To prevent measles from spreading further, India needs to immunise 95% of the susceptible population

India, particularly Maharashtra, is currently seeing a measles outbreak. The state has recorded 925 confirmed cases and 17 deaths so far. Meanwhile, China’s government is finally relaxing its strict zero-Covid rules, so patients with a mild case of Covid-19 can now quarantine at home, but the larger challenges wrought by the zero-Covid policy remain.

What is the commonality between what we’re seeing in China and what we’re seeing in India, given the recent measles outbreak is in some ways an outcome of a public health system forced to divert attention to the Covid-19 pandemic? Is our disease surveillance effective, i.e. are we adequately tracking diseases as they emerge, to frame a public health response? We asked Dr K Srinath Reddy, president of the Public Health Foundation of India, adjunct professor of epidemiology at Harvard TH Chan School of Public Health and former head of cardiology at the All India Institute of Medical Sciences.

Edited excerpts:

How are the measles outbreak in India and the relaxation of Covid-19 rules in China connected, in the larger context of disease surveillance?
They’re all connected in the sense that infectious diseases are going to be with us for quite some time to come. It was an incorrect notion that we could vanquish and completely eradicate all viruses and other microbes. Some, we have been successful [at eradicating], but mostly these are going to be part of our ecosystem. How we deal with these in terms of prevention, in terms of surveillance to detect outbreaks early on and take active containment as well as protective measures to enhance the immunity of individuals, are going to be the important measures that public health [policy] must pursue with a great deal of commitment, without letting the guard down.

China did not use the term ‘eradication’; they used the term ‘zero-Covid’. That means they [aimed to] prevent any [new] case of Covid-19 in the population after the initial experience. The idea was to keep a lid on the Covid-19 virus, and completely prevent transmission, so that new cases would not occur even in terms of infections, let alone serious cases and hospitalisations. That was not a strategy that could endure.

In the initial stages, [a zero-Covid policy] was okay, because we were dealing with a novel virus. There was a considerable threat of serious disease, hospitalisation and death. Therefore, some of the measures taken in terms of lockdowns were perhaps justified, in the sense that [China was] very scared of the Delta [variant], because they saw the havoc being caused by Delta. But even when Omicron [variant] came in, [China] continued the same strategy. And the population levels of immunity, which could have occurred because of some levels of natural infection, had not really happened. Also, many sections of the vulnerable population – especially the elderly – were not vaccinated enough, so they did not acquire immunity through vaccination.

So [China] felt that if they opened up, [the vulnerable] were likely to face a further threat, and they continued the [zero-Covid] strategy far too long. If, however, they had opened up in stages, and had seen the evolution of the virus into the relatively less dangerous Omicron variant, they could have actually been in a far better place than they are now. Perhaps now that they are opening up, they will face some challenges initially, because of the under-vaccinated, vulnerable sections of the population that are likely to get exposed. But overall, I think, they’ll do better than they would have with a continued commitment to [zero-Covid].

Is China’s opening up in any way could be a threat to the global health, which has in some ways moved on [from Covid-19]?
I don’t think so, unless some sort of new, dangerous [Covid-19] variant emerges from China, [if there is] admixture of Omicron as well as some preexisting variant strains. Because, the rest of the world has experienced the original ancestral virus, then the Alpha [variant] in some measure, then experienced Delta and now has learned to live with Omicron over the past year. So, I do not think the rest of the world is going to be seriously threatened if Omicron starts spilling out of China, even in terms of new Omicron sub-variants.

This is also because countries like India are enjoying either a very high level of vaccination, or have developed a high level of [natural] immunity [from a prior Covid-19 infection]. Would that be correct?
Absolutely. India has actually achieved a high level of immunisation. And even though we may say that the antibody levels may fall after five to six months [after the last vaccine dose], the memory cells and T cells remain, and they are likely to offer long-term protection. Therefore, given both the high rates of Covid-19 infection as well as high rates of vaccination in India, there is enough [immunity] to fall back on for most people. We must still keep the guard up for vulnerable people in the elderly age group and those with comorbidities. However, we also need to ensure that vulnerable people are not dependent only on vaccination, but also use appropriate measures like masks in crowded, ill-ventilated places.

