Even as many months have passed since the world went on a lockdown mode to combat the novel COVID-19 pandemic, the world is still in the midst of an ongoing deadly battle. With no definite vaccine in sight so far, the weapons at our disposal are precautionary measures and testing. The uptick in cases, especially in cities like Mumbai, Delhi, Chennai and Ahmedabad has put a question on everyone’s minds about effective testing procedures and how to go about it. The Indian Council of Medical Research (ICMR) recently issued advisory guidelines for testing which included a list of approved antibody test kits among other existing test guidelines. With the need for more tests and that too effective testing in India, it becomes crucial to look at the new strategies employed for combating corona.
The new strategies include Rapid Point-of-Care (PoC) Antigen Detection Test (for diagnosis along with RT-PCR) and Antibody test. The antibody test is used for screening the presence of antibodies present in your blood. The body makes these when fighting an infection like COVID-19, and it also happens when you take a vaccine shot. And this is a part of building immunity against the virus. The antibody test doesn’t check for the virus but checks if your immune system has responded to the virus. The test looks for IgM antibodies, which happen early in an infection and IgG antibodies, which are more likely to show up later. However, the tests are for surveillance and not really for diagnosing COVID-19. However, for diagnosing COVID-19, the RT-PCR test is the gold standard test, which detects the virus’s genetic material. Apart from this, the diagnostic tests also include the antigen tests which detect specific proteins on the surface of the virus.
So the discussion now comes to the question, which of these tests are more effective? And should we go for antibody tests or just stick with the RT-PCR testing? The answer is that we need both to effectively combat and control the spread of the virus. The RT-PCR tests helps the doctors know if the patient is infected, and helps track the recovery. Whereas the antibody test helps to understand if the patients have been infected in the past and also understand the extent to which the virus has spread within a community. In terms of knowing if someone has been infected, the RT-PCR test is important for diagnosing and identifying active cases and is usually a very accurate test. Antibody test is a surveillance test and not a diagnostic test, as it lets you know about the presence of antibodies. And antibodies take time to develop and there is no clarity on how long they will protect the patient.
With cities where the number of cases are extremely high, the way to go would be getting as many tests done and employing diagnostic tests as well as antibody tests to better manage the situation. Just sticking to one test, like the RT-PCR test won’t help in populated areas, and the testing rates need to go up. More diagnostic tests need to be done to ensure testing rates also go up and more patients can get the proper care sooner. In positive cases, these will help to sooner identify who need to be quarantined and self-isolated by contact tracing. And antibody tests will help knowing who had COVID-19 and recovered, including asymptomatic patients. And this will help in getting data about who has the immunity to fight the virus, and even help in contact tracing. It will give information on how far the infection has spread within a community and who else is at a risk of contracting the virus.
Ultimately, all of these tests and their data need to be combined to help in creating better strategies and approaches for treating the virus.
(Disclaimer: Dr. Laxman Jessani, Consultant, Infectious Diseases, Apollo Hospitals. Views expressed are a personal opinion.)