Choosing the "RIGHT" Test is Critical to Understand the Immune Response to SARS Cov-2 and COVID-19 Vaccination

Mumbai, April 19, 2021: Roche Diagnostics India launched its Quantitative antibody test- Elecsys Anti SARS CoV-2 S in January this year. The test since then has now been widely used in government and private hospitals and labs in various parts across the country. Roche Elecsys Anti SARS CoV-2 S test measures antibodies that could help detect a past natural infection or body’s immune response to the vaccine.

Roche Elecsys SARS CoV-2 S quantitative antibody test detects and quantifies antibodies in serum or plasma against the spike protein present on the surface of SARS CoV-2 virus. Spike protein is a common target for neutralizing antibodies. These type of antibodies prevent the virus from entering human cells thus protecting an individual. Hence, most COVID-19 vaccines contain the spike protein or at least a component of it so as to be able to produce an immune response in the form of antibodies and immune cells against it. The antibody immune response produced by vaccines can be quantified by measuring antibodies against the spike protein in a lab as done by the Roche Elecsys SARS CoV-2 S test.

As the neutralizing activity of antibodies is the closest link to potential protecting immunity, it becomes extremely relevant in the context of vaccination. The Roche Elecsys SARS CoV-2 S correlates extremely well with tests that detect such neutralization activity.

A quantitative antibody test reports amount or concentration of antibodies developed after vaccination or a\natural infection. On the other hand, a qualitative antibody test only gives a ‘Yes’ or ‘No’ answer though the results may be given in numbers. Thus, the qualitative test determines “if” and quantitative test answer the question “how much?” antibodies are produced. It is important to distinguish between the two while selecting an antibody test. 

Quantitative antibody tests should report the concentration in standard universally acceptable units rather than arbitrary units or an index.  This would allow a simple and uniform interpretation of test results. The units of the Elecsys Anti-SARS-CoV-2 S assay have an excellent correlation with and can be considered equivalent to the units of the WHO International Standard.

As new variants of SARS CoV-2 emerge, there is growing concern about their behavior and impact. It is essential that the chosen antibody test is able to detect antibodies developed against the variant virus, thus, indicating a past infection with SARS CoV-2.

Mr. Narendra Varde, MD, Roche Diagnostics India, “The Elecsys Anti-SARS CoV-2 S assay was introduced right in time along with the commencement of COVID vaccination drive in India. The test, with its excellent accuracy, correlation to neutralization assays and standard reporting, is apt to not only assess exposure to SARS CoV-2 but also characterize the vaccine-induced immune response. With this introduction, we continue to fulfil our commitment of bringing novel, high medical value innovations to the country.”


Mr. Arjun Ananth, CEO, Medall, “A quantitative test always gives the individual a sense on the level of immune response development post a vaccine. My recommendation would be to do this on a periodic basis. One prior to the shot, one 2-3 weeks post the second shot and perhaps one 6 months later to understand where one stands with respect to the level of antibodies, just given the knowledge on this virus is still evolving.”

Dr. Smita Juvvadi, Director Laboratory Medicine, Tenet Diagnostics, “Not all antibody tests are alike. The right antibody test to assess immune response after COVID-19 vaccination would be the one that quantifies antibodies and shows a close correlation with neutralization tests, indicating development of a relevant immune response. It is important that antibody concentration be reported in internationally acceptable units so that the interpretation becomes uniform.” 

Dr. S.P. Ganesan, MD, HiTech Diagnostics, “The SARS COV-2 virus causes mild to severe COVID by its S protein attaching to the host cell. Hence, most of the vaccines for COVID are developed to produce antibodies and immune cells to S protein to provide immunity. After vaccination, it may be ideal to measure the S-Protein antibodies specifically, to know whether a person has developed an immune response. Measurement of other COVID Antibodies will not be useful. Roche SARS CoV-2 antibody measures antibody to S-protein specifically and quantitatively. We have found it useful in assessing the immune response post-vaccination. Testing for other antibodies will give negative results, falsely indicating that the vaccine is not working.”

About Roche Diagnostics India

Roche Diagnostics India Pvt. Ltd. established in the year 2002 has offices located in Chennai, Delhi, Kolkata and Mumbai with over 400 employees. Our broad range of innovative diagnostic tests and systems play a pivotal role in the groundbreaking area of integrated healthcare solutions and cover early detection, targeted screening, evaluation and monitoring of disease. Roche Diagnostics India works with the objective of “Doing now what patients need next”, thus preparing for the nation’s future healthcare needs.


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