Dr Alap Christy, Scientific Business Head-Clinical Chemistry & Head Quality Assurance- West SBU, Metropolis Healthcare talks about booster shots for COVID-19 and importance of antibody assessment
Omicron has been a latest newcomer stealing every newspaper’s front page since last month. While the infection has been mostly mild and hasn’t caused serious damage so far, authorities have strictly insisted not to take it lightly. People who are not yet infected have the quest – are we ready for the attack? We have taken two Jabs of vaccine nine months back – are we still protected? Is there any test available which can tell us our protection level?
Government recently started a precaution dose of COVID vaccine. Its too early to comment on the protection levels considering the new variants being constantly evolving. Major worry is amongst the parents whose children have not been vaccinated yet and paediatric jab is still under discussion. Some states have started the schools and colleges. There is little inhibition, as far as mass gathering is concerned. Its winter where respiratory tract infections likely flare up. All situations add up to the anxiety leading to a quest – will I be infected?
Well, for those who do not know Antibody tests – there are majorly three types. 1) Spike Antibody Tests which shows levels of antibodies which prevent binding of virus to human cells 2) Nucleocapsid antibody test which is generally used to detect exposure to virus in recent past 3) Neutralising Antibody Test which tells you how much potential antibodies carry to neutralize the virus. There are overlaps and limitations of each test. Traditionally gold standard test for neutralizing antibody is PRNT (Plaque reduction neutralization test) which is done in high biosafety level labs since it includes involvement of live virus. Scientists came up with an alternative solution to this in the form of a pseudo- neutralization assay where the test can be done using simple ELISA technique without involvement of live virus. Though it can never replace PRNT, it can give much faster results with much less safety requirements. It gives you the virus neutralization capacity in terms of percentage.
Let us be clear, predicting your chances of getting “INFECTED” with COVID is not possible right now especially in view of new coming variants. Also, there is a component of cell mediated immunity which is not largely explored and hence using lab tests to get your protection level is still a dream. However, there is a small ray of hope when we combine all antibody tests. If a neutralizing antibody test gives a percentage neutralization potential and spike antibody gives an amount in terms of titre, its highly likely that people with high titre of antibodies having good neutralizing potential will have a better protection and chances of less severe infection. However, to keep in mind – no antibody test should be used to predict the need for booster Jab.
COVID is still a step ahead of us, but now at least we are better prepared. Let us use the knowledge wisely and take booster shot when its your turn.