Most Indians have not received further Covid-19 vaccine doses after taking the third dose. Some have not been immunised further after the second dose. What does that mean vis-à-vis our current state of immunity, considering that for many, the third dose too was received six months to a year ago?
At the moment, I think the government is watching the situation and trying to gauge the evidence. But, speaking for myself, let me put it this way. The protection that we are trying to get from Covid-19 vaccines is against severe disease, hospitalisation and death, because now it is abundantly clear that the vaccines – even the new versions – do not prevent transmission of the virus if you’re exposed. If you get exposed to a person with the virus, and you’re not wearing a mask, you’re likely to get infected, but the vaccine prevents you from getting severely ill.

Now, you have people who are reasonably immune from prior exposure to vaccines or infection, and they’re unlikely to get severely ill. Young people are unlikely to get severely ill. So the only people who are likely to benefit by way of prevention of severe illness on exposure to the virus – from a booster dose or an additional dose, now that the previous immunity is waning – are the elderly and persons with comorbidities. The rest of the population, I do not think of as candidates for mass vaccination at this point in time.

So if you’re older and/or have one of the comorbidities, then you should definitely be lining up for your next dose of a vaccine, regardless?
Yes. It’s a ‘no-regrets’ policy.

Coming back to measles. Maharashtra is going to see a measles-mumps-rubella vaccine initiative starting December 15, that is trying to target those who have not been vaccinated for various reasons. What does this tell us?
The problem is that partly because of Covid-19, and then even after the Covid threat had eased, our health system had not got back into full gear on immunisation. A variety of health services slowed down during the pandemic, and they did not really get back full steam even after Covid, because they were recouping. Further, we were also in the Covid-19 vaccination mode. There were so many ways that Covid took our eye off other health conditions.

As a result, we did see measles vaccination rates drop, along with many other essential health services. We know that 95% of the susceptible population has to be immunised if you have to prevent measles from spreading. Now because the immunisation confers about 95% [protection] even on the first dose, but if only 90% or 85% people have been vaccinated, then the virus can spread. And the [measles] virus indeed can be very infective. One infected person can infect up to 18 people in the unvaccinated group. Therefore, [the measles outbreak is] the natural consequence of the slippage in vaccination rates, either because some sections of the population are refusing to get children vaccinated, or because the health system itself moved to a slower gear.

What are the health challenges that remain hidden because of both these reasons, health systems having to divert their attention elsewhere, or people’s hesitancy and resistance?
Our health systems are now getting back into gear. We were able to detect these cases, even though the surveillance systems may not have picked up all the cases yet. Nevertheless, the fact is that these outbreaks are being reported upon and there’s a fairly ready response now, in terms of increasing immunisation, giving supplementary immunisation doses and getting the reporting systems fairly active. I think our response is fairly strong at the moment. But this is because right now, we are sensing that there is a problem which could mount if neglected, but I think we need our overall disease surveillance programmes to be greatly strengthened. And unfortunately, there are several challenges here.

First, we have data flows in our surveillance programmes, starting from the district level, going up to the state level and to the central level. Then, the information after analysis flows back to the state and then to the district for action. There’s so much delay in that process. We require a much more prompt response. Because what surveillance means is data collection for action. Here, we have data collection, but we’re not getting prompt action.

Thus, we require both horizontal and vertical integration of health data dissemination. That means while the data must flow to the Centre, we must have the data being shared rapidly at the local level, primary health centre level, block level, district and state level for ready action. That kind of integration is being facilitated or being contemplated through digital technologies, and not just through the digital health mission. [Some] are actually trying to [create] this kind of vertical and horizontal data integration. Uttar Pradesh has taken a lot of steps in this direction. If that happens, then you’ll get prompt recognition [of disease outbreaks] and a ready response and that’s what we need.

Secondly, we must also get over this problem of multiple datasets being demanded because of different health programmes. We have duplication of data. For example, if somebody has fever, the auxiliary nurse midwife, a village-level female health worker, has to report the fever both to the National Centre for Vector-Borne Diseases Control programme as well as to the Integrated Disease Surveillance Programme. We need a much more integrated format so that this pressure or load on the frontline health worker is reduced. At the same time, we will have reliable and timely data collection which can be analysed and lead to a rapid response.

There are many ways in which we ought to do this. We have innovations, for example measles surveillance was added to the acute flaccid paralysis (polio) surveillance programme by Karnataka in 2006-’07, and that has now become a nationally replicable model. So we ought to get multiple data sets assembled in the most efficient manner possible through a variety of disease control programmes joining their efforts.

