests Are Applied To Detect Coronavirus?

SARS-CoV-2 (COVID-19) PCR testing and IgA, IgM, and IgG antibody (immunity) testings are applied in our institution. PCR is performed with a swab and the antibody test with a blood sample.

As of 28.10.2020, the Ministry of Health has determined our institution as the authorized laboratory to perform PCR testing on people who make an application with the suspicion of COVID-19 (SARS -CoV-2) disease.

Therefore, all our patients who apply with the suspicion of SARS-CoV-2 (COVID-19) can have PCR testing and IgA, IgM, and IgG antibody (immunity) testings done in our institution.

Does the PCR Testing Give an Accurate Result?

Since the PCR is based on the virus's genetic structure, if the result is positive, a definitive diagnosis can be made that the person has an active COVID-19 infection. However, if the result is negative, a definitive diagnosis cannot be made if the person does not have an active COVID-19 infection. The reason for this is some conditions that can cause a false-negative result. These conditions include the inability to sample the swab accurately, the virus moving away from the mucosa, and therefore the active absence of the virus in the sample taken. For this reason, hospitals may repeat the test in two days for people who show symptoms but whose results are negative.

It is also possible that a person with a negative PCR testing result may have contracted the COVID-19 virus after submitting a sample for testing. For this reason, there is no guarantee that the person is not positive when the result is issued.

In summary, PCR testing is valuable in understanding that a symptomatic person has COVID-19; however, a negative result does not necessarily mean that the person does not have COVID-19.

I am not showing any symptoms. Should I get tested for COVID-19?

If the person is showing no symptoms, this can mean two things:

  1. The person is not infected with the virus.
  2. The person was infected with the virus, so the immune system was activated and started to fight the virus.

Currently, no test gives us precise information about the first article. However, whether the person's immune system is active against the COVID-19 virus can be understood by antibody testings. The Ministry of Health has approved private laboratories to perform antibody testings for applicants to respond to the incoming demand.

What is the difference between conventional vaccines (Sinovac, Sputnik, etc.) and mRNA vaccines (BioNTech, Moderna, AstraZeneca, etc.)?

When the SARS Cov-2 infection threatened the whole world in late 2019, the world made efforts to reduce mortality rates quickly. While studies continue to define the behavior, structure, and effects of the virus, the first measure was the application of the conventional vaccination methods. Vaccine manufacturers such as Sinovac and Sputnik have prepared and quickly started using conventional vaccines, known as inactivated virus delivery to humans.

The primary mechanism of action of conventional vaccines such as Sinovac and Sputnik is to create a total antibody against all proteins contained in the biological structure of the virus. The effectiveness of these vaccines is low, and their continuity and protection are controversial; however, vaccines have been effective in reducing mortality rates and slowing the speed of the disease. The effect of the antibodies formed in the body for the inactive virus is more or less the same as the immune response of the people who have fought the disease and had the disease with the transmission of the active virus.

While the vaccine studies are continuing, there has been good news from the BioNTech company founded by Turkish Scientists Özlem Türeci and Uğur Şahin. A Biochemistry Specialist named Katalin Karinko of Polish origin working at BioNTech has developed a new vaccine that acts with the mRNA mechanism. mRNA vaccines are different from conventional vaccines, which allow the formation of total antibodies against all proteins in the biological structure of the virus. It enables the creation of antibodies against the protein on the organelle of the virus called spike. The spike organelle is like a key that allows the virus to attach to the lung cell and multiply there. When this key is taken from the virus, the virus cannot attach to the lung and enter the cell. If it cannot enter the cell, it cannot reproduce. Thus, the virus is destroyed without making the person sick and without fighting the virus. Additionally, the medical industry has also focused on having a protection system to prevent the virus from entering the cell. The vaccines of BioNTech, followed by Moderna and Astra Zeneca, have been designed to act with the mRNA mechanism.

Which antibody test would it be more appropriate for me?

As studies on the recognition of the virus and the development of vaccines continue rapidly, the diagnostic studies for the detection of antibodies in people who have also had the disease in the laboratory have constantly changed and improved. Antibody tests currently available in the world for COVID-19 are IgA, IgM, IgG, and Spike antibody testings. Upon request, people can have any or all of these antibody tests done at the same time. All of the Covid-19 antibody tests are currently available in our laboratory.

The detection of whether the person has been exposed to the virus and the antibody levels in people who have had the disease can be determined using the Elisa methods. Elisa methods provide diagnosis by measuring IgA, IgM and IgG type antibodies synthesized at different stages of infection.

