A lot of people are signing up for lucrative tests as part of the ‘COVID preventive screening’ packages. Some corporates are also asking employees to get tests done before they come back to the office. Dr Shivani Sharma, Vice President, Pathology Services, CORE Diagnostics, mentions that there is a spike in the number of enquiries for these tests. “A lot of people are signing up for Anti SARS-CoV-2 IgG Test and Total Antibody test (IgG & IgM) priced at INR 1200 and INR 900 respectively. They are provided on the same day.” A blood sample, given any time of the day can be used for the test. No dietary precaution or fasting is needed for the same. Kids can get tested as well, however, they may require a prior paediatric consultation.
This brings us to the burning question, is it actually helpful to get a test done right now?
How do antibody tests work?
Antibodies are the infection-fighting proteins, produced in response to the virus. It helps your body remember the exposure and recognize the virus. Also termed as immunity tests, a positive test could mean a person has been exposed to the virus.
Dr Amit Saraf, Director of Internal Medicine at Jupiter Hospital says, that these tests denote immune wellness. “Antibody tests rely upon an individual’s ability to launch an immune attack on COVID 19. Once an individual develops antibodies towards COVID 19, then and only then will they be seen in the blood sample and hence will be analysed.”
Another specific type of test, antibody titler test which measures the number of antibodies, is being recommended for healthcare workers and frontline warriors, who face the biggest threat of exposure right now.
In the public sphere, antibody tests can help determine the effectiveness of a vaccine, identify and assist in contact tracing and may even reveal who might be more susceptible to re-infection at a certain point. For a recovered patient, a positive antibody test could also determine if a person is eligible for plasma donation. Antibody tests can offer a lot of input for officials such as how far has the infection spread, the severity and the population size which could be infected.
However, having antibodies most certainly doesn’t mean you are protected. There’s still a lot more medical study needed to ascertain the level of antibodies needed to fight off and prevent COVID reinfection. Dr Rahul Tambe, Senior Consultant, Internal Medicine, Nanavati Super Speciality Hospital feels that antibody tests might work, but they aren’t conclusive. “Antibody tests aren’t conclusive. They work better as a sero-surveillance tool and determine levels of immunization in a certain community. One also needs to know how to correctly interpret the antibody levels to proceed further. Depending on these alone won’t help you determine if you have been had the infection in the past. A reverse RT-PCR test is more accurate.”
Dr Manish Doshi, Head of Pathology, Hinduja Hospital Khar also adds that the tests aren’t approved as a diagnostic tool right now. “It’s a public health measure and not the gold standard. Antibody tests, right now, work the best for those donating plasma. It’s a presumptive test, at best.”
Unlike a COVID diagnostic test, the accuracy of these sero tests depends on two big factors- timing and the type of test you go for. Dr Saraf says that the readings of the tests can also differ on an individual basis. “This process depends a lot on the individual immune system, presence of other medical conditions, amount of infection sustained by the individual etc, hence antibody testing is effective but time to develop antibodies differs individually.”
Should you be getting one done?
Antibody tests can only offer a small glimmer of hope in the current timeline. Right now, there is no one COVID test which is fully accurate. False-negatives are always possible. In the lack of conclusive research, experts are warning that antibody tests may not be the best indicator of immunity right now.
There’s another big limitation with these tests. Antibodies can differ with the time you get tested and show wrong results. However, that doesn’t mean they aren’t effective. It could be a part of the community-driven response to the pandemic and can help healthcare officials identify what needs to be done, who is at a higher risk and deliver a better response to the outbreak.
Dr Tambe also warns that taking antibody tests could make people negligent and ignore the threat of the COVID-19. If you do take a test, you should be looking out for its sensitivity.
Antibody tests can offer preventive satisfaction, but do not guarantee any conclusive proof that you are fully “safe” from the virus. Ameera Shah, Managing Director, Metropolis Healthcare Ltd, adds a precautionary note with their effectiveness. “Even if your test result indicates that you have developed antibodies, it is best to continue to follow all social distancing norms, continue using a good quality mask, frequent hand washing and sanitization.”
