Understanding COVID-19 Antibodies Testing
Using a small blood sample, the antibody test is useful for determining who may have developed IgG/IgM antibodies and presumed exposed and recovering from either a natural infection to, or by vaccination against this SARS-CoV-2 virus.
An immune response can be detected approximately 7 days after infection or vaccination in individuals.
It is unclear how long IgG antibodies are detectable but at this time studies suggest it’s only months after an individual becomes naturally infected with the SARS-CoV-2 virus.
Studies from vaccine efficacy are showing antibodies being present soon after the first shot of vaccine and the second shot serves as a booster for the body to continue to mount an antibodies response.
Today, we cannot yet draw the conclusion that long-term immunity against COVID-19 exists with the presence and later absence of IgG antibodies.
The good news is to date most people who have been infected once have not experienced a recurrence to COVID-19. A vaccination series will support further immunity for those who have had COVID-19.
Presently, the 2020/21 vaccines appear to be effective against the newer strains of SARS-CoV strains from the UK and South Africa.
There Are 3 Options for Antibodies Testing
At-Home Antibodies Self-Test Kit sent to Lab for processing
Attend a local Lab for blood draw with requisition
Rapid Antibodies Screen Self-Test Kit
Self-Test for COVID-19 Antibodies
Second Generation Antibodies Testing
Qualitative Detection of Antibodies Against COVID-19
The Elecsys® Anti-SARS-CoV-2 immunoassay is an in vitro test, using human serum and plasma drawn from a dry blood sample, to detect antibodies and determine the body’s immune reaction to SARS-CoV-2.
This serological assays can contribute to the identification of individuals exposed to the virus and assess the extent of exposure.
Elecsys® Anti-SARS-CoV-2 is an immunoassay for the in vitro qualitative detection of antibodies (including IgG) to SARS-CoV-2 in human serum and plasma.
Our immunometric assay testing for antibodies for COVID-19 is laboratory-based and can be collected in the safety and privacy of your home with a self-administered testing kit. This Roche diagnostics platform has a specificity greater than 99.8% and 100% sensitivity (14 days post-PCR confirmation), which means a false positive or false negative is now highly unlikely.
What makes all of our antibodies test distinctive is that you can perform it yourself at home, without the need to go to a laboratory, where the technician wears PPE and does a blood draw and sends one tube of your blood for processing.
Compared to a traditional blood draw sample, our Antibodies test for COVID-19 is collected in a dried blood format. This technique has been validated to be equal in sensitivity and specificity to a standard blood draw.
Once the collection device with a dried blood sample arrives at the CoreMedica Lab, the dried blood sample is reconstituted by adding a buffered solution. The sample is then processed, and results are generally available within 48 hours. The patient will be notified to review the report on a secure HIPPA compliant portal.
Self-Test Blood Spot Collection
Your kit will contain all the necessary supplies for self-collection in the comfort of your own home. The test only requires you to fill 3 circles with 2 drops of blood in each circle. You will collect your blood sample using the paper blot included in your kit.
Local Lab Blood Draw
Getting your antibodies at a Local lab requires:
Requisition from your physician
Pre-payment of $75
(not covered by Public Health Insurance)
Schedule an appointment at the local lab
NOTE: Available only in certain communities in Ontario and British Columbia. Contact your physician.
Rapid Antibodies Screen (Coming Soon)
Collecting of specimen
using a capillary tube
Apply the specimen
Apply the buffer
get result within 15 minutes
Interpretation of Test Results
“C” Control Line
“G” IgG Line
“M” IgM Line
Sensitivity – 93.90%
Specificity – 95.74%.
Interpretation of COVID-19 Antibodies Test Results
If You Test Positive/Reactive
A single positive result from either antibody, or both (IgG plus IgM), indicates you have likely been exposed to a coronavirus, even in the absence of symptoms from the infection, including if you have been recently vaccinated.
- Only a REPEAT POSTIVE test for IgG, over a longer period of time indicates likely immunity.
If You Test Negative/Non-Reactive
A negative result means that you have likely:
- not been infected with the SARS-CoV-2 virus, OR
- been infected with SARS-CoV-2 in the past, but their antibody levels were too low for the test to detect,
- not mounted an immune response yet to an infection or to a vaccination series against COVID-19
A single TNP result means that your sample could not be processed because the sample had insufficient serum. TNP stands for Test Not Performed.
Antibody testing performed < 3 weeks after onset of symptoms has reduced clinical sensitivity and may lead to false negative results.
Rare false positive results may be due to cross-reactivity with other coronaviruses.
Immunosuppressed individuals or those with mild disease may not produce measurable antibody levels.
Some studies indicate that a small percentage of people infected with SARS-CoV-2 (<4%) do not have detectable antibodies.