COVID-19 IgG Antibody

OVERVIEW

What is Covid-19?

Coronavirus or commonly called Covid-19 (named after its deadly strain reported in 2019) has taken the world by storm. The Covid-19 strain belongs to family of coronaviruses which are known to cause respiratory illness in humans. This newly discovered covid-19 virus is so contagious that it is rapidly transmitted from person to person through droplets of saliva or discharge from nose when someone infected sneezes or coughs. Ever since its outbreak worldwide, it has become necessary for people to practice respiratory etiquettes like coughing into flexed elbow, avoid shaking hands, sanitization & to wear a mask.  

What is Covid-19 IgG antibody test?

As the name suggest, this test is done in case of checking for covid-19 antibodies in an individual. Antibody testing will not check virus itself rather it checks if body’s immune system has responded well against an infection. Covid-19 antibody test is also known as serologic tests which detect presence of antibodies in blood serum within days to weeks of acute infection. The Covid-19 IgG antibody test identify resolving or past SARS-CoV2 (Severe acute respiratory syndrome coronavirus 2) infection and not meant for diagnosis of the acute SARS-CoV2 infection.

Why is Covid-19 IgG antibody test done?

The antibody testing or serologic testing is not a replacement of virologic testing. And therefore, this test shouldn’t be used for diagnosis i.e. for establishing the absence or presence of acute SARS-CoV2 infection. Rather this test helps:

• It works as a support after viral detection methods have been done, and result came positive, then this test supports in diagnosis of Covid-19 illness
• A positive antibody test will help support diagnosis of a person presenting with complications of Covid-19 like multisystem inflammatory syndrome & other post-acute sequelae (condition which is consequence of a previous disease or injury) of covid-19.
• Moreover, the Immunoglobulin G (IgG) which stay in body for months to years, when IgG test comes positive, it helps reflect upon previous SARS-Cov2 infection.
• The test used in occupational, clinical & public health purposes, and helps differentiate between natural infection and vaccination.
• It is also helpful in case of asymptomatic individuals who have been infected with Covid-19 in the past and don’t know, as this gives experts a better idea of how common the virus is in a population.
• The individuals who have antibodies in their blood against Covid-19 become eligible for going back to work or a normal life quicker.

• Firstly, a blood sample is taken by inserting needle in vein in arm
• The sample collected in air-tight vial or test tube is sent to the laboratory
• The technician isolates serum or plasma from the blood sample and undergoes suitable IgG antibody test for checking covid-19 antibodies in blood. If test comes positive, it helps detect past interaction with covid-19 in an individual.

1. How soon will antibodies be produced in a Covid-19 infected patient?

Depending upon how strong a person’s immune system is, with several other factors like age, severity of disease & nutritional status. It takes about 2 weeks for a person’s body to start producing antibodies after they’ve had confirmed diagnosis by molecular testing (RT-PCR etc.)

2. What is the purpose of Covid-19 rapid antigen test?

This test is commonly being used to diagnose Covid-19 infection, by looking for proteins made by SARS-CoV-2 virus which is responsible for Covid-19.

3. Can coronavirus be detected in blood and stool?

Yes, covid-19 can be detected in stool & blood, as had the coronaviruses accountable for SARS & MERS

4. What is coronavirus disease incubation period?

The time b/w exposure to virus and just when symptoms start appearing is 5 to 6 days average. Although it can be 14 days too. So, person should stay quarantined in a place for 14 days from last exposure to confirmed case

5. Can Covid-19 occur even after second vaccine?

It takes about 2 weeks for body to build immunity after vaccination. Therefore, it is possible that a person might get infected before or just after covid-19 vaccination. And get sick as vaccine didn’t have enough time to provide protection.

INTERPRETATION OF THE RESULTS:

The SARS-COV-2 IgG test is both qualitative and semi-quantitative antibody test which helps clinicians in detecting immunoglobulin G levels in patient’s blood sample and access the relative changes over time. The test results can be interpreted as:

• Positive: Patient has high likelihood of prior/past covid-19 infection. And you have antibodies to protect against future infection. However, it is unknown as to how strong can the immunity be or how long will it last
• Negative: Patient has not had any covid-19 infection in the past. And is prone to encounter it in the future.
• Equivocal: The test is not clear as to whether it is positive or negative. A repeat test is recommended.

This test is required when one thinks they might have come into contact with coronavirus. Or it is done after you’ve tested positive for Covid-19 & have fully recovered. Antibody testing is a good means of detecting if a person has encountered the virus in the past or not. It also helps in identification of potential donors of convalescent plasma (blood from people who’ve recovered from the disease), verify effectiveness of vaccines, & to establish prevalence of disease in populations.