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Sanjeev Kumar Patro

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  • IgG: Known as marathoner antibody, they confer sustained immunity. These antibodies are detected in blood plasma.
  • IgM: Termed as the first line of human defence, the body produces first when fighting an infection. These antibodies are detected in blood plasma.
  • IgA: This antibody protects against infection on the body’s mucosal surfaces, such as those found in the respiratory and gastrointestinal tracts, and are found in high levels in tears, mucus, and other bodily secretions.

With the Odisha government having pushed the unlock button from July 1, and people in the State getting adapted to business as usual, a heightened concern did nag them, especially those infected by the virus or those who took a shot in their arms - Am I protected from Covid-19? The question bothering them is: If protected then how long?

In order to know their protection status, they need to take a specific test at an appropriate time, say doctors. "The antibody test need to be taken after 14-days post recovering from Covid-19 or after vaccination," explains Dr Biswanath Padhi, Senior Medicine Specialist, Khordha DHH.

What Is Antibody Test?

This test look for antibodies in your blood that fight the virus that causes COVID-19. These antibodies are proteins created by your immune system that help one fight off the infections. They are made after having been infected or vaccinated against an infection.

Termed as the soldiers of human body, antibodies fight off infections and can protect one from getting that infection for some period of time afterward. How long this protection lasts is different for each disease and each person.­

"As per studies, the Spike-protein antibodies (Immunoglobulin G or IgG) may last in human body for at least 6-months against the Covid-19 virus. Since this is a new disease, studies are underway to ascertain how long the neutralising antibodies last in human body," observed Dr Padhi.

Therefore, in order to ascertain one's protection status, they must go for the right antibody test - the IgG, said Dr Padhi.

Studies Corroborate Doc's View

As per a study published in bioRxiv by the researchers at Sinopharm Wuhan Plasma-derived Biotherapies Co., Ltd and Wuhan Institute of Biological Products Co. Ltd, find that the RBD-IgG displayed a downward, with the titre starting to stabilise after nine months and getting dropped by 68 per cent compared with first month.

Simply put, the study confirms that specific antibodies generated in the body decreases in quantity over the time. As per the study, the quantity was down by 68 per cent in the 9th month.

The studies published by National Institute of Health, USA, the IgG antibodies have been detected in the body even after 4-months. The IgM and IgA antibodies, however, vanish after 2-month.

Another US study finds that the B and T-cells that produce the antibodies keep the Covid-19 antigen in their memory even after 4-months, despite a drop in IgG quantity. The study, therefore, observed the development very promising as it could prove game-changer in the fight against Covid-19.

Types Of Antibody Detected in Covid

As per NIH, three types of antibodies are detected in patients recovered from Covid. They are; IgG, IgM and IgA.

IgG: Known as marathoner antibody, they confer sustained immunity. These antibodies are detected in blood plasma.

IgM: Termed as the first line of human defence, the body produces first when fighting an infection. These antibodies are detected in blood plasma.

IgA: This antibody protects against infection on the body’s mucosal surfaces, such as those found in the respiratory and gastrointestinal tracts, and are found in high levels in tears, mucus, and other bodily secretions.

Know Your Antibody Range

If the antibody test results positive, then you have either exposed to Covid-19 infection or the vaccines have triggered such a response. The next step is take a look at quantity. Details follow.

Normal Ranges Adult:

  • IgG 6.0 - 16.0g/L
  • IgA 0.8 - 3.0g/L
  • IgM 0.4 - 2.5g/L

As per Dr Padhi, if the antibody quantity exceeds the normal range then one should not worry. Rather, they need to feel happy that they have higher antibody range.

But, if the antibody detected fall below the normal range, then it will be cause of worry. This shows that body's immune system is not functioning optimally.

However, Dr Padhi cautioned, "Don't over read the IgG antibody positive test. Precaution is must. No study has confirmed that re-infection is impsossible." 

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