If you were to have a dashboard for disease surveillance, what are the parameters that you would want to look at today, in the post-Covid context, when we are seeing the first outbreaks of diseases like measles? What are the data gaps that you would want to fill?
Essentially, we know that we’re looking for some of the febrile illnesses, illnesses with respiratory symptoms, illnesses with rash, exanthematous fevers like measles, fever with diarrhoea. Even when we looked at Covid, people were looking for an influenza-like illness, or a serious acute respiratory infection. We know exactly what the broad common features are across a variety of infectious diseases. These important elements are the kinds of things that we want to be reported on.

If you were to look ahead now, given what we’ve seen with the measles outbreak and what health systems have missed because of the pandemic, what are the specific signals that you would be concerned about? Are these the same that you just mentioned?
Just about the same. For example, we know that there are vector-borne diseases which cause fever, and viral illnesses of various kinds that we have been dealing with in the recent past, like Covid-19. So there are a number of common features which act as alerts, and there are some distinctive features which help us distinguish between [diseases]. We can actually prepare that set and have diagnostic algorithms assembled along with the data reporting systems.

You described to some extent what the disease surveillance system looks like today, and the multiplicity of data. If we were to build on that further, either at a consolidated national level or regional levels, what kind of blueprint comes to your mind?
As I said, surveillance has to be most efficiently done at the local level, in terms of accurate and timely data collection, as well as data analysis for early response action. Obviously, everything cannot be decided upon at the Delhi level; it has to be done at the local level as well. That is why we need efficient data collection systems, and also analysis to be done at multiple levels. And the moment we can cut that short, with, as I said, both horizontal and vertical integration of data through digital systems, we’ll be much more efficient.

Having said that, there is also a health workforce element. We need people in the frontline to be trained. We need a variety of other technical people, like virologists, to be trained, and then we need field epidemiologists. We had a field epidemiology training programme being run, which is absolutely essential to train people. But even where people have been trained, they’ve not necessarily been retained in those positions. With the kinds of transfer systems in states, somebody who is a trained field epidemiologist is [placed] somewhere else, and then the fieldwork that is required for infectious disease control suffers. So we need much better manpower planning, both in terms of numbers and skills, and also in terms of committed deployment in the most efficient manner.

Among the many public health challenges we face in India, would you say that spotting surveillance of infectious diseases would be at the top? Where would it be in the hierarchy?
Even though we are seeing other diseases coming up, non-communicable diseases such as cardiovascular diseases, diabetes and others, the immediate acute threat to a population in terms of a major epidemic outbreak is from infectious diseases. Other diseases do require surveillance. People would like to know whether hypertension rates are increasing or not, and what’s happening in terms of tobacco consumption and so on. But the immediate urgency comes in terms of a threat, the so-called negative externalities, because if I get infected and I’m infecting 18 other people, that’s a very serious threat. Thus, the positive externalities of controlling infectious diseases are much higher immediately.

For that reason, I think infectious disease surveillance has to become much stronger. But our health systems cannot run only on one leg. They ought to be able to look at other diseases like cardiovascular disease, diabetes, and all of them, and track these and see whether those rates are increasing or decreasing and whether our programmes are effective or not.

We’ve lowered our guard on Covid-19 in many ways, arguably rightfully so, because we have to get on with our lives. You can now board an aircraft or walk through most public spaces without mandatorily needing to wear a mask. That’s a given now and could be for some time. Given that, and knowing what we know about Covid-19 today, is there a level of guard lowering that you would recommend? For instance, saying ‘do go ahead and enjoy life, but here are the one or two things that you should still be careful of’, considering that Covid-19 is still so fresh in our minds?
I think purely in terms of, as I said, a ‘no-regrets’ policy. If somebody is entering a closed space which is ill-ventilated, particularly in winter when air circulation is not very fast, I think wearing a mask would be the sensible option. If somebody in the vicinity appears to have a respiratory infection, whether it is influenza, Covid, just a common cold, or something else, it’s sensible to put on a mask. We have been freed from having to wear a mask compulsorily, but retaining it as a sensible option on occasions is still useful.

This article first appeared on IndiaSpend, a data-driven and public-interest journalism non-profit.