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Understanding Covid sub-variants: ‘If you’ve had BA.2, it can protect you against BA.4, BA.5’

The peaks of the latest wave of Covid-19 infections across the country are likely to be smaller with previous exposure to the BA.2 sub-variant offering better protection against emerging variants as compared to its cousin BA.1. Still, it is time to develop a new generation of vaccines to ensure broader protection against mutations, Dr Anurag Agarwal tells The Indian Express

Why Dr Anurag Agarwal?

Dr Agarwal is a trained pulmonologist, whose research focusses on respiratory disease biology. He was at the helm of the Institute of Genomics and Integrative Biology when the pandemic hit and has been a key expert in the government’s pandemic response. With IGIB being one of the ten hub laboratories under India’s Covid-19 genomic sequencing consortium, Dr Agarwal headed the team till his retirement earlier this year. He is currently the Dean of Biosciences and Health Research at Ashoka University. Dr Agarwal is also the Chair and only Indian member of the World Health Organisation’s Technical Advisory Group on Sars-CoV-2 Virus Evolution.

After the Omicron-driven surge in January, several sub-variants have emerged in India and globally. These variants, as per the genome sequence data uploaded to the global database, are increasing in the country. What’s the impact?

All these variants – BA.2.38, BA.4, or BA.5 – are all what you would call evolutionary branches of BA.2. They are still very much a part of the Omicron family. As of now, the behaviour has been similar in terms of vaccines continuing to protect against severe disease and previous infection continuing to protect against severe symptoms but not against re-infection. But most of the clinical manifestations are mild. So, there is no public health emergency that is new beyond what already existed with Omicron.

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If we talk about BA.4 and BA.5, they certainly can evade immunity from BA.1, but they may or may not evade immunity from BA.2. Take the example of South Africa, which experienced a BA.1 wave followed by a wave of infections caused by BA.4 and BA.5. But because they are derivatives of BA.2, anybody who had BA.2 should get some protection.

India’s third wave was caused largely by BA.2 and this is the reason the current Indian wave hasn’t been very large. However, many got BA.1 as well during the previous wave so not everyone is protected. Delhi started with BA.1 and then developed BA.2, West Bengal was BA.2 from the beginning. The big cities mostly got BA.1 till BA.2 took over. So, you get a little bit of protection because of BA.2.

People who contracted Omicron in January have tested positive during the current surge. Is reinfection common with new variants?

Reinfections are common right now. Those who have taken the booster dose after the January wave are probably a little more protected, but by and large severe disease has been low. That is the reason why we are not coming out with a new classification because the overall threat of severe disease, given the current immunity, has not changed very much. The previous variants seem to be protecting us against severe disease, even with BA.4 and BA.5.

However, there’s a caveat as some new papers show that BA.4 and BA.5 may infect the lungs compared to BA.1 and BA.2. But again it is very modest. There is a trend but nothing major can be observed among the population at large. In fact, some have been pointing out that the current wave is looking a little worse than the BA.2 wave but in reality, it is not looking as bad as the beginning of the December-January wave when the hospitalisations rose significantly more.

Do repeated bouts of the Covid-19 infection put a person at a higher risk of developing long Covid symptoms?

I don’t think there is good data on this. There is one misunderstood paper from America about reinfections. But common sense dictates that repetitive bouts of any infection increase the risk of allied complications. So, each time the risk of severe disease is lower than the previous time, the risk of long Covid or another problem goes up. It is akin to dodging a bullet – so the first time you face bullets, the risk of one hitting you may be 10 per cent. Let’s say it goes down to nine per cent the next time and then eight per cent after that, but there is a risk that you get hit by the bullet every time. Even if developing a complication is a small probability with each infection, the cumulative risk goes up.

Taking reasonable precautions to prevent infections have always been a good idea. Right now, if a surge is going on in Delhi, I would choose not to visit a crowded indoor night club. I might prefer to go to less crowded places with better ventilation. If I have to take a metro, I will use a mask. In my own car, I probably won’t. Outdoors I probably won’t. There is a need for behaviour change for high risk settings.

How protective are existing vaccines against the new variants?

The WHO’s TAG-CO-VAC (World Health Organisation’s Technical Advisory Group on Covid-19 Vaccine Composition) came out with recommendations probably in the middle of June that vaccines, including boosters, are continuing to protect against severe disease. But the protection against infection is down and it is time to revisit the composition of the vaccines.

One line of thought is that BA.1, being the furthest away from the original, the newer vaccines could have the original plus BA.1. You would depend on the concept of antigenic distance to give you the most diverse possible response, meaning the vaccine would cover the maximum distance using two or three variants farthest away from each other.

The vaccines already use the original variant, so if you had to pick one more, it would probably be Omicron and not Delta. World over, the Delta variant-affected are already neutralising because the wave has already occurred. And, the original variant vaccines were reasonably effective against Delta.

After two years of the pandemic, do we now have an understanding of how frequently we need booster shots?

No, we don’t know yet.

So, what is your advice for people regarding their precaution dose?

There is clear data that shows the severity can be somewhat high in people who have taken just two doses. One group that should certainly take the precaution dose is the elderly because vaccine efficacy is lower in that age group and declines also faster.

The only thing that I am waiting for – and there is no guideline yet – is what the third dose should be. You saw the data coming out of CMC Vellore that a third dose of Covaxin is not a good idea. Personally, I think the protein sub-unit vaccines are a beautiful idea.

First published on: 01-07-2022 at 10:25:08 pm
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