What do my antibody results mean?
What does a positive antibody test result mean?
A positive antibody result likely means that an individual has generated an IgG antibody response to SARS-CoV-2 (the covid-19 virus).
How accurate are the results?
You can be highly confident that the results are correct. Specificity concerns the false positive rate and is expressed as a percentage. The antibody test has a 99.63% specificity. This means that out of every 10,000 people tested, 37 (0.37%) will be incorrectly identified as having antibodies to covid-19 when they do not (false positive).
Note that the antibody tests were developed for use and have been validated on venous blood samples (blood taken from a vein by a medical professional) rather than samples of blood taken from a fingerprick. This may affect the accuracy of the test. This is why we recommend having a medical professional take your blood sample, which can be done at home or in the clinic.
Do the antibodies provide immunity to covid-19?
We hope so but we do not know for certain if the antibodies are protective. Based on our knowledge of immunology and similar coronaviruses, it is likely that the antibodies will afford protection. The World Health Organisation (WHO) has stated, “We expect that most people who are infected with covid-19 will develop an antibody response that will provide some level of protection.”
However, until we know more, it is crucial that you continue to follow all relevant government guidance related to social distancing and measures against contracting or spreading covid-19. Please follow the latest most up-to-date government advice, which can be found here: https://www.nhs.uk/conditions/coronavirus-covid-19/ . If you need further advice, feel short of breath or have concerns you are not coping with the illness, please contact 111.
What does a negative antibody test result mean?
A negative test result means that the IgG antibodies to the virus that causes covid-19 were not found in your sample. This may be for the following reasons:
How accurate are the results?
Sensitivity concerns the false negative rate and is expressed as a percentage. The antibody test has a sensitivity of 100% when tested at least 14 days after your first symptoms. Put another way, 14 days after symptom onset, every person who has been infected by covid-19 and developed antibodies is identified as positive by this test (there are no false negatives). This means that your result is extremely likely to be correct if you took the test at least 14 days after symptom onset. If the sample was taken earlier than 14 days, repeat testing may show a positive result once this period has passed.
Note that the antibody tests were developed for use and have been validated on venous blood samples (blood taken from a vein by a medical professional) rather than samples of blood taken from a fingerprick. This may affect the accuracy of the test. This is why we recommend having a medical professional take your blood sample, which can be done at home or in the clinic.
Some research suggests that some individuals have been infected by covid-19 but do not produce detectable IgG antibodies. They may clear the virus by other parts of the immune system, which is not detected by this test. Studies are ongoing.
It is crucial that you continue to follow all relevant government guidance on social distancing and measures against contracting or spreading covid-19. Please follow the latest most up-to-date government advice, which can be found here: https://www.nhs.uk/conditions/coronavirus-covid-19/ . If you need further advice, feel short of breath or have concerns you are not coping with the illness, please contact your GP or 111 via their website (https://111.nhs.uk/). Alternatively you may call them on 111. If you feel extremely unwell, please call 999