Page Banner
COVID-19 Antibody Testing
COVID-19 Antibody Testing

COVID-19 Antibody Blood Test

Find out if you’ve had COVID-19 through an Antibody test.
This blood test detects prior infection, even if you never experienced symptoms.

How is the test performed?

Blood sample.

Find out which COVID-19 test is right for you

Coronavirus Disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). COVID-19 was identified in December 2019 and declared a global pandemic by the World Health Organization in March 2020.

Type and severity of symptoms of an active COVID-19 infection vary greatly between individuals depending on the age, gender, and underlying medical conditions.  The most commonly reported ones include fever, loss of smell, coughing, sore throat, shortness of breath or difficulty breathing, feeling weak or lethargic, chills, muscle pain, light-headedness or dizziness, headache, vomiting or diarrhea, slurred speech, and/or seizures.  Less common symptoms include stuffy nose, conjunctivitis (pink eye), dizziness, confusion, abdominal pain, and skin rashes or discoloration of fingers or toes.  Many studies show that a percentage of infected individuals may not exhibit any symptoms at all.

 

Disclaimer

As the COVID-19 pandemic evolves, test standards and requirements continue to evolve.  LifeLabs will work to maintain testing which meets these evolving standards. However, it is not possible to predict every change which might occur, or the timing of any change.  Health care providers and their patients should recognize that this risk is outside of LifeLabs’ control.

Antibodies are proteins generated by the immune response to infections.  They have many anti-viral functions, such as preventing viral entry into host cells.  The antibodies can be produced even if a person has few or no symptoms during the infection.

COVID-19 antibody test detects antibodies reactive to SARS-CoV-2 viral proteins.  This test can be used to assess recent or previous infection with SARS-CoV-2.  This test is most accurate when sample is collected 3-4 weeks after onset of symptoms or 3-4 weeks after exposure. 

At this time, it is not known if the presence of antibodies to COVID-19 means you are immune to the virus and protected from re-infection.  Importantly, it is not known how long antibody response to COVID-19 virus lasts. Based on current studies, antibodies to COVID-19 virus can be detected up to 4 months post-exposure, but levels vary depending on individual immune response as well as disease severity, with levels higher in severe and lower in milder/asymptomatic cases.

LifeLabs offers two COVID-19 tests.

The molecular test (e.g. polymerase chain reaction (PCR)) detects SARS-CoV-2 genetic material and is used to diagnose an active COVID-19 infection. A sample type used in molecular testing is a nasopharyngeal (NP) swab. 

The COVID-19 antibody test is a blood test to detect antibodies to the virus.  Results of the test show whether you had a recent or prior COVID-19 infection.  The antibody test is not to be used for diagnosis of active COVID-19 infection.

VIEW INFOGRAPHIC

If you suspect that you previously had COVID-19, even if you never showed symptoms or signs of illness, your healthcare provider can order an antibody test to assess recent or prior infection.   Antibody responses to the virus take some time to develop and vary between individuals.  For most accurate results (results with highest sensitivity) it is recommended the antibody test is ordered 3-4 weeks post-onset of symptoms or post-exposure. However, based on current studies, antibodies to COVID-19 virus can be detected up to 4 months post-exposure.

To get tested for COVID-19 antibodies, talk to your healthcare provider and have them provide you a signed test requisition form. If you are consulting your physician via phone / virtually, you can request them to email you a PDF of the requisition form. You can then visit a LifeLabs patient service centre (PSC) to get your blood sample collected and pay for the COVID-19 antibody test. Appointments are recommended, although walk-ins are welcome.

You also have the option to pre-pay for this test online by clicking the red ‘How to Order’ button on top of this page. We will email you an electronic requisition that is pre-filled with your information. You must get this e-requisition signed by your healthcare provider, prior to visiting a LifeLabs PSC to get your blood sample collected.

Results will be available within 1-2 business days from sample collection. Your results will be sent to your ordering physician.

