【Antibody Test】Understand COVID-19 Antibody Test

幼兒檢測 核酸檢測 INDICAID lab 港島中環檢測中心

Public demand for the 3rd dose of COVID vaccine and antibody test has been increasing in light of the occurrence of Omicron variant. What is antibody test? Why is it necessary even after COVID vaccination?

What are antibodies?

An antibody is a kind of protective protein produced by our immune system. Immune response is triggered when human body detects the presence of antigens which in turn starts producing antibodies. Therefore, antibodies are developed after SARS-CoV-2 infect our cells or vaccination.

Neutralizing antibody is a kind of protective antibody that binds to cell-free virus and prevent it from infecting cells by activating B cells and T cells. Immunoglobulin M (IgM) and Immunoglobulin G (IgG) are two common kinds of antibodies. Sufficient amount of antibodies can effectively lower the risk of severe disease and death; whereas a relatively low amount of antibodies implies a higher chance of infection.

When are antibodies produced?

Antibodies are normally produced by the immune system 7-10 days after viral infection. Once our body cells are infected, IgM antibodies will be developed first for a limited time, followed by IgG antibodies which can provide a relatively sustainable period of protection. Different immune responses and types of vaccine affect the amount of antibody produced after vaccination. Immune system starts producing antibodies 2 weeks after the 1st dose of vaccine, but only to generate a higher level of antibodies 2 weeks after the 2nd dose.

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What is serum antibody test? What does it tell us?

INDICAID labTM provides COVID-19 serum antibody testing service and can detect the level of IgG antibodies, which help neutralize the spike proteins of SARS-CoV-2, through collecting blood serum samples, and provide quantitative IgG antibodies data to determine if one was infected or vaccinated.

Understanding why antibodies cannot be developed after vaccination

Through providing quantitative antibodies data, COVID-19 serum antibody test from INDICAID labTM can determine if sufficient antibodies are produced after vaccination, which can further provide insight into the necessity to receive the 3rd dose of COVID vaccine.

INDICAID labTM COVID-19 Serum Antibody Test

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  • Test reagent (Abbott) authorised by the US FDA EUA, with sensitivity > 99%
  • HK Government recognised COVID-19 antibody test report

It is suggested to do a serum antibody test 2-4 weeks after receiving the 2nd dose of COVID vaccine. In case of a negative test result, you can consider doing another test after 2 weeks; if your test result is positive, you can test regularly according to individual inspection needs.

Learn more about serum antibody test