After discovering vaccines with mRNA mechanisms, innovations have been observed in laboratory diagnostic methods. Individuals with mRNA vaccine are expected to form antibodies against Spike protein rather than total antibody due to the different nature of the vaccines described above. For this reason, laboratory kit manufacturers have tended to produce kits that detect only Spike antibody levels, as well as kits for the rapid and healthy detection of total antibodies. After this development, our laboratory has also started to work with the kits necessary for detecting Spike antibodies, as is the case worldwide. Spike antibody levels have also gained importance with introducing the Biontech vaccine in our country. However, since the Sinovac vaccine was first administered, the total antibody test continues to maintain its currency.

Since total antibodies are not expected to form in the body of people who do not have Covid disease and/or have only mRNA vaccine (Biontech, Moderna, Astra Zeneca, etc.), it is not meaningful to perform total antibody studies on these people. The Spike antibody study is sufficient to provide information on antibody levels.

Total antibodies are expected to form in the body of people who have had Covid disease and/or have had a conventional vaccine (Sinovac, Sputnik, etc.). Therefore, the total antibody test helps monitor the antibody level. In addition, Spike antibody testing can also be done since Spike antibodies are also part of total antibodies. Spike antibodies will also provide useful information in terms of protection, as they mean that the virus has created a barrier to entry into the cell. However, the Spike antibody may appear slightly lower than the general antibody. Although this low protection rate causes doubts, we can say that the results give information about protection.

In accordance with the worldwide research on total antibody testing, our current knowledge is limited to the following:

  • IgA antibodies are found in secretions, especially in the mouth, nose, gastrointestinal walls, and respiratory tract. IgA antibodies are the first to encounter the virus and fight it before it enters the blood. If there is a viral infection in an organ that produces secretions such as the mouth or nose, the body's immune system response begins with IgA.
  • IgM antibodies are formed days after the virus enters the body to create a greater immunity, and they are the second-responder antibodies against the virus after IgA antibodies.
  • IgG antibodies are antibodies that occur after or sometimes simultaneously with IgM antibodies. They stay higher in the blood for a more extended period, thus providing longer protection. IgG antibodies indicate that the body has developed a defense system against the virus. In line with the information on previously researched diseases, it is known that IgG antibodies can be preserved for a long time, even for a lifetime, like vaccines. However, it is unknown how long the Covid-19 IgG antibodies remain high in the blood and whether the amount is sufficient to protect the second infection.

If the virus is at a low dose, it may be destroyed by IgA antibodies before it enters the body. However, if the virus is in high doses, the strength of the IgA antibodies may not be enough to prevent the infection. In this case, the rate of IgM and IgG antibodies in the blood are detected, respectively.

In summary, after the virus enters the body:

  • The first respond is IgA;
  • The second respond is IgM;
  • The last respond is IgG, the one that stays high for the longest time.


I have had the Sinovac vaccine. Why is my spike antibody result low?

Total antibodies are expected to form in the body of people who have had Covid disease and/or have had a conventional vaccine (Sinovac, Sputnik, etc.). Since Spike antibodies are part of total antibodies, they may appear to be decently low compared to your general antibody. (Please also read the answers to the above questions to understand the difference between spike and total antibody.) Although the low level causes doubt about the protection rate in the patients, the results provide information about protection since the presence of Spike antibodies indicates that the virus has created a barrier to entry into the cell.

My antibody is positive. Am I protected from the virus?

One of the most frequently asked questions in our laboratory is the interpretation of the antibody values.

Research continues around the world. However, unfortunately, there is no definite information about the level of protection provided by antibodies in the current situation.

A positive result of any total antibody testings indicates that the person has encountered the virus before due to having the disease or getting the inactivated virus with a conventional vaccine.

A positive result of Spike antibody testing may indicate that the person has had the mRNA vaccine or has encountered the virus before.

A negative antibody testing result does not mean that the person has not encountered the virus. Even if the virus has entered the body, negative results may be obtained due to factors such as the quality of the sample taken, the time the person encounters the virus, and the response time of the person's own immune system to the virus.

Studies conducted for many known viruses for years have provided us with sufficient information about the duration of the protection provided by antibodies. However, scientific data on this matter for COVID-19 infection are still insufficient. For this reason, antibody test results can only provide information on possibilities.

