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Rapid Response COVID-19 Tests

Invisio now stocks the new Rapid 15-Minute COVID-19 Antigen test kits, and we have provided some information below to answer some questions about what these kits are, and how to use them. 

These tests are only on sale to medical professionals - please get in touch with us directly to order in bulk as these are not available for sale to retail customers


What are lateral flow tests (LFTs)?

Lateral flow tests (LFTs) are a common type of diagnostic test and have been around for many years. They are beneficial on account of being cheap, easy to mass produce, can be self-administered, provide results in a matter of minutes and have high accuracy when performed correctly.

The most well-known lateral flow test is probably the pregnancy test.

Recently LFTs have been applied to coronavirus testing, in an effort to minimise the spread of SARS-CoV-2, the virus which causes the disease known as COVID-19.

What is the rapid SARS-CoV-2 antigen diagnostic test?

The COVID-19 diagnostic test (the SARS-CoV-2 antigen lateral flow test) is an LFT that detects SARS-CoV-2 viral fragments (antigens).

Similarly to the pregnancy test, the COVID-19 diagnostic test has two labelled antibody detection lines: a test line and a control line which both are invisible at the start of the test, but will become visible once the test is completed.

At the end of the test, if both the control and test lines are visible, this means the test is positive for SARS-CoV-2.

If the control line is visible but the test line is invisible, then the test is negative for SARS-CoV-2.

If the test line is visible but the control line is not, or if neither line is visible, this means the test is invalid and should be retaken.

How Do COVID-19 Diagnostic Tests Work?

The principle behind the operation of the COVID-19 diagnostic test is the same as any LFT. The only facet that really changes is the method by which the tester extracts the test component.

In the case of the pregnancy test this process is simple and the user simply needs to provide a urine sample as the test is only looking for a hormone that is present in the urine of pregnant women (human chorionic gonadotropin).

However, in the case of the COVID-19 diagnostic test (SARS-CoV-2 antigen test) the extraction method is a bit more complicated. This is because we need to extract a specific fragment from of a complex virus particle. Specifically, the test is looking for the SARS-CoV-2 antigen, i.e. the protein spikes on the surface of the virus particle (the virion).

To do this, the sample is extracted and placed in a buffer to break up the virus into fragments, which enables it to flow across the test strip and bind to the labelled antibodies.

The procedure for the COVID-19 diagnostic test is as follows:

  1. A swab sample is taken from the nose and/or mouth of the person being tested to extract samples of the virus (if present)
  2. The swabbed sample is placed in a buffer solution which extracts breaks up any virus present on the swab into fragments
  3. Buffer solution is then applied to the test zone of the lateral flow test and is drawn down the length of the test strip
  4. If there is virus present, the virus fragments will bind to the labelled antibodies, which are located below the test lines.
  5. The labelled antibodies (with and without bound virus) are then lifted and drawn further down the test strip to the fixed antibodies at the test zone (test line) to which the virus-bound antibodies bind.
    • The presence of SARS-CoV-2 virus antigen is indicated by a visible line at the test line.
  6. The labelled antibodies without bound virus continue to be drawn down the test strip and bind to the fixed antibodies of the control zone (control line)
    • The presence of unbound antibodies at the control zone (showing that the test is valid) is indicated by a visible line at the control line.

What COVID-19 diagnostic tests do Invisio offer?

We offer a range of COVID-19 diagnostic test (SARS-CoV-2 antigen tests) including:

  • Healgen
  • Siemens
  • Noviral
  • Abbot
  • Wondfo

We hope that this information has been useful. Invisio provide diagnostic kits including those supplied to the NHS.

If you require more information about our COVID-19 diagnostic kits, please enquire here.