Antibody Test to detect COVID-19
An accurate, easy and simple blood test to know if you had a novel coronavirus infection recently
Antibody Test for COVID-19 checks for antibodies in your blood. A human body produces antibodies in blood when it fights an infectious diseases like COVID-19. Similar antibodies develop for instance, when you take a particular vaccine shot against some flue. This is exactly how you build immunity against a virus.
The Antibody Test for COVID-19 has been approved by the Indian Council of Medical Research (ICMR) via its advisory dated June 23, 2020
Who should be tested?
When you should get a COVID-19 antibody test?
Quick facts about Antibody Test for COVID-19
Analysis within 18 minutes and report usually on the same day
Sensitivity is 99.5% and Specificity is 99.8%
Blood sample is drawn from a vein in your arm and thereafter, the sample is tested in our lab
Very small quantity of blood sample is required
Samples can be collected from anywhere; at lab, in home, from office, from factory, etc.
Wear a face mask while giving your blood sample. Technician must also wear a face mask, face shield and sterile gloves
Is Antibody test for COVID-19 Accurate?
The antibody test for COVID-19 is intended as an aid in the determination of the immune reaction to SARS-CoV-2 and for sero-surveillance purpose. It is not meant for diagnosis of the disease.
RxDx is using ICMR approved Roche antibody kit called Elecsys® Anti-SARS-CoV-2. It is an immunoassay for the in vitro qualitative detection of antibodies (including IgG) to SARS-CoV-2 in human serum and plasma. The assay uses a recombinant protein representing the nucleocapsid (N) antigen for the determination of antibodies against SARS-CoV-2. Reproduced below is clinical sensitivity and specificity reports of Elecsys® Anti-SARS-CoV-2 – the kit being used at RxDx Bengaluru branches in Whitefield, Kadugodi, Siddapura, Bellandur and RxDx SAMANVAY branch in Malleswaram, North Bengaluru.
A total of 496 samples from 103 symptomatic patients with a PCR confirmed SARS-CoV-2 infection were tested with the Elecsys® Anti-SARS-CoV-2 assay. One or more consecutive specimens from these patients were collected after PCR confirmation at various time points. The results are produced below:
|Days post PCR confirmation||N||Sensitivity (95 % CI*)|
|0 – 6 days||161||60.2 % (52.3 – 60.8 %)|
|7 – 13 days||150||85.3 % (78.6 – 90.6 %)|
|≥14 days||185||99.5% (97 – 10|
A total of 10453 samples (from diagnostic routine, blood donors) obtained before December 2019 were tested with the Elecsys® Anti-SARS-CoV-2 assay.
|Cohort||N||Reactive||Specificity% (95 % CI)|
|Diagnostic routine||6305||12||99.81 % (99.67 – 99.90 %)|
|Blood donors||4148||9||99.78 % (99.59 – 99.90 %)|
|Overall||10453||21||99.8 % (99.69 – 99.88 %)|
How much does the COVID-19 Antibody Test Costs at RxDx?
This test costs ₹ 1,200 if samples are collected at RxDx Bengaluru branches in Whitefield, Kadugodi, Siddapura, Bellandur and RxDx SAMANVAY branch in Malleswaram, North Bengaluru. A home visit for the same will cost ₹ 500/- extra within 5 km radius of our branches.
RxDx is organizing camps all over Bengaluru and adjoining districts for Antibody Tests. Apartments, societies, offices, corporates, factories or industries can contact our helpline numbers or leave their details in the Request for Info Forms to receive a call back from our representatives. Camp costs are as follows:
|Antibody Tests for COVID-19 (CAMP MODE) in and around Bengaluru||Amount (₹)|
|For a batch of 1 to 5 persons||1,500|
|For a batch of 6 to 10 persons||1,400|
|For a batch of 11 to 24 persons||1,300|
|For a batch of 25 to 49 persons||1,200|
|For a batch of 50 and above persons||1,000|
Antibody Test vs Antigen Test
This newer COVID-19 test detects certain proteins that are part of the virus. Using a nasal or throat swab to get a fluid sample, antigen tests can produce results in minutes. Because these tests are faster and less expensive than molecular tests are, some experts consider antigen tests more practical to use for large numbers of people. A positive antigen test result is considered very accurate, but there’s an increased chance of false negative results — meaning it’s possible to be infected with the virus but have negative antigen test results. So antigen tests aren’t as sensitive as molecular tests are. Depending on the situation, the doctor may recommend a molecular test to confirm a negative antigen test result.
The body immune system produces antibodies — proteins that are critical for fighting and clearing out the virus. Depending on the method used for the antibody test, the COVID-19 antibodies are generally observed after a median of 10-13 days after symptom onset for IgM while about 12-14 days for IgG.
Whereas IgM seems to disappear around week, high IgG seropositivity is seen at that time. Levels and chronological order of IgM and IgG antibody appearance are highly variable, supporting detection of both antibodies simultaneously.
Few important points to consider about the Antibody Test results
What, if you test positive for COVID-19 antibodies?
- Don’t let your guard down if your antibodies test results are positive. Continue to protect yourself and others since you could get infected with the virus again. Scientists are working to understand this. If you work in a job where you wear personal protective equipment (PPE), continue wearing PPE
- It is quite possible that some antibody tests can mistake IgM and IgG antibodies from other coronaviruses, such as the common cold strains, for SARS-CoV-2 antibodies
- If your antibody test result for SARS-CoV-2 is positive, it probably means you were infected by the virus recently. However, it is also possible to get a “false positive” if you have antibodies but had a different kind of coronavirus
- A positive antibody result might mean you have some immunity to the coronavirus. But it certainly is not your immunity passport. In fact, it’s premature to know how strong your antibodies are and how long it can give you the protection against COVID-19
- You test results for antibodies may turn out to be positive even if you have never had symptoms of COVID-19. This usually happen if you had an infection without symptoms, which is called an asymptomatic infection.
What, if you test negative for COVID-19 antibodies
- A negative result might indicate that either you have not come into contact with the novel corona virus or you have not had it long enough to make antibodies against COVID-19. You could also have been exposed and not have antibodies. This is called a false negative
How do we get antibodies in our body?
Antigens trigger the production of antibodies, also called immunoglobulins. Five types of immunoglobulins are produced in our body for different purposes. IgM and IgG are the major players in detection of COVID infection.
How antibody test is done for COVID-19?
Blood sample is drawn from a vein in your arm and thereafter, the sample is tested in a lab using advanced machines. It takes just 18 minutes for the test to be performed. Report is usually generated on the same day.
How an antibody test works?
An antibody test fast checks for antibodies in your blood. Your body makes antibodies when you get an infection. They help fight the infection. If you have coronavirus antibodies in your blood, it’s likely you’ve had the virus before. It’s not known if having antibodies stops you getting the virus again
Why Antibody test is important for COVID-19?
This test offers a way for a person to know if they have had COVID-19 in the recent past.