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FAQ: SARS-CoV-2 Spike Protein Antibodies Testing


FAQ: SARS-CoV-2 Spike Protein Antibodies Testing

Who is this examination for?
People who have been vaccinated against COVID-19 or has been infected and recovered who want to know if they have developed antibodies to Spike (S) protein.

If my test result detects antibodies, does that mean I will not be infected?
Although there are detectable antibodies, this does not mean that infection can be 100% prevented. Breakthrough infection is known to occur, but it is usually milder. Mask-wearing, frequent hand washing and social distancing are still recommended. Avoid activities that increase the risk of infection and strictly adhere to the government's up to date guidelines in effect during the pandemic. Guidelines may change based on future dynamic of the pandemic, e.g., the number of fully vaccinated people and new daily cases.

Benefits of the test
If the test does not detect antibodies, it means the body did not respond to the vaccination. Consider revaccination with a different vaccine technology.

How long should I wait after vaccination to get the test?

  • For Sinovac/Sinopharm vaccine: 4-6 weeks after getting two doses of vaccination.
  • For AstraZeneca vaccine: 4-6 weeks after the first dose of vaccination or 4-6 weeks after the second dose.
  • After infection 4-6 weeks after recovery from the infection.

Is this test certified?
This test uses reagents that have been registered and certified by the Food and Drug Administration (FDA).

What are the limitations of the test and caveat for interpreting the test results?

  • The protective level of antibodies against COVID-19 has not yet been determined because it is a very new test, not much data is available and further studies are required.
  • It is not possible to compare the test results among different test methodologies from different companies because the reference values and units are not the same.

Reporting for COVID-19 Antibody Tests

  • SARS-CoV-2 Spike Antibody
    • Positive Result: Antibodies to the SARS-CoV-2 spike glycoprotein detected. These results suggest recent or prior SARS-CoV-2 infection or vaccination. Antibody levels greater than or equal to 0.80 U/mL are considered positive by this assay. No minimum antibody level or threshold has been established to indicate long-term protective immunity against re-infection.
    • Nagative Result:No antibodies to SARS-CoV-2 spike glycoprotein detected. Negative results may occur in serum collected too soon following infection or vaccination, in immunosuppressed patients, or in patients with mild or asymptomatic infection. This test does not rule out active or recent COVID-19 infection or vaccination. Follow up testing with a molecular test for SARS-CoV-2 is recommended in symptomatic patients.
  • SARS-CoV-2 Spike Ab (Quantitative): Number result
    • >/= 0.80 U/mL: Positive
    • <0.80 U/mL: Negative

* It is yet undetermined what Antibody level is correlated to immunity against developing the COVID-19 infection.


Published: 30 Oct 2022