*LifeLabs normally will be able to report a test result within 1-2 business days.  However, events outside of LifeLabs’ control may affect LifeLabs’ ability to meet this turnaround time.  The customer accepts the risk of such events.  LifeLabs will not be liable to the customer for such events.  

  • The COVID-19 antibody test is not to be used for diagnosis of an active COVID-19 infection. The molecular test is used to diagnose infection.
  • The result of COVID-19 antibody test cannot tell you whether or not you have a protective immunity against the virus.
  • The result of COVID-19 antibody tests cannot tell you whether or not you are infectious (actively shedding virus).

Note that the results may be reported as ‘Reactive’ (i.e. positive for antibodies) or ‘Non-reactive’ (i.e. negative for antibodies). A detailed explanation of what these terms mean has been provided below:

A negative COVID-19 antibody test result means that antibodies to SARS-CoV-2 were not detected in your blood sample. This could mean that:

  • You have not been infected with SARS-CoV-2, or
  • You have been infected with SARS-CoV-2 in the past, but your antibody levels were too low for the test to detect, or
  • You have been infected with SARS-CoV-2, but there has not been enough time for antibodies to develop (antibody response varies from person-to-person and can take up to 3-4 weeks post-onset of symptoms or post-exposure to be reliably detectable by antibody assays).

Some studies indicate that a small percentage of people infected with SARS-CoV-2 do not have detectible antibodies (< 4%). Immunocompromised individuals may have low antibody responses to SARS-CoV-2

A positive antibody test result means that antibodies were detected in your blood sample. This typically indicates that:

  • You have been infected by SARS-CoV-2 virus in the recent past.
  • In rare instances, falsely positive results may be caused by cross-reactivity of the test with other viruses
  • The positive result does NOT infer immunity or protection from re-infection.

Please discuss both positive and negative results with your physician. 

COVID-19 antibody test is a blood test that detects antibodies reactive to SARS-CoV-2 viral proteins, most commonly viral nucleocapsid (N) or spike (S) proteins.  This test can be used to assess recent or previous infection with SARS-CoV-2.  Unlike a molecular COVID-19 test, the antibody test is not used in diagnosis of active infection.

The antibody test is most accurate (has highest clinical sensitivity) when a blood sample is collected 3-4 weeks after onset of symptoms or 3-4 weeks after exposure. 

At this time, it is not known if the presence of antibodies to COVID-19 means an individual is immune to the virus and protected from re-infection.  Importantly, it is not known how long antibody response to COVID-19 virus lasts.   Based on current studies, antibodies to COVID-19 virus can be detected up to 4 months post-exposure, but levels vary between individuals depending on disease severity, with levels higher in severe and lower in milder/asymptomatic cases. Antibody levels can also be lower in immunocompromised individuals. 

 

Disclaimer

As the COVID-19 pandemic evolves, test standards and requirements continue to evolve.  LifeLabs will work to maintain testing which meets these evolving standards. However, it is not possible to predict every change which might occur, or the timing of any change.  Health care providers and their patients should recognize that this risk is outside of LifeLabs’ control.  

 The Roche Elecsys Anti-SARS-CoV-2 Total Antibody is a qualitative immunoassay which detects antibodies (IgG, IgM, and IgA) to the nucleocapsid (N) antigen of the SARS-CoV-2 virus. This assay detects high affinity antibodies, therefore favoring IgG, and does not differentiate between antibody type. Internal validations showed the test has a sensitivity of 96% to detect COVID-19 antibodies > 3 weeks post-symptom onset and specificity >99%.  These performance characteristics meet Health Canada requirements for COVID-19 antibody tests.

The predictive value of the test is strongly dependent on prevalence of disease. For example, for a disease prevalence of 1 %, the COVID-19 antibody test has a positive predictive value of 65 % and a negative predictive value of 99.9 %. Whereas, for a disease prevalence of 10 %, the test has a positive predictive value of 95 % and a negative predictive value of 99.1 %. Thus, clinical correlation is strongly recommended for test ordering and interpretation.

