Will you share my Coronavirus results with Public Health England (PHE)?
We are not bound to share results from the coronavirus antibody test with the Public Health England (PHE), as this test is for past infection. We hope to support the PHE in the future by contributing fully anonymised data, that will help them to better understand the scope of the pandemic.
Could there be false negative results?
The Abbott coronavirus antibody test was 100% sensitive in its validation study. This means that it correctly detected antibodies to SARS-CoV-2 in all samples from people with a confirmed coronavirus infection and who were tested at least 14 days after the onset of symptoms. If you test before this time, you may get a negative result even if you are infected, because your antibodies may not yet have reached detectable levels. There may be scenarios where an antibody test is negative but the individual has been infected with coronavirus. See below for further details.
Can I get a negative antibody result even if I have had covid-19 infection?
There is a small possibility that you have had coronavirus yet have not developed antibodies. This can happen if you had a very mild case of COVID-19 or did not develop any symptoms. There is also some emerging evidence that a minority of people who had a negative antibody result may have had a different type of immune response controlled by T cells, a type of white blood cell that recognises infected cells. Our test measures IgG (immunoglobulin G antibodies) which is the most common type of antibody found in the blood after an infection. As our immune systems are highly complex and this virus is novel, it takes time for the global medical science community to develop the best understanding of COVID-19 immunity. More recently research from the Karolinska Institutet in Sweden found that people with mild or no symptoms had developed “T-cell” immunity despite testing negative for antibodies. This study is yet to be published and peer reviewed by the science community, but it has no doubt provoked further debate about how our immune systems respond to the virus. Before we can jump to any solid conclusions, further evaluation of this is needed with more research. Until we know more about whether antibodies or T-cells confer any protection against coronavirus, it is not safe to assume that you have acquired immunity to COVID-19.
Is my negative test result reliable if my suspected infection was over 2 months ago?
If you develop an antibody response to the virus, it is most likely to show up as a positive result 2-3 weeks after the onset of symptoms. Further research is currently being conducted to confirm what happens to these antibody levels beyond 5 weeks. At present we are not in a position to reach any clear conclusions as whilst some studies have shown the antibody response can disappear after 2-3 months, others have concluded this can last for longer than 2 months. In short, a negative antibody result cannot completely rule out a previous infection.
Since the first case of COVID-19 was first reported to the World Health Organisation in December 2019 knowledge about this virus has been ever evolving. Research is ongoing and there is still much more to learn about the long-term effects of this virus on our health and immunity. It is also important to note that amidst our focus on this pandemic we must not forget that the symptoms of coronavirus can be caused by other viruses, allergies and medical conditions. If you are still experiencing symptoms which cause you concern, we recommend you discuss them with your GP.
What does a borderline result mean?
Some laboratories also report borderline results. Borderline results mean that IgG antibodies were not high enough to give a positive result. This may be because you tested too soon after developing symptoms. If you get a borderline result, we suggest repeating the test 7-14 days after your first test to check if your antibody levels have increased.