Q&A: “We have the momentum” – fighting to end a 60 year-old cholera pandemic

This year, the ongoing seventh cholera pandemic turned 60. Here, Lorenzo Pezzol, epidemiologist and cholera expert, tells #VaccinesWork that we have the tools to end it – and that we really should have done so long ago.

  • 23 December 2021
  • 12 min read
  • by Maya Prabhu
Lorenzo Pezzol
Lorenzo Pezzol


In 1961, a new strain of cholera began to spread in Sulawesi, Indonesia. By 1971, it had reached Africa, and by the 1990s, it was in the Americas too. That seventh pandemic turned 60 this year – a grim milestone. Scientists estimate that it continues to kill between 21,000 and 143,000 people each year, stalking poor and crisis-hit populations.

 #VaccinesWork called up Lorenzo Pezzoli, an epidemiologist who has been part of the fight against cholera since 2014, to talk about opportunities lost, gains made and where we’re headed. That conversation, edited for length and clarity, follows below.

“Is it surprising that cholera is still around? It’s not surprising and, at the same time, it should be. It should surprise everybody. And it should outrage.”

VW: The seventh cholera pandemic broke out in Indonesia in 1961. This year we’re marking its 60th anniversary. More than a billion people are still considered at risk. Is it surprising that this pandemic is still going after all this time?

LP: I think it is. I mean, it is sad; it’s surprising in the sense that we are capable to control and eliminate cholera. We should have done that a long time ago, if you ask me, with the tools that we have. Oral cholera vaccines, of course, in the newest form, are something a bit more recent, but they have been around for decades before that too.

But the fact is that cholera can also be eliminated by ensuring that the population has access to a good water and sanitation structure – which is a basic human right. And from a case-management point of view, cholera is a very simple disease to treat because it’s basically an acute watery diarrhoea that leads to severe dehydration. So the main therapy is providing rehydration to these patients before they lose all their liquids. It’s a simple medical intervention: we’re talking about ORS – oral rehydration solution.

“The stockpile mechanism is providing oral cholera vaccine for emergency situations [...]. This has been a game-changer.”

So when you say, is it surprising that the pandemic is still raging, 60 years on? The reply is yes and noYes, it’s surprising, because in this day and age – and even decades ago – nobody should die of cholera. High-income countries don’t have cholera epidemics. Why? It’s not because they are all vaccinated against cholera. It’s because they have good infrastructure and good access to water and sanitation, which prevents cholera from spreading. And that, finally, is the solution. It’s very sad that other parts of the world are in a situation where, if there is one case of cholera, then an outbreak can easily fire up. And that’s the no part – it’s not surprising, because, unfortunately, there still are a lot of places in the world that are in this condition.

VW: In the 60 years of this pandemic, global cholera control efforts have seen moments of surge and moments of lost momentum. Can you tell us a bit about that?

LP: When the GTFCC was established in 1992, cholera was a truly global problem –  it’s the Global Task Force on Cholera Control. [At the start of the seventh pandemic] cholera affected all the regions of the world – including the Euro region. When cholera was eliminated in the early 2000s from the American region, it became less of a global problem, and the GTFCC sort of went dormant in the next few years. Then cholera hit Haiti again, and put cholera in the Americas again, transforming it into a global problem again. And that’s when the GTFCC was revitalised again.

VW: If I’m reading that correctly, it sounds like the ebbs and flows of the effort to vanquish cholera in the early decades of this pandemic have had quite a lot to do with geopolitics.

LP: You’re reading it right. And it’s wrong. It’s sad. That’s why I am outraged when you asked your first question. Is it surprising that cholera is still around? It’s not surprising, and at the same time, it should be. It should surprise everybody. And it should outrage.

