Blood antibody tests to tell if you have had a COVID-19 infection

Colin Garner ANTRUK announcements, Coronavirus COVID-19

It has been announced today by the UK government that Public Health England has evaluated Roche’s antibody test ( for detecting if a person has been infected with COVID-19 and have approved the use of the test for general population screening. Roche are the world’s second largest pharmaceutical company and are acknowledged as world leaders in diagnostic testing.

The test is what is known as a serology test and looks for antibodies in the blood against COVID-19. A person’s immune system when confronted by virus responds in a number of different ways. The first response is to use antibodies circulating in the blood to fight the attacker. This response is called innate immunity meaning that it is there all the time. Innate immunity through a class of antibodies called IgM is the first response to any infectious agent whether this be a virus like COVID-19, an antibiotic resistant bacteria or a fungal infection. Whilst the first line of defence is being fired up, a second antibody defence mechanism comes into play which is called acquired immunity. Acquired immunity can take 2 – 3 weeks to come into full effect and uses a different category of antibodies called IgG and IgA. Acquired immunity is what will protect from the same infectious agent if we are confronted with this infectious agent in the future. It is what might protect someone who has had a COVID-19 infection getting it again. However. it is still unknown currently if a person who has been infected with COVID-19 can get another infection in the future.

I provide this explanation as a way to understand that the Roche antibody test kit appears to be able to measure all three classes of antibody against COVID-19 ie IgM, IgG and IgA. Hospitals and reference laboratories can run the test on Roche’s cobas automated analysers, which are widely available around the world. These fully automated systems can provide SARS-CoV-2 serology test results in approximately 18 minutes for one single test, with a test throughput of up to 300 tests/hour, depending on the analyser. As an aside COVID-19 vaccines are designed to induce the same antibody response so that the body can fight off COVID-19 infections.

Roche’s antibody test kit was made available in the USA on 4 May 2020 (see This is my personal opinion, but I am not sure why it has taken the UK another 10 days to announce their test findings when the test takes 18 minutes? Each day without antibody information is another day lost in the COVID-19 battle.

Finally, I must point out that we have very few diagnostic test kits for drug-resistant bacterial infections which can arise alongside viral infections and yet such test kits are needed to optimise antibiotic treatment. We need to identify the antibiotic resistant bacteria that someone is infected with as well as finding the right antibiotic for treatment (right bacteria, right antibiotic, right dose, right person) (see the links between COVID-19 and bacterial infections

Note: Another diagnostic test kit manufacturer Abbott, USA also has an antibody test that has gained approval in the USA and EU (