COVID-19 Testing: PCR (Diagnostic) vs Antibody

29th June 2020

COVID-19 Testing: PCR (Diagnostic) vs Antibody

COVID-19 Testing: PCR (Diagnostic) vs Antibody

The advice from the World Health Organisation in relation to the COVID-19 pandemic has been simple; Test. Test. Test.

But what are the different types of COVID-19 tests and what are they used for?

 

Diagnostic (PCR) Testing

This type of testing detects SARS-CoV-2 (the virus that causes COVID-19) within the body and will tell you if you currently have COVID-19. PCR tests cannot tell you if you have had past infection.

Sample collection for a PCR test can vary, though it is usually in the form of a swab, which will gather an individual’s nasopharyngeal (nose and throat) secretions.

PCR tests for COVID-19 all use methods that detect a specific part of the viral genome – for example Viral RNA or Antigen.

A sample is prepared by extracting the chosen section of the genome, and then PCR (Polyamerase Chain Reaction) techniques are used to amplify (replicate) the genome section, ready for detection.

Viral RNA Tests

This type of test detects the RNA (Ribonucleic acid) contained within the SARS-CoV-2 virus.

It is this type of test, for RNA, that is recommended by The World Health Organisation for COVID-19 diagnosis.

Antigen Tests

Antigens are molecular structures on the surface of viruses that are recognized by the immune system and are capable of triggering an immune response.

Antigen tests detect the presence of the SARS-CoV-2 virus by looking for the antigen on the surface of the virus.

Randox COVID-19 Test

The Randox COVID-19 test, as recommended by the World Health Organisation, detects the RNA contained within the SARS-CoV-2 virus.

After sample extraction and amplification, the virus is detected on our patented Randox Biochip Technology platform.

The Randox Biochip, which can run multiple tests simultaneously, performs two tests for COVID-19 – one specific and one confirmatory – as recommended by the WHO. This delivers extra assurance of the correct diagnosis and avoids the need to repeat the test.

 

Antibody (Serology) Tests

Antibody (also known as serology) tests, are usually performed on a patient blood sample, and look for antibodies (a type of protein) that may have been developed by the patient’s immune system to fight off disease.

If present, antibodies may provide a degree of immunity for the patient against COVID-19 in the future.

However, there is still much unknown about the body’s antibody response to COVID-19, including;

  • Whether all patients who have been infected with SARS-CoV-2 will generate antibodies (recent studies and news reports indicate that this isn’t the case. Click here for an example.)
  • Whether those who have had more severe symptoms as a result of COVID-19 will produce more antibodies than those who had mild symptoms, or were asymptomatic.
  • If antibodies from other coronaviruses previously experienced by the patient may be enough to fight off the virus, therefore eliminating the need for COVID-19 specific antibodies.
  • How long any COVID-19 specific antibody response will last for.
  • How much future immunity is provided by COVID-19 antibodies. Will it prevent the patient from being infected, or will future infection just be less severe?

If antibodies for the SARS-CoV-2 virus are present this can give an indication that the patient has been previously infected with COVID-19. Antibody tests do not confirm the real-time presence of the virus in your system.

For example, a negative antibody result does not necessarily mean the body has not been exposed to the SARS-CoV-2 virus. It could in fact, be currently infected, but has not yet generated antibodies. A diagnostic test will confirm current presence of the virus.

 

Therefore, it is recommended that antibody tests are used in tandem with a diagnostic test to determine a complete overview of the patient’s COVID-19 status.

Randox Health currently offers both diagnostic testing and antibody testing for SARS-CoV-2 (COVID-19).

A combination of diagnostic and antibody testing is available for individual purchase, or as part of our ‘Back to Business’ COVID-19 testing service, for staff screening.

Click here to find out more.

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