Responding to pandemic influenza

Published on December 2, 2014   51 min

Other Talks in the Series: Respiratory Infection

0:00
Hello, and welcome to this lecture entitled "Responding To Pandemic Influenza." My name is Jonathan Van-Tam. I'm a Professor of Health Protection at the University of Nottingham. For this lecture, I shall be joined by my colleague from NHS England, Dr. Chloe Sellwood, who will introduce herself in due course. Hello. My name is Dr. Chloe Sellwood, and I'm the Pandemic Influenza Resilience Manager for NHS England. Now, this is the second lecture in a short pandemic series, and it focuses, rather than on what pandemics are, about how, in terms of public health, we respond to them. So it's a good idea to have listened to the first lecture and studied the material to go with it or potentially to have done your own reading about what influenza pandemics are, how they're formed, and their main characteristics. You will really need this kind of background to get the most out of this second lecture.
1:10
To begin with, let's remind ourselves just a little bit about the characteristics of pandemic influenza. Remember that these are repetitive phenomena. But in terms of when they're going to occur, we really just can't predict at all when that will be, and we can't predict how severe they will be. They could be no more severe than a winter epidemic, but they could, on the other hand, be incredibly severe, as was the case in 1918. But we can say that there are recurrent features of influenza A viruses, and as long as we have influenza A in circulation, the possibility of pandemics will always be there. In human history so far, we can only say that the subtypes of influenza A, H1, H2, and H3, are the ones that have caused pandemics, but we simply can't rule out the very large variety of influenza A viruses that exist in the animal kingdom, particularly in the natural reservoir, wild water birds. And if you think about the recent history, you would, like me, be concerned about the potential pandemic threat from H5N1, and also, and very recently, the threat from H7N9 in China. And it's these kind of concerns that drive our continued vigilance and the need to prepare for pandemic influenza and to be ready to respond in an appropriate way.
2:48
So if we're going to deal with pandemic influenza, we need to know a little bit more about what we're likely to be facing. And here, the epidemiology is fairly certain that we are likely to have multiple waves of disease around the world over a period of some 18 to 24 months. We can also be pretty sure that we're going to see an increase in deaths, excess mortality. And we don't know how severe the number of extra deaths