Coronavirus Antibody Blood Test
Is it for you?
It is not yet known what level of antibodies gives you immunity to coronavirus or to what extent previous infection provides immunity from future infection.
- COVID Antibodies
COVID Antibodies (2 Biomarkers)
From the expert
The coronavirus antibody home blood test is a new laboratory test that measures the level of antibodies in your blood. It is called the Roche Anti-SARS-CoV-2-S coronavirus antibody test. You can use this test to monitor your antibody levels over time so that you can record your own unique response to the virus or the vaccine.
Your result will lie on a scale between 0.4 units per millilitre (U/ml) and 2,500 U/ml. A result below 0.8 U/ml means that the lab did not find antibodies in your sample. A result above 0.8 U/ml means that antibodies were detected, so you likely have had coronavirus (or have been vaccinated).
It is possible to get a result below 0.8 U/ml even if you have had a coronavirus infection in the past. This could be because you only experienced mild (or non-existent) symptoms. It could also be because your body responded to the virus using different parts of your immune system.
There is a higher chance of a negative result (below 0.8 U/ml) if you take this test too soon after becoming infected with coronavirus or being vaccinated. This is because your body may not have had time to produce antibodies. We recommend waiting at least three weeks after a known infection or vaccination before taking this test.
If you would like to monitor your antibody level over time, we recommend taking a test every 3-4 months. A number of studies have shown that coronavirus antibodies remain in the blood for at least 6-8 months for most people. For some people (particularly those who had no symptoms), antibody levels may decline more quickly.
Your anonymised data may be used to help UK public health agencies (including Public Health England) and other organisations understand the spread of coronavirus within the UK population.
Medichecks uses a CE marked Roche coronavirus antibody test called the Elecsys Anti-SARS-CoV-2 S assay. The manufacturer (Roche) carried out a study to support the CE mark submission of this test. The study used blood samples from patients with a positive coronavirus infection. Roche did not use samples from people without symptoms, so the results may have differed if the study had included these people.
Test sensitivity is the ability of a test to correctly detect a positive result when testing samples from people known to have had a coronavirus infection. Sensitivity can increase from the point of a diagnosis because antibody levels increase in response to an infection. This means that from 21 days after a positive diagnosis (the earliest point at which we recommend testing), the test returned a positive result in 98.3% of cases. After 28 days, sensitivity is 100%, based on Roche’s study.
Test specificity is the ability of a test to correctly produce a negative result when testing samples from people known not to have had a coronavirus infection. Roche used 5,991 negative samples (which were collected before October 2019). The test produced only one false-positive result – giving the test a specificity of 99.98%.
This test may not accurately detect antibodies in people who have compromised immune systems because their antibody response may be slower or weakened. This includes people with immunodeficiency diseases, infections such as HIV, or those who take medications that suppress the immune system. This may also affect the sensitivity and specificity of the test.
A negative antibody result cannot exclude a current infection. If you have been recently exposed to a coronavirus (such as SARS-CoV or COVID-19) the level of antibodies in your blood may not have yet reached levels which are high enough for this test to detect.
This test is only available as a home finger-prick kit. This is because clinic and nurse services are not permitted to collect venous samples for coronavirus antibody tests unless they are covered by UKAS accreditation. As our laboratory is UKAS accredited, we are able to offer this test with a self-collection finger-prick kit.
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