【Antibody Test】Get Tested Before Booster Shot?
The government announced that eligible persons under certain groups can receive a third dose of COVID-19 vaccine free of charge starting from November 11 2021 to enhance antibody level.
Should I get an antibody test before receiving my third dose of vaccine?
According to the government, individuals who are classified as priority groups for receiving a third dose include:
| Priority Group | When to receive 3rd dose? |
|---|---|
| Immunocompromised individuals | At least 4 weeks from 2nd dose |
| Persons with a high risk of infection* (only for individuals aged 18 or above if receiving 2 doses of BioNTech vaccine) | At least 6 months from 2nd dose |
*including elderly aged 60 or above; healthcare workers; persons with chronic illnesses; and workers at increased risk for COVID-19 exposure and transmission because of occupational setting
Since individual immune response after vaccination differs, it is recommended to take an antibody test before receiving third dose of vaccine. Should the antibody test result be negative, it implies a relatively low antibody level. While a positive result indicates a higher antibody level, taking antibody tests regularly can still help determine if there are sufficient antibodies before deciding on the third dose.
Who else should also get an antibody test?
Different immune response affects the amount of antibody produced from vaccination. Therefore, the immune system of some individuals who are fully recovered from COVID-19 or received second dose of vaccine may not induce sufficient antibody response due to the following reasons:
- Impaired immune system (e.g. elderly, those receiving chemotherapy or have unstable blood sugar level)
- Immune system cannot identify coronavirus
- Declining number of antibodies (antibody level drops 6 months after vaccination)
Studies found that more than 30% of COVID-19 recovered patients cannot develop sufficient antibodies^, whereas antibodies generated after infection can only last for 5-6 months. Therefore, it is recommended to get antibody tests regularly to check your antibody level status.
INDICAID labTM COVID-19 Serum Antibody Test
- Test reagent (Abbott) authorised by the US FDA EUA, with sensitivity > 99%
- HK Government recognised COVID-19 antibody test report
When should I get an antibody test?
Immune system starts producing antibodies 2 weeks after the first dose of vaccine, but only to generate a higher level of antibodies 2 weeks after the second dose. Therefore, it is recommended to get an antibody test 2-4 weeks after the second dose:
| Antibody Test Result | Suggestion |
|---|---|
| Negative | Can test again in 2 weeks |
| Positive | Test regularly according to individual inspection needs* *positive result does not guarantee complete immunity from coronavirus, maintaining good personal hygiene and avoiding crowded events are still crucial to reducing the risk of infection |
Learn more about serum antibody test
^36% of Those Who Had Covid-19 Didn’t Develop Antibodies, Study Says (Lee, 2021)
