​COVID-19 Testing FAQs

What is the difference between PCR (Antigen) and Antibody testing?

Viral swab (PCR) tests check to see if you currently have the virus, if the virus was present when the sample was taken.

The COVID-19 PCR test is a throat and nose swab which tests for the active virus, if this is positive then you are infectious to other people and can spread the infection to those around you.

This test is relevant when people who have been isolating wish to return to their household, community or workplace and need to know that they aren’t infectious.

Antibody tests are used to detect antibodies to the COVID-19 virus to see if you have previously had the virus. The test works by taking a blood sample and testing for the presence of antibodies to see if you have developed an immune response to the virus.

Polymerase Chain Reaction (PCR) testing for viral antigen:
Do I have the virus infection now?

  • Upper respiratory tract sample(s): throat swab, or nose swab, or a combined viral throat and nose swab into one pot of viral transport medium (VTM).
  • VTM media inactivates the virus once swab placed into it, minimising risk of transmission once sampled. Testing Details:
  • PCR test is used to directly detect the presence of the antigen in an active infection.
  • Detects viral RNA present in patient – Only works if patient is infected with virus and sample is collected at the time.
  • All kits used are CE marked kits, approved for use & highest specificity and sensitivity.
  • Best tested 1-5 days after infection.
  • Samples can be posted as a Category B (UN3373) with necessary packaging, if required.

Covid-19 IgG Antibody Test by ELISA:
Have I had the virus?

Antibody testing allows you to understand whether you have the IgG antibodies for COVID-19. Following recent advice from the MHRA antibody testing must be undertaken by a venous blood sample. IgG antibodies develop in most patients within 7 to 10 days after symptoms of COVID-19 begin. IgG antibodies remain in the blood after an infection has passed. These antibodies indicate that you may have had COVID-19 recently and have developed antibodies that may protect you from future infection. It is unknown, at this point, how much protection antibodies might provide against reinfection.

The antibody test should be undertaken ≥ 12 days after your first symptom.

A negative result means that there are no antibodies present at the time of the sample being taken.

A positive antibody test will tell you whether you’ve previously had the virus that causes COVID-19 and that your body has produced an immune response.

  • Specificity - 99.24 % (the probability of the assay of scoring negative in the absence of specific IgG antibodies).
  • Sensitivity – 100% (the probability of the assay of scoring positive in the presence of the specific IgG antibodies ≥12 days post symptom onset).
  • CE registered.
  • Samples can be posted as a Category B (UN3373) with necessary packaging, if required.

Have any more questions? please contact our team via covid@forensic-testing.co.uk

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