The Tuesday Interview | 'One dose of vectored vaccine for all first is not a bad strategy'

In winter, we could see a potential increase driven by weather and people’s behaviour, says the noted virologist

One of India’s foremost virologists, Gagandeep Kang, a professor at the Christian Medical College (CMC), Vellore, has been closely associated with Covid-related research and policy initiatives from the beginning. Since last year, Kang, the first Indian woman scientist to be elected a Fellow of the Royal Society, has been an ex-officio member of a working group on Covid-19 vaccines established by the Strategic Advisory Group of Experts at WHO. In an interview with DH’s Kalyan Ray, the noted scientist talks about the expected third wave, the Delta variant and India’s vaccination strategy.

When do you think the third wave will happen, and will it be as ferocious as the second?

The third wave would depend on our behaviour. If we have people who don’t pay attention to masking and crowding norms because restrictions on movement have been lifted, there is a strong chance of a third wave. But given the fact that a very large proportion of our population has already been infected, if we are careful, we may not have a bad third wave. If we get a new variant and if it is highly transmissible or if it can break through the immune response, then the chances (of a severe third wave) are high. Otherwise, the chances are that we won’t have a bad third wave.

Respiratory viruses generally like the cold dry weather, mostly winters, and this virus is behaving reasonably similar to that. In winter, we could see a potential increase driven by weather and people’s behaviour.

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Do you think that Delta or Delta Plus variants will continue to have a role?

At the moment, Delta is the most transmissible virus that we have. Delta Plus does not seem to be any different from Delta, though we haven’t seen enough cases of Delta plus. It does not appear to be a cause for concern. The same mutation that makes Delta into Delta Plus also happened in Alpha (variant), but we didn’t call it Alpha Plus. It did not behave differently from Alpha. What we find in the laboratory from sequence data can predict danger but doesn’t prove it. The proof has to come from people and the population. Though we see reports that for Delta, the antibodies are less and (vaccines) won’t protect, when we look at the actual data, people have been protected quite well from severe disease and death. The final proof always comes from field studies on people.

Typically, how long does it take for a virus to mutate into a dangerous form?

These are RNA viruses. They are mutating all the time. Since the mutations are random events, they can go into many different directions. There can be mutations that make no difference, mutations that are bad and mutations that are good for the virus, allowing them to be replicated even in people who have been vaccinated. The mutations that allow the virus to escape the immunity and give better transmissibility matter for the virus. As the virus is in so many people, it has multiplied trillions of times, but we began to see mutated viruses in December. Many such mutations were present earlier, but they reached a take-off point to spread in the population in December.

Since then, we have seen five such viruses in seven months. To predict how often we are going to see mutants that are of concern to us, we need to see how many (Covid-19) cases we see in the world. Though we have some element of control, right now we are at a stage where we see half a million new infections every day and most of them are driven by Delta. The world will go through such a Delta wave at least for another two-three months.

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Is there any way to prevent the evolution of Delta into a more dangerous variant?

The only way to prevent evolution is to check replication. If we stop the virus from multiplying, that’s the only way to suppress the virus’s ability to mutate. But to see what the future might look like we need more virological studies and sero-surveys that would tell us how much of the population is exposed. In India, we have done sero-surveys either for individual cities or in 70 out of 700 districts. But now, we should tell the individual states to do their own sero-surveys and use that to make their own decisions on vaccination.

So far, breakthrough infections have been seen primarily among healthcare workers. Is it possible that more such infections are going to be seen in the general population?

Of course. The question is, will they be picked up? If you have a mild infection and if you are a healthcare worker, it’s easy to get tested. But if you are in the general population, then the chances of getting tested for a mild infection is less. The other question is to consider whether breakthrough infections will increase with time. The protection from vaccines is very good initially, but will breakthrough infections start in six months or a year or in two years’ time? We would not know until we track them.

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Does a single dose of vaccine work as there are reports claiming that both doses are necessary?

The data is showing that a single dose of vaccine works. The global thinking is that we should give one dose of vaccine to everybody around the world before we think of the second dose. Yes, it’s important to get the second dose, particularly for those who are vulnerable. But for the general population, even one dose offers good protection. We know from the UK data that one dose of AstraZeneca vaccine (same as Covishield) gives 71 per cent protection against severe disease and hospitalisation. It’s much better than what we had hoped for last year. The only question I have is that with inactivated vaccines (like Covaxin) we don’t understand the single-dose regimen better. For a vectored vaccine, a single dose for everyone first (before starting the second dose round) is not a bad strategy.