Covid-19

ABOUT COVID 19

The diagnosis of Covid -19 caused by the SARS-CoV-2 virus, fever, headache, cough, impaired smell and taste, some symptoms and examination findings such as fatigue, weakness, body aches, X-ray findings, Covid-19 PCR, Covid- 19 antibodies and other laboratory tests.

Laboratory tests for Covid-19 Disease can be done to detect the virus directly, as well as by showing the specific antibodies that the body has created against the virus;

1. PCR TEST that detects the virus itself (viral ribonucleic acid [RNA])
2. ANTIBODY TEST, which detects the body’s response to the virus (serological antibodies)

Contents

• What is a PCR test?
  • When does the PCR test result come out?
• What is an antibody test?
  • How is the antibody test done?
  • Is antibody testing alone sufficient for diagnosis?
• How should the Covid-19 Antibody test results be evaluated?
  • NEGATIVE TEST (< 1.40 NEGATIVE):
  • POSITIVE TEST (>=1.40 POSITIVE):
• What is the COVID-19 Rapid diagnostic test?
• What are the situations in which the use of antibody tests is recommended?
• Are rapid diagnostic tests safe?
• Should a Covid-19 PCR negative result be trusted?
• The following factors may cause a negative result in an infected individual:
• What should be done with a positive result of Covid-19 PCR?
• Clinical Significance of PCR and Antibody Test Results

What is a PCR test?

For the test, firstly, a sample is taken from the patient’s nose and throat by swab method with special sticks. The swab samples taken are delivered to the laboratory where the test will be performed in special liquids, also known as virus transport media. It is done by detecting Covid-19 virus RNA through nucleic acid amplification using the polymerase chain reaction (PCR) method.

• If the result is NEGATIVE, no Covid-19 (SARS-CoV-2) virus material could be detected.
• If the result is POSITIVE, Covid-19 (SARS-CoV-2) virus material has been detected.

When does the PCR test result come out?

Although it results in 3-4 hours depending on laboratory conditions and test intensity, it may take up to 1 day as the test may need to be repeated.

What is an antibody test?

Antibodies are protein-structured immunoglobulins that help the immune system recognize and eliminate threats to the body itself. Our immune system also creates certain antibodies to protect against the Covid -19(SARS-CoV-2) virus.

How is the antibody test done?

With the Antibody Immunity Test, Covid -19 virus Specific IgG antibodies are measured in the blood sample with reference methods in autoanalyzers in the laboratory. Although it varies according to the working days and sessions of the laboratory, it results on the day the blood sample is given. This test result shows whether the person is infected with the Covid-19 virus or whether IgG antibodies develop in people who are infected with the virus or who have recovered from the disease. It is predicted that the Covid-19 incubation period is 5 days and this period can vary between 2-14 days. Therefore, IgG antibodies are also detected as positive in 11-14 days.

Is antibody testing alone sufficient for diagnosis?

The Covid-19 Antibody test, together with the clinical picture, the Covid PCR result, and other laboratory tests, can be used to aid in the diagnosis of Covid infection. The results of the Covid -19 Antibody test should not be used alone for diagnosis. The persistence of Covid-19 IgG antibodies allows the identification of people who have been infected in the past, have recovered, and possibly become immune. It is not known exactly whether people who have been infected with SARS-CoV-2 and subsequently recovered will be fully or partially protected from SARS-CoV-2 infection in the future, or how long the protective immunity will last.

IgM about 7 days after infection,

On the 14th day, IgG can be detected as positive.

IgM until about day 21,

IgG remains positive for a longer time (40 days or more).

What are the situations in which the use of antibody tests is recommended?

1. As a test to support the diagnosis in people with negative PCR test despite clinical findings,
2. Along with PCR test in contact follow-up,
3. In planning the working order of high-risk groups,
4. It is used in the preparation of Immune Plasma Therapy.

Clinical Significance of PCR and Antibody Test Results