With the surge in COVID-19 cases in China, after the easing of its stringent zero-COVID policy in December, there is apprehension that the pandemic could be entering a new, uncertain phase. In a conversation moderated by Zubeda Hamid, Soumya Swaminathan and Giridhara R. Babu discuss the situation in China and the potential impact in India. Edited excerpts:
Q /
China is witnessing an explosion of COVID-19 cases after the easing of its zero-COVID policy. What is happening? Can this have an impact on India?
A / Soumya Swaminathan: We’ve now completed three years, we are into the fourth year of the pandemic. One thing that’s become clear is that this virus is not going away any time soon. What we’ve also seen is the remarkable capacity of this virus to evolve. Now, specifically in China, because they had such a strict zero-COVID policy over the last few years, there was very little natural infection that occurred, and the only protection people have is from vaccination. Unfortunately, in China, the rate of vaccination in the over-60s is less than ideal. As we know, if you’re an older person, you have underlying co-morbidities, chronic diseases, and the risk of getting severely ill is much, much higher. That is why there is this concern today that in China, not only can the Omicron sub-variants cause huge surges in infection, but this could translate potentially into a significant amount of both morbidity and mortality.
A /
India is in a different situation because we have high vaccination coverage, including among the elderly. What we don’t have is very high booster uptake. But there’s been a lot of natural infection over the last three years, and therefore people have built up a good level of protective immunity at the population level. This should be good enough to prevent an infection surge translating into hospitalisation or mortality surge.
A / Giridhara R. Babu: From the epidemiology perspective, any wave or an outbreak can occur as a result of three important things: how the agent is changing (here, the virus), how human beings are immune, and finally how the environment is facilitating this transmission. Among the three factors, there is an advantage for India and other countries where the host immunity is better, whether because of hybrid immunity or relatively expanded vaccine coverage. But we should remember that this is not a static concept. This is a dynamic concept, which means the immunity in the host keeps changing when you have a virus which is evolving; whether antibodies are lasting long enough, or immunological memory is strong enough to prevent further attacks from newer avatars of the virus are questions we need to investigate. So far, we have the advantage in terms of hybrid immunity. The weak point is in terms of low booster coverage, which needs to definitely be enhanced, especially for the elderly, where 50% haven’t got it, and for all adults. Although the booster dose is important, each day millions of young adults are being added into the population cohort. So we should also ensure that they are vaccinated. Without this, the dynamic equilibrium will be lost.
Q /
India has now administered over 220 crore doses of the vaccine. Since we know the coronavirus keeps on mutating, with new variants of concern, what does the scientific evidence tell us about getting heterologous booster shots?
A / Soumya Swaminathan: This is an important question. We have to base our public health advice on data. The first is your own age, state of health, etc. The second thing is time since vaccination or infection, we know that immunity wanes. The third is the virus and we know that since Omicron emerged, it became so transmissible that even higher levels of neutralising antibodies were not able to prevent infection completely. So the third dose, what it does is really to stimulate the immune response, remind the immune system about the antigens and prepare the immune system to face any infection that it may see.
A / How many boosters do we need? How often do we need these boosters? Is it going to be a yearly phenomenon in the future? These are still open-ended questions. Again, we need good data because the population profile is different in each country. The vaccines that were used are different. From studies done so far, the data point towards an advantage to heterologous boost, which means that if you’ve had the first two shots with an adenoviral-vectored vaccine, and you get a third shot with a protein subunit or an mRNA vaccine, or the other way around, probably what it does is it helps to stimulate different arms of the immune system. There’s still limited data. But regardless of which is used, I think the third dose is important for all age groups; the fourth dose perhaps only for those at high risk.
A / Giridhara R. Babu: A third dose has shown evidence almost all over the world of effectiveness against the newer variants, including Omicron. Which means even though the vaccines are not specific to Omicron, the booster dose has helped to mount an immune response against the newer lineages. Having said that, the evidence for the fourth dose or frequent doses or even an annual vaccination schedule for COVID-19 is not there yet. That’s where most of the confusion is, because there are countries which have done four and are preparing for the fifth, and there are countries which do not have enough vaccines to cover the primary vaccination schedule. When you have such heterogeneity at the global level, each country should have its own evidence base.
Q /
The Union Health Ministry has said States must resume genome sequencing of new COVID-19 cases. How well are we doing in this regard in India? Does it need to be stepped up in the light of new variants emerging?
A / Soumya Swaminathan: Genomic sequencing and surveillance have played a very important role in this pandemic. In fact, if you look at GISAID, which is the database that hosts the whole genome sequences of the SARS-CoV-2 viruses, there are approximately 14 million whole genome sequences; about half of those are from the Omicron strain alone. When we think about genomic surveillance, it’s important to be very strategic about it. There needs to be good representativeness from, say, across the different States, because sometimes you can have blind spots. If you looked at the data from India — for example, INSACOG (Indian SARS-CoV-2 Genomics Consortium) — I think over 25% of samples come from Maharashtra alone. If you have very limited samples coming from other States, then you may actually miss what’s going on. We should be clear about who we are sequencing. All of this needs real-time data collection, but also analysis, reporting and public health action. Otherwise, it’s of no use as an academic exercise. I think that’s where probably we can do a little bit better, in terms of how we are quickly able to use the data coming out to take public health action.
A / Giridhara R. Babu: INSACOG is a consortium of labs, and as a consortium, they’re doing really well with their stated objective. But we have to take one step back. To give an example, not all the labs are connected to the IHIP (Integrated Health Information Platform) now; that means there are several other hospitals and labs that need to be connected to the platform. So what we need to do is integrate the surveillance mechanism at the peripheral level, expand the infrastructure, have the consortium, not just the labs, but also of the hospitals, and connect it to public health actions.
Q /
Would you say that there are no real concerns with regard to another wave in India per se, but we still need to continue to be masked and taking other COVID-19 precautions through this year as well?
A / Giridhara R. Babu: Whether there’s a real concern from the existing lineages in China or elsewhere, it doesn’t appear so for hospitalisation and death, but there will be a greater risk when a new variant develops. So we need to follow the signs in terms of understanding where the new clusters are developing. What kind of symptoms are there? What is the genomic sequencing of that? And then what is the population immunity status level there? And from there, take the next step in terms of whether we should have more stringent [rules] or not. Currently, there’s more of panic, less of a systematic strengthening in most countries, and panic should not drive pandemic control.
Dr. Soumya Swaminathan is former chief scientist of the World Health Organization; Dr. Giridhara R. Babu is professor and head of Life Course Epidemiology, Indian Institute of Public Health, PHFI, Bengaluru