What is the difference between an antigen test and an antibody test?

Antigen tests for Covid-19 can tell you whether you are currently infected with the virus, while antibody tests check whether your body has developed antibodies to fight off a future infection.

If you want to check whether you have Covid-19, either as a routine precaution or because you are experiencing symptoms or have been in contact with a positive case, you can take an antigen test. Antigens are proteins found on the surface of a virus and antigen tests work by detecting their presence in a sample taken from the nasal cavity and/or the back of the throat.

In contrast, antibody tests are not used to detect an active infection. Instead, they can tell you whether your body has successfully developed antibodies to help protect you from a future Covid-19 infection.

Antibodies are designed to recognise and attack pathogens so you either don’t become ill in the first place, or you recover more quickly. Used by the immune system as a vital part of the body’s defence system, antibodies are able to detect antigens that they have encountered before.

A Covid-19 antibody test is able to tell you whether or not there are Covid-specific antibodies in your bloodstream. You may have these antibodies either from experiencing a coronavirus infection or from receiving a dose of a vaccination.

An antibody test cannot tell you whether you currently have Covid-19, that is the role of an antigen test. In fact, an antibody test should not be taken for at least 14 days after a positive test result or a vaccination.

How do the tests work?

AlphaBiolabs offers both Covid-19 antigen and antibody tests and they can be ordered online.

Our non-invasive antigen lateral flow test is for professional or business use and will produce a result within 15 minutes using a portable immunoassay device. After collecting a sample of your cells with a simple nasal swab, the test will tell you whether or not Covid-19 antigens were detected.

The test is simple to use and the results are displayed in a similar way to a traditional pregnancy test. If the test has detected an active coronavirus infection, it will show two lines. But if the result is negative, only one line (the control line) will be visible.

If you get a positive result from a lateral flow test, it is recommended that you follow up with a PCR test, which involves sending a swab sample to a laboratory for analysis.

Our rapid antibody and immunity test works in a similar way.  Again designed for professional and business use, it also uses a lateral flow device (LFD) and displays two lines for a positive result. But instead of taking a nasal swab, you will need to collect a small sample of blood using a finger-prick test and add this, together with a couple of drops of buffer solution, to the device.

If Covid-specific antibodies are detected in your blood sample, two red lines will be displayed in just 10 minutes. The rapid test can tell you if antibodies are found, but it will not give you an indication of the levels detected in your sample.

AlphaBiolabs also offers an advanced laboratory antibody and immunity test, which can give you a quantitative result and tell you whether your antibody levels are low, medium or high. This can give you an indication of how effective your immune system will be at fighting off a future Covid-19 infection, although even high levels of antibodies cannot guarantee that you won’t catch the virus.

When you order this test, you will be sent a sample collection kit that you can use to collect a small amount of blood. You will then need to send it to our UK-based laboratory for analysis using the pre-paid envelope provided.

Your results will be emailed to you within three days of our laboratory receiving your sample for testing.

As well as providing antibody and antigen tests to the general public, AlphaBiolabs also offers workplace testing for employers wanting to minimise the risk of Covid transmission among their workforce.