Existing research only tells us in what order and why antibodies are formed. Transition times between these antibodies vary according to the immune system's response to the infection and the severity of the infection. In general:

  • It is known that IgG develops 14 days after a person shows symptoms. Accordingly, a positive IgG result may indicate that a person has had an infection 14 days ago or before.
  • Unfortunately, it is not possible to mention the exact day criteria for IgA and IgM. However, IgA and IgM antibody testings can give an idea of the infection in less than 14 days compared to IgG.
  • In case IgA antibodies in the secretion are synthesized at a sufficiently high rate to be detected, these antibodies constitute a valuable diagnostic criterion as the body's first response to a virus infection. It can enable the detection of the virus shortly after a person encounters the virus. However, it should be noted that if the virus becomes indestructible against IgA antibodies, the virus will enter the body, and the IgA antibody will become negative after a while. If this stage has already been passed, performing IgM beforehand or IgG antibody tests later would be more appropriate.

All the tests mentioned above are screening tests. In the current situation, this is all the information that laboratories can provide. Currently, there are no other tests and criteria around the world. However, since Covid-19 research and data can still offer limited information, these tests are also insufficient for an accurate diagnosis. Individuals should decide which test they want to have according to their criteria. Laboratories cannot provide precise information or advice on this subject in accordance with the information described above.

The important thing is to get an answer to the question of at what level we produce which antibody after vaccination or having the disease, depending on the above-described characteristics of the vaccine, to repeat the tests after a certain period, to monitor whether there is a decrease, and to take the necessary measures if any. Test results are not certain about whether you are protected from the disease or not; however, they are informative.

What other tests can I get to detect acute coronavirus?

The following parameters about acute Covid-19 infection can also provide us with information:

  • Lymphocyte count: Reflects the reduced Immunological response to the virus
  • Leukocytosis: Bacterial (super) infection
  • Neutrophilia: Bacterial (super) infection
  • Increase in MDW: Increased Average Distribution of Monocyte Cells. Severe Viral sepsis has been detected in COVID-19.
  • Thrombocytopenia: Increased consumption (DIC=Disseminated Intravascular Coagulation), Protein S and C deficiency, clot formation in blood vessels
  • CRP: Alarm protein that rises rapidly due to infection in the liver
  • Procalcitonin: Bacterial (super) infection. It is a differential diagnosis of bacterial and viral infection.
  • LDH: Pulmonary damage and/or diffuse organ damage
  • AST, ALT: Liver damage and/or diffuse organ damage
  • Bilirubin: Liver damage
  • Creatinine: Kidney damage
  • Cardiac Troponins: Cardiac damage
  • Albumin: Impairment of liver functions
  • PTZ: Activation of blood coagulation and/or disseminated coagulopathy
  • D-Dimer: Increased blood clotting and/or disseminated intravascular coagulation
  • Interleukin 6

For more information, contact us at 444 3 929.

When should I get tested for COVID-19?

If you do not show any symptoms and are unsure whether you have been exposed to the virus, you do not need to be tested. But if you suspect that you have been exposed to the virus, it is better to isolate yourself for 14 days and avoid seeing other people. During this period, you should also constantly monitor yourself for the following COVID-19 symptoms:

  • Fever
  • Fever-like chills and/or sweating
  • Cough
  • Mild or moderate difficulty breathing
  • Sore throat
  • Muscle or joint pain
  • Vomiting or diarrhea
  • Newly developing losses in the perception of smell or taste

If you do not have any of these symptoms after 14 days, you do not need to get tested.

If you have any of these symptoms, the next step is to contact the closest healthcare provider to get tested, just as you would if you had a cold or flu.

If you have mild symptoms, are in close contact with people in a higher risk group, such as the elderly, or one of these people, it is essential to request a test. However, if your symptoms are mild and you are not in contact with vulnerable groups or not among these groups, the healthcare provider you apply to may state that testing is not necessary. This can occur especially when demand for testing is high and local labs need to focus on high-risk cases. In such a case, you do not have to worry. Many people with mild COVID-19 symptoms can recover at home on their own without any medical attention. However, it is essential to avoid contact with others until you have recovered. If your symptoms get worse, please inform your healthcare provider.

If you have been in close contact with someone who has been diagnosed with COVID-19, you should request a test at your healthcare provider even if you are not showing any symptoms. Early testing of people who have been in contact with COVID-19 patients is essential to prevent the spread of the disease before or after symptoms appear.

What precautions do you take for the safety of your patients?

  • In our laboratory, sampling for PCR testing is carried out in a special isolated section, without contact with routine patients and the internal environment of the laboratory. Patient entrances are organized to be externally connected to the laboratory to ensure the safety of our other patients who apply to our laboratory.
  • The section where the sample is taken is disinfected before and after each patient, and the samples are taken only at certain time intervals.
  • Certified organizations constantly disinfect our building.
  • Thermal camera control is carried out at the entrances to the building.
  • All environments are equipped with materials necessary for hand and body hygiene.