Dr. Dennis Carroll: How Can We Prevent the Next Pandemic?

“The viruses that we do know are only those that have already caused great harm, but we know that that’s less than 1 percent of all the viruses that have that same potential. Those viruses are currently circulating in wildlife today. The next pandemic, the next epidemic virus already exists.”

Interview

Key Takeaways

Below are some of the main takeaways from COVID-19 Africa Watch’s conversation with Dr. Dennis Carroll, Chair of the Global Virome Project, a collaborative scientific initiative to discover zoonotic viral threats and stop future pandemics.

  • The regions with the highest likelihood to be hotspots for future zoonotic virus outbreaks are usually areas with intensified activities that bring human populations and wildlife or livestock into closer proximity, creating a higher risk of spillover events of viruses into human populations.
  • When zoonotic viruses first make the jump from animals to humans, they are “clumsy” and inefficient, but the more time the viruses have to circulate among humans, the better they can select for mutations that confer efficiency of transmission. Therefore, finding viruses early on in the transmission process is essential.
  • Simple behavioral changes both pre- and post-outbreak (like lowering risks at live animal markets through good hygiene and not collecting animals together, but also wearing a mask, personal hygiene, and keeping a safe distance from each other) can dramatically lower the risk of spillover events from happening and from spinning out of control. This requires widespread awareness-raising, while avoiding the over-politicization of prevention measures.
  • The viruses we know about are only those that have already caused harm, and those make up less than 1 percent of all the viruses that are potentially harmful to humans and that are currently circulating in wildlife. To better prepare ourselves, the global strategy to pandemic forecasting and prevention should move from focusing exclusively on event-based surveillance and monitoring, towards a broader vision of a surveillance that targets wildlife animals, livestock, and the interface between the animals and people.

The interview was conducted by Lilian Best, an IFC-Milken Institute Capital Market Scholar who works at the Central Bank of Liberia. A transcript is available below.

Transcript

Interviewer

Hello, my name is Lillian Best. I work with the Central Bank of Liberia, and I’m an alumna of the IFC Milken Institute Capital Markets Program. I’m delighted to welcome Dr. Dennis Carroll, who leads the Global Virome Project, which aims to conduct animal and human population surveillance. Prior to that, Dr. Carroll, you directed the Pandemic Influenza and Emerging Threats Unit at USAID for nearly 15 years, where you spearheaded the Predict Project, among other initiatives. Predict is a project that identified more than 2,000 zoonotic viruses. You’ve been described as, “the US federal government’s virus hunter”, and “the man who saw the pandemic coming”.

So let’s start at the ten-thousand-foot level here. How do we predict a pandemic? What framework and what mechanisms do you use to identify a viral threat that has pandemic potential?

Dr. Dennis Carroll

Thank you first off for the opportunity to join this discussion. I’m delighted to be here. Let’s be very clear when we talk about predicting a pandemic. It’s an incredibly imprecise world we live in. So it is not saying which virus, which area, and what time there’ll be another pandemic. Instead, it’s a bit like hurricane forecasting. We know that there’s a period of the year that it is more likely to see hurricanes than others. And so there are projections that there may be a certain number of hurricanes over the course of the year, but you don’t know exactly what, and you don’t know exactly when; you just have some sense that we need to be forward-leaning and preparing for a potential hurricane.

Predicting a pandemic is somewhat similar. We know that first and foremost, there are certain hotspots in the world. The viruses that we’re most concerned about, they already are circulating in the world around us. So we’ve been able to develop hotspot maps that look around the world and say, this region is more likely because we understand that the biggest single driver propelling a spillover event (the jump of a wild virus into human populations) is where there’s been an intensified increase in human activities, bringing human populations and wildlife in closer proximity, or our livestock in closer proximity. So, where we’ve seen these population pressures – expanding our urban settlements, expanding our agriculture into areas that are rich with wildlife – those places are most likely to be hotspots for a future threat.

Interviewer

In that exercise of forecasting, could you tell us a bit more about these zoonotic viruses and how you do surveillance to detect them? And you conduct that surveillance on both humans and animals. What does that look like? What are the blind spots that you have seen and how do you correct those blind spots?

Dr. Dennis Carroll

Okay, first, in the work that we did in Predict over a 10-year period, Predict was really helpful in helping us understand which are the wildlife animals species that we should be paying attention to. Largely, we’re talking about mammalian animal species and waterfowl. Those are the two big reservoirs for potential future threats, but Predict was really helpful in narrowing that down. There are over 5,000 different species of animals, of mammalian animals, and you can’t watch all of those. And Predict was really helpful in helping us to understand which are the greatest likely hosts for a future spillover event. It’s largely those species of animals that are highly interactive with human settlements. A lot of mammalian species, when we move into their wildlife domain, scatter and move away. They do not co-exist with us, but there are certain animal species that do. We know that obviously. Rats have learned to co-exist with us, or we’ve learned to co-exist with rats, over a very long period of time. It’s the same thing with bats.

We see bats living in urban areas much more frequently than we do other wildlife species. So Predict was really helpful in helping us understand that if you’re going to do surveillance, you’re going to most likely find those viruses that we’re concerned about (that is, the ones that have the chance to jump to us) in the animals that are living most closely to us.

So first off, learn from experience. Learn from what has been a problem in the past and use the brilliant advances that have been made in genomics and genetic analysis that allow us to look for nearest neighbor viruses, and then pay attention to those because they’ve shown their ability to infect us. By contrast, most viruses, when they come close to us, don’t have the right kind of physical properties that could ever lead them to infect us. It requires a special combination of genetic features which most viruses don’t have. So look for those viruses that we know that have that pedigree in the past.

“The more time a virus has to circulate in us, the more it can really select for mutations that confer efficiency of transmission.”

