What is the Vector COVID-19 Antibodies (Serology) test?

Antibodies are a protective protein produced by the immune system in response to the presence of a foreign substance, called an antigen.  As antibodies circulate, they attack and neutralize antigens that are identical to the one that triggered the immune response.  Antibodies can be produced even if a person has few or no symptoms during the infection.

The COVID-19 antibody test currently offered by Vector Health can be used to detect anti-viral antibodies following vaccination and prior exposure/infection to the SARS-CoV-2 virus

The test detects antibodies against the nucleocapsid (N) protein of the SARS-CoV-2 virus, and spike (S) protein which are elicited antibodies of the virus particle.

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. 

• The N-Protein Antibodies Reactivity Index is an indication of your immune response to a recent exposure to COVID-19. These antibody levels typically decrease over time and could also provide relevant information related to an exposure to COVID-19 that you may not have been aware of.

• The S-Protein Antibodies Reactivity Index is an indication of your immune response to an exposure to COVID-19 and/or your immune response to your COVID-19 vaccination.  

When to consider COVID-19 Antibody testing?

If you suspect that you previously had COVID-19, even if you never showed symptoms or signs of illness, you may wish to consider the Vector Health Antibodies test to assess recent or prior infection.   Antibody responses to the virus take time to develop and vary between individuals.  For most accurate results (results with highest sensitivity) it is recommended the antibody test is conducted 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.

What do the numbers mean?

• If levels are below 0.9, No detectable antibodies.
• If levels are between 0.9-1.1, Antibody levels are indeterminate.
• Between 1.1 and 2.5, Reactivity Index is low – Low detectability of antibodies
• Anything over 2.5, Reactivity Index is high – High detectability of antibodies

Levels between 2.5 and 20 do not represent ‘protection level’.  Numbers are based on personal characteristics and are a point in time measure.  

The Vector Health Antibodies test is not to be used for diagnosis of an active COVID-19 infection. A 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.

I had my 2nd vaccine over 7 months ago and my S-protein levels are still high

If your results still show an elevated S-Protein Reactivity Index months after COVID-19 vaccination, it is an indication that you have successfully generated an immune response through vaccination and S-Protein specific antibodies have been created to possibly help protect you from severe symptoms and outcomes from subsequent exposure to COVID-19. However, it is always recommended to continue to follow Public Health guidelines with regards to hand washing, mask wearing and physical distancing.

Reactivity Index Explained

A negative reactivity index COVID-19 antibody test means that antibodies to SARS-CoV-2 were not detected in your blood sample.

This could mean that:

N-Antibodies

• 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).

S-Antibodies

• You have not developed antibodies from a vaccination (if vaccinated), or
• You have been infected with SARS-CoV-2 in the past, but your antibody levels were too low for the test to detect.

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 reactivity index COVID-19 antibody test means that antibodies were detected in your blood sample.

This typically indicates that:

N-Antibodies

• You have developed and immune response to a recent exposure to COVID-19.  These antibody levels typically decrease over time and could also provide relevant information related to an exposure to COVID-19 that you may not have been aware of.

S-Antibodies

• You have developed an immune response antibodies from a vaccination (if vaccinated), or
• You have developed an immune response through direct exposure to SARS-CoV2.