VW: In recent years, the intensity of the struggle against cholera has shifted up a gear. You joined WHO’s cholera team in 2014, the same year that the GTFCC was revitalised, and began working on the operationalisation of the retooled taskforce. Since then, in various capacities, you’ve had a front-row view of the intensified global campaign against cholera. One notable expansion to the arsenal has been the 2013 creation of the Gavi-supported oral cholera vaccine stockpile, which has allowed tens of millions of vaccines to be deployed in response to outbreaks.

LP: This stockpile has been a game-changer – we are all grateful for the stockpile.

The stockpile mechanism is basically providing oral cholera vaccine for emergency situations, and is managed by the ICG. And as I was saying, this has been a game-changer. Among the first “customers”, let’s say, for the stockpile, were people in Haiti, with the first campaigns conducted in 2014.

It’s a wonderful tool, because it puts something in the hands of the decision makers, of the community, of the Ministries of Health – something that is very powerful. They’re not just facing a cholera epidemic thinking, “Oh no, we have to increase access to water and sanitation,” – things that, of course, take time. We have, now, something that can be used even more quickly, and it’s a cholera vaccine. It starts being effective within one week of vaccination, more or less, so if we have cholera confirmed on day one of an outbreak, if we manage to submit a request to the ICG timely enough, we can receive the vaccine in the next few days, within one week. And we can cut outbreaks – we can shut them down. That’s very powerful.

VW: The oral cholera vaccines (OCVs) currently in use against mass outbreaks were prequalified by WHO from around the year 2011. How good are they?

LP: The vaccine is very good. In terms of immunogenicity, it’s perhaps not the best vaccine that humanity has produced – but it has an efficacy above 65%. Two doses protect for at least three years, perhaps longer – we don’t have a lot of data. One dose protects for at least six months, but up to one year.

But one of the major advantages is that it’s a vaccine that is very easy to deliver; it can be quickly delivered to a lot of people. It’s oral, it doesn’t require a big medical infrastructure, and of course, no injections needed. It can be kept in CTC – controlled temperature chain – which means that for at least a couple of weeks it can be kept outside of the cold chain. And so, it’s a vaccine where there is really no excuse for its not being more widespread, and in use at a much larger scale.

And the question is now: why is it that every year we are struggling to meet the [OCV] needs of these countries? Knowing that it is a very good vaccine, and that we have capacity to produce it at a larger scale, why are we not producing it at a much larger scale than what is currently available in the stockpile?

“There’s been a diversion of attention [due to COVID-19]. And of course, with a diversion of attention, there’s been a diversion of resources in a field in which resources are finite.”

VW: Do you have a proposed answer to that question?

LP: I guess I’m wondering if it’s a matter of political will, and yeah, of donor interest. That we are still not scaling up. I guess it’s also a technical issue – if you want to eliminate cholera, you scale up production for a vaccine that will, at some point, not be needed anymore. So you may be investing a lot in systems for scaling up, and then quickly have to close it down.

VW: You’ve worked on mapping out strategies for the deployment of the vaccine. How could we be using this powerful tool better?

LP: We’ve seen the use of the vaccine in emergency situations, where every year it was doubling – first year was half a million doses, and then it became one million in the second year, and then two million. It was a typical virtuous cycle. I think the world should be grateful for the stockpile and Gavi’s investment – and for the prequalification of the oral cholera vaccines – because it really has changed things.

At the same time, countries in a way became used to this, and started using it en masse. And sometimes it almost became like our reaction was – okay, cholera outbreak, we’ll send vaccines. But the vaccines are ideally used just to buy some time. You vaccinate in an emergency, control the spread, and it gives you time to put in place more long-term interventions.

VW: Obviously, in 2020, another pandemic – COVID-19 – collided with our current cholera pandemic. What, in your view, has been the impact of SARS-CoV-2 on cholera control?

LP: There’s been a diversion of attention. And of course, with a diversion of attention, there’s been a diversion of resources in a field in which resources are finite.

VW: Is the effect of that quantifiable at this stage?

