Most of us are familiar with Covid-19 RT-PCR tests. What about Covid-19 Antibody Tests? Lately, some laboratories are offering Covid-19 Antibody Test Packages. Do you know which different types of antibody tests are available in Malaysia? Let us break it down for you!
IgG & IgM Antibodies Test
Generally, the most common antibodies targeted in Covid-19 serology tests include IgG and IgM antibodies. IgM is usually the first antibody produced by the immune system when a virus attacks. At the same time, IgG may be detected as well. IgM is most useful for determining RECENT infection only as it usually becomes undetectable weeks to months following an infection. On the other hand, IgG may remain detectable for a longer period of time. The Covid-19 Antibody Test package usually includes detection of both IgM and IgG antibodies to predict the course or phrases of the infection and reduces the false-negative rate.
Samples Required: Venous Blood
Results Within: 3-5 hours
Interpretation of the Results:
IgM Detected=> Recently exposed/infected with Covid-19
IgM Not Detected => Not recently exposed/infected with Covid-19
IgG Detected => Indicative of past Covid-19 infection
Note that: The antibody test is NOT for detection of currently ACTIVE Covid-19 infection and should not be used as the sole criteria for diagnosis of Covid-19. Also, this test is unable to tell whether the antibodies detected are capable of fighting the Covid-19 virus. (Confused? No worries! Continue reading for further understanding.)
Neutralising Antibody (NAb) Test
When a person HAD a past covid-19 infection, there would be antibodies produced in the body but not all of them could bind to the viral antigens.
Neutralising antibodies (Nab) are a subset of antibodies that have the ability to block viral entry into host cells and neutralise the function of the Covid-19 virus. These antibodies are primarily of the IgG isotype.
This test assesses the effectiveness of your vaccine. A positive result indicates your immune system is prepared against the virus. The higher the level of Nab detected, the stronger is your immunity against Covid-19 virus.
This test caters to those who:
- Taken full doses of the Covid-19 vaccine for at least TWO WEEKS
- Recovered from a Covid-19 infection for at least TWO WEEKS
Samples Required: Blood
Results Within: 6 hours
Note that: An allowance of minimum of TWO WEEKS after completion of Covid-19 doses or after recovering from the infection could be an accurate way to check whether you have developed immunity towards the infection.
Type of Test |
IgG & IgM Antibodies Test
|
Neutralising Antibody (NAb) Test
|
Purpose |
To identify those suspected of having PREVIOUS Covid-19 infection. |
To check the functioning antibodies level in those post-vaccination individuals. |
Sample |
Venous Blood |
Blood |
Result Interpretation |
IgM Detected=> Recently exposed/infected with Covid-19 IgM Not Detected => Not recently exposed/infected with Covid-19 IgG Detected => Indicative of past Covid-19 infection
|
The higher the level of Nab detected, the stronger is your immunity against the Covid-19 virus. |
Results Within |
3-5 hours |
6 hours |
Suitable For |
Those who suspect themselves of having previous Covid-19 infection but were asymptomatic. |
Those who have taken full doses of the Covid-19 vaccine for at least TWO WEEKS or those who have recovered from a Covid-19 infection for at least TWO WEEKS.
|
Take-Home Message:
In short, antibody IgG & IgM test is recommended for those suspected of having PREVIOUS Covid-19 infection whereas NAb test is recommended for post-vaccination individuals to check their functioning antibodies level.
Prepared by: Chew Ee Wei, a HTM Pharmacist.
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