Antibody tests are used to detect antibodies to the COVID-19 virus to see if it’s likely that you have had the virus before. The test works by taking a blood sample and testing for the presence of antibodies to see if you have developed an immune response to the virus. Antibody tests differ to virus swab tests, which test to see if you currently have the virus. An antibody test cannot test if you currently have the virus.
The NHS have posted a useful video on how to collect a blood sample here.
What kind of test is this?
This test helps to establish whether someone has had COVID-19 by detecting the specific antibodies to the virus. Our antibody test measures IgG and IgA antibodies against SARS-CoV-2, the virus that causes COVID-19. The test is conducted from serum (SST tube, no centrifuging necessary) at the laboratory and a laboratory report is provided. Seroconversion takes place with almost 100% certainty after around three weeks.
IgA is commonly seen as more immediate, and reflects antibodies along the mucosal membranes. IgA may appear after 3 days (some reports), but more likely after 10 days. IgG is the long-term antibody that appears later, and traditionally indicates a degree of immunity (though this is still being studied in the case of this new virus). By 14 days after the onset of the virus antibody levels are reliably detectable in most people.
Purposes that antibody testing can serve:
- Make a differential diagnosis to distinguish the infection from other acute pulmonary infections such as influenza
- Provide diagnostic assistance in the case of fresh infections
- Document current or past infection ~ 2 – 3 weeks after the onset of symptoms
- Track immune reactions in patients with a confirmed infection
- Possibly document potential immunity if a patient only has positive IgG antibodies
Please note that the test for IgA antibodies in particular is not suitable for screening asymptomatic subjects
How is the test carried out?
This is a finger prick blood test using CE-marked components.
How do I send my blood sample?
A Royal Mail Tracked 24 return label is provided with every kit for you to return to our centre. Covid-19 antibody tests can be returned via any Royal Mail postboxes.
Is your laboratory safe and approved?
Our antibody tests are performed by one of the UK’s leading laboratories who are accredited to ISO 17025.
I am a key worker. Do I get priority to order a test?
We appreciate that a large number of people will want to take our test. We are dealing with each and every order as a priority. Please be rest assured that Check My Body Health are committed to testing at scale and want to help as many people get back to normal life as soon as possible.
How accurate is the test?
IgA 87.5 – 100%
IgG 83.5 – 97.5%
The antigen (S1 domain) used in the test is particularly appropriate for the serological detection of SARS-CoV-2 antibodies as it is more specific than the N or full-length S protein please see the scientific paper “SARS-CoV-2 antibody responses in COVID-19 patients”, for further details, and the other references provided.
IgA & IgG antibodies test is 89 – 100%
What results could your report tell me?
Your test results will be described as either negative, borderline or positive. A positive or borderline result does not mean that you won’t catch the virus again or carry and transmit the virus onto someone else, nor does not mean that you are immune to having another COVID-19 infection in the future.
Is it the same as the at-home rapid detection antibody tests?
No. In order to get the results from this test you collect a finger prick blood sample at home in a small vial. You post this sample to our ISO 17025 accredited laboratory for analysis. Once the laboratory receives your blood sample, your result should be available within 24 hours.
Who should use this test?
This test is appropriate for anyone over the age of 18 who wants to understand whether they have had COVID-19; this means individuals who experienced mild or moderate symptoms, or those who were exposed to COVID-19 but did not experience symptoms at all.
When should I take the test?
It is important to wait 14 days from the onset of symptoms before taking this test. This is to ensure that antibody levels are detectable. If you did not experience any symptoms but were exposed to the virus this test should be taken 21 days after the last exposure.
Who is this test not suitable for?
It should be noted that the test may not accurately detect antibodies in those with a compromised immune system as their production of antibodies is weakened or slower. This may affect individuals with immunodeficiency disease such as HIV or those taking medications that suppress the immune system.
Does this test tell me that I currently have the COVID-19 virus?
No, this test detects antibodies; these are produced some time after an individual becomes infected. In the majority of people antibodies reach detectable levels 14 days after the development of symptoms or, if you haven’t had symptoms, 21 days from possible exposure to the virus.
How soon are antibodies present in my blood?
For most accurate results we recommend taking your blood sample 21 days post onset of symptoms.
What is the NHS coronavirus helpline?
Do not go to a GP surgery, pharmacy or hospital. Use the 111 online coronavirus service to find out what to do.
Only call 111 if you cannot get help online.