LP: I think it’s definitely quantifiable, but is it easy? No, it’s extremely complicated. Indirectly, you can see it. I was just looking at the cholera annual report for 2020, published in 2021, and there’s been a decrease in the number of cholera cases reported globally. And the question – and I don’t think I have an answer yet – but the question is, why was there a growing trend of cholera being reported, more and more in the last few years, and now in 2020, there’s less cholera being reported?

“I’m optimistic that with the right investments and the right human resources, if it’s not achievable by 2030, [cholera elimination] is achievable shortly after 2030.”

Is it because, effectively, COVID measures have enhanced the capacity to control cholera – which would be a positive impact of the pandemic? Increased hygiene, for example. Or could it be – playing devil’s advocate, now – that countries are so focused on COVID that they are completely neglecting looking at cholera transmission? So it’s not, maybe, that there is less cholera, but they are detecting less cholera, because, as we said, their attention is completely somewhere else?

VW: I think you qualify as one of those “attention resources” that has been diverted, am I right?

LP: Yeah, exactly. I’ve been working for the past six months a lot on COVID. Let’s say 80% on COVID and 20% on cholera. And I’m sure I’m not the only one. The people in the Ministries of Health who are normally in charge of requesting vaccination, ICG requests, so on and so forth, have probably been absorbed by COVID. So they have definitely submitted less requests. The cholera team at WHO has been stretched in many different directions; everyone has been stretched.

VW: A tricky time, then, to ask this question – but how are we doing against the target, articulated in the Global Roadmap, to eliminate cholera as a threat to public health (in other words, to reduce cholera deaths by 90%) by 2030?

LP: So now we are 2022, almost. We have eight years. Will we eliminate cholera by 2030? Highly unlikely. At the same time, if you start on the right foot, you’re already halfway there. I think that’s what we should focus on in the immediate future – making sure that countries continue working on their national cholera elimination plans.

“The fact is that cholera is associated with warm and humid climates, warm and rainy seasons. So with climate change – more floods, more dramatic weather events – that will definitely increase the risk of cholera.”

We have, now, mechanisms in place to support countries to do so. The GTFCC that has been [in current form] in place since 2014; the Roadmap was launched in 2017. That was only four or five years ago – and a lot has changed since then. Countries have realised that eliminating cholera is achievable.

Despite limitations I’ve mentioned, there has been an increase in the use of OCV, there has also been an increase in the use of vaccines outside of emergencies, in planned campaigns. The Country Support Platform (CSP) that is hosted by the IFRC is supposed to operationalise the strategy of the GTFCC and support countries directly, and this is going to be very, very helpful.

I’m optimistic that with the right investments and the right human resources, if it’s not achievable by 2030, it’s achievable shortly after 2030.

VW: If I can I ask a final, miserable question – what impact is climate change likely to have on the progress you’re describing?

LP: Yeah. We have to be realistic. Things happen. One was the pandemic. Who knows what effects that will have? We still have to quantify those. And another one is climate change.

The fact is that cholera is associated with warm and humid climates, warm and rainy seasons. So with climate change – more floods, more dramatic weather events – that will definitely increase the risk of cholera, just by the environment. That changing situation does not only affect the environment, but affects the population in that environment, making vulnerable populations even more vulnerable – more susceptible to cholera outbreaks.

The other side of the coin is you have droughts – you have people who don’t have water anymore, people who have to go and drink in puddles and wherever they can find water – in dried lake basins. That also increases exposure to cholera and any other environmental contaminants. It’s not good news for elimination of cholera like it’s not good news for elimination of many other infectious diseases. So as you rightly say, it’s a miserable question. And unfortunately, it’s a very real question.

VW: Well, uh, merry Christmas.

LP: We’ve talked a lot about problems. But we also have to talk about solutions, and how these solutions, especially with regards to cholera elimination, are within our grasp. We have the tools available, we have the momentum, we have the capacity, technically, to do so. Now it’s a matter of doing it. I think we can end on a positive note here.