You may consider ordering COVID-19 antibody testing in the following circumstances*:

  • If a patient has signs and symptoms of COVID-19 but has repeatedly tested negative for COVID-19 by a molecular test
  • In a diagnostic workup of patients who display long-term symptoms of COVID-19 (persisting for a number of months) but who have never been diagnosed by a molecular test (e.g. due to lack of eligibility for testing).

*Please note that these are suggestions only, as evidence for the diagnostic use of COVID-19 serology test is still evolving.

Additional potential non-diagnostic applications for COVID-19 antibody testing include:

  • Individual risk assessment to ascertain recent or previous infection
  • Outbreak investigations (after molecular testing)
  • Clearance for travel (after molecular testing)
  • Clinical trials
  • Laboratory testing for insurance companies

The results may be reported as ‘Reactive’ (i.e. positive for antibodies) or ‘Non-reactive’ (i.e. negative for antibodies). A ‘Reactive’ (positive) result indicates that the patient’s sample has antibodies that are reactive to the SARS-CoV-2 virus, which is a very strong indication of prior infection. A ‘Non-reactive’ (negative) result means that detectable levels of antibodies were not found in the sample. Further explanation has been provided below:

A negative COVID-19 antibody test result means that antibodies to SARS-CoV-2 were not detected in a patient’s blood sample. This could mean that:

  • A patient has not been infected with SARS-CoV-2, or
  • A patient has been infected with SARS-CoV-2 in the past, but their antibody levels were too low for the test to detect, or
  • A patient has been infected with SARS-CoV-2, but there has not been enough time for antibodies to develop (antibody response varies from person-to-person and can take up to 3-4 weeks post-onset of symptoms or post-exposure to be reliably detectable by antibody assays).

A positive antibody test result means that antibodies were detected in your patient’s blood sample. This typically indicates that:

  • A patient has been infected/exposed to the by SARS-CoV-2 virus in the recent past.
  • In rare instances, falsely positive results may be caused by cross-reactivity of the test with other viruses

The following limitations of COVID-19 antibody testing should be considered:

  • Positive antibody (serology) test results do not infer immunity and protection from re-infection
  • Serology results should not be used to exclude active infection
  • 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.

Antibody testing must be ordered by a healthcare provider. Patients can make an appointment at a LifeLabs patient service center for this test.

Healthcare providers can order the COVID-19 antibodies test for their patients in following ways:

Using the standard laboratory requisitions:

  1. In Ontario, by writing ‘COVID-19 Antibodies’ in the ‘Other Tests’ section of the standard MOH-issued OHIP requisition. Please check the box for ‘Uninsured / Third party’ when filling the requisition.
  2. In British Columbia, by writing ‘COVID-19 Antibodies’ in the ‘Other Tests’ section of the LifeLabs standard laboratory requisition for your specific region. Please check the box for Bill-to ‘Patient’ when filling the requisition.
  3. Your patients have the option to pre-pay for the test online on LifeLabs.com, which will allow us to email them a requisition pre-filled with their details. You must sign this requisition before it can be used by LifeLabs to do the blood draw

An appointment at a LifeLabs Patient Service Centre is recommended for this blood draw although, walk-ins are also welcome.

LifeLabs offers COVID-19 antibody testing as a patient-paid service for individuals who fall outside the coverage criteria set by public health. Physicians are advised that billing the British Columbia Medical Services Plan (in BC) or the Ontario Health Insurance Plan (in ON) for ordering this service through LifeLabs is not authorized.

The test costs $75.

Results will be available to the ordering physician within 1-2 business days from the date of specimen pickup.

*LifeLabs normally will be able to report a test result within 1-2 business days.  However, events outside of LifeLabs’ control may affect LifeLabs’ ability to meet this turnaround time.  The customer accepts the risk of such events.  LifeLabs will not be liable to the customer for such events.  

The LifeLabs COVID-19 antibody test may be scheduled directly by the patient at any of our Patient Service Centres offering this service. They must have a requisition form completed by a physician or healthcare provider.

Find the nearest LifeLabs Location 

Book an Appointment

Request more information