Serological COVID-19 spike protein antibody testing can identify individuals who have been exposed to the SARS-CoV-2 virus, regardless of symptom presentation, and quantify their personal immune response. We offer two testing options for the S-RBD antibody (spike protein receptor binding domain), the target of current COVID-19 vaccines due to the S-RBD antibodies ability to block the passage of COVID-19 to cells. The tests are optimized for pre and post vaccination testing, to deliver the information your patients need based on their individual circumstances.

When combined into a pre/post vaccination assessment, the COVID-19 Immune Response Panel and the COVID-19 Vaccine Response Screen provide clarity into not only when an individual should receive a vaccine, but the effectiveness of their body’s immune response to the inoculation.

What are S-RBD antibodies?

S-RBD stands for “spike protein receptor-binding domain.” The COVID-19 S-RBD binds to the ACE2 receptor and allows the virus access to the body’s cells. Higher levels of S-RBD antibodies have been shown to block or “neutralize” the COVID-19 virus from getting into cells and causing infection.

Typically, Individuals who have recovered from a COVID-19 viral infection usually have high levels of antibodies specific to S-RBD. The “neutralizing” ability of S-RBD antibodies is why all three of the Emergency Use Authorized (EUA) vaccines target the S-RBD, although they use different methods for getting the S-RBD protein information into the body.

Why measure S-RBD antibodies separately?

While human studies indicate that spike protein and nucleocapsid protein antibodies elevate in response to COVID-19 virus exposure, these antibodies are not as specific as the S-RBD antibodies for preventing COVID-19 infection (or re-infection) or for confirming post-vaccination status. After the virus infects the human body, it creates a large quantity of both “neutralizing” antibodies such as S-RBD and many nonspecific endogenous antibodies.

Although a general trend of post-infection increases in spike and nucleocapsid antibodies in association with increased S-RBD antibodies has been observed, measurement of the generalized antibodies is not always predictive of S-RBD status, particularly when the only stimulus is an S-RBD vaccine:

The COVID-19 Vaccine Response Screen measures only the antibody response to the S-RBD protein. Once the baseline immune response has been established, this test can be used post-vaccination to evaluate immune status. The average time for seroconversion has been estimated at 2-3 weeks. However, the strongest antibody responses will likely be seen after the second vaccine dose 6-8 weeks after the first inoculation.