We see that right now with COVID-19. We see different variants that are circulating around the world, and the longer they’re out there infecting people, the more they have the ability to evolve and get better. The more time a virus has to circulate in us, the more it can really select for mutations that confer efficiency of transmission.

That’s why you want to find this virus at the very beginning. When it first spills over, it is very clumsy, it is very inefficient. And if you capture it, then it’s very controllable. But once it becomes a very efficient virus  – we’ve seen with this pandemic, the COVID-19 virus –  it’s really difficult to put the genie back in the bottle. It becomes a very difficult task.

Interviewer

That’s really concerning given that despite international efforts underway to increase access to vaccine in Africa, notably through the COVAX initiative, some estimate that we may have to wait until 2023 in order for Africa to reach herd immunity!

When we look at this, we start to think about how to change behaviors. Because you’re not going to change the animal’s behavior, maybe even when it takes just one or a few animals to infect a human population. It’s the human beings in the population whose behaviors we can change to stem the tide. But culturally, there’s this resistance to just wearing a mask and all the way to taking a vaccine. What do you do, over time, to shift our behavior and make it a part of the culture to really be conscious of this, especially as populations continue to spread into the natural habitat of these animals ?

Dr. Dennis Carroll

Well, you’ve really identified a critical issue here. It’s our behaviors. It’s not the bats’ behaviors, is our behaviors.

“First and foremost, we need to understand what is it that we’re doing that allows that spillover event to happen.”

First and foremost, we need to understand what is it that we’re doing that allows that spillover event to happen. There are very practical, usable things we can do that will dramatically lower the risk of spillover events from ever happening. We know that they are simple (wearing a mask, personal hygiene, and keeping a distance safe distance from each other). But as you said, unfortunately in the age we’re living in right now, those incredibly effective prevention measures have become highly politicized.

And I should further note that vaccines really are the most important tool that we have. We should just be in awe of the fact that we have so many different kinds of vaccines, one year after this pandemic began. This is extraordinary. And that we have the opportunity to really stop this pandemic in its tracks, by making these vaccines available to everyone. But as you noted, there are many people that are and will be resistant to receiving the vaccine, which further elevates the risk that the virus continues to circulate uncontrolled within our population. The virus is just exploiting our own stupidity. And it is really unfortunate that our political leaders have turned valuable public health tools into political weapons.

“The viruses that we do know are only those that have already caused great harm, but we know that that’s less than 1 percent of all the viruses that have that same potential. Those viruses are currently circulating in wildlife today. The next pandemic, the next epidemic virus already exists.”

The viruses that we do know are only those that have already caused great harm, but we know that that’s less than 1 percent of all the viruses that have that same potential. Those viruses are currently circulating in wildlife today. The next pandemic, the next epidemic virus already exists.

And it’s circulating in a bat, in a rat, in a non-human primate, it’s out there. And our whole global strategy has been to sit and wait for that virus to begin spreading in humans. And then we react to it. And we see what that means in terms of COVID-19 pandemic. That’s what the Global Virome Project is about: let’s go to the viruses before they come to us. And by going to the viruses, let’s understand which are the greatest potential threats, understand what animals they are circulating in, understand what part of the world, what communities they’re circulating in, and understand what are the behaviors that are enabling those viruses potentially to jump from their natural hosts into us, and use that knowledge to be victorious.

Interviewer

Now you’re working with FasterCures, which is the Milken Institute’s center devoted to accelerating biomedical innovation. And it recently launched an initiative to build a global early warning system that detects and responds to emerging pathogens with pandemic potential. Can you tell us about what we should be prioritizing in terms of an early warning system and what is realistic and affordable, particularly for African countries?

Dr. Dennis Carroll

Right now, it means expanding our surveillance from focusing exclusively on an event-based surveillance, which is just monitoring for an outbreak. We need that, we clearly need a system to be able to do that, but we can’t be limited to that. We need to add onto that a broader vision that is reaching into a surveillance strategy that is targeting wildlife animals, livestock, and that interface between the animals and people.

“In the case of emerging diseases, we can use that early insight to stop the emergence. We can intervene and prevent an outbreak. We can prevent an epidemic. We can prevent a pandemic.”

So first and foremost, the surveillance system needs to be multi-sectoral. It’s not simply the responsibility or the purview of a Ministry of Health or the World Health Organization. We need to begin removing the stove pipes that isolate our ability to bring together the animal health community, the eco-health community, and the human health community. In that way we can build a robust surveillance system that isn’t just waiting for an event to happen, but that is reaching upstream, is being proactive, and is beginning to give us the insights into what may pose to be a future threat. Again, let’s go back to hurricane forecasting. We don’t just sit in our homes in Miami and wait for a hurricane to happen. We have surveillance systems that are monitoring meteorological events over Ethiopia and watching those meteorological events move across the Sahel and out into the Atlantic Ocean. And we have early insight into which of those meteorological events could evolve into a tropical storm.

The difference now, the big difference, is that we can’t stop hurricanes. As we see them moving across, we can’t prevent them from evolving from a weather pattern over Chad into a tropical storm off the coast of Senegal. In the case of emerging diseases, though, we can use that early insight to stop the emergence. We can intervene and prevent an outbreak. We can prevent an epidemic. We can prevent a pandemic.

Interviewer

Dr. Carroll, this has been a really interesting conversation. And we would really love to stay here all day to hear your insights. For our viewers who would like to know more about your work and what you have accomplished, Netflix has you as the star of a series called “Pandemic: How to prevent an outbreak”. So we want to thank you for your great work, wish you a great day, and please stay safe.

Dr. Dennis Carroll

Thank you, and stay safe as well.

via COVID-19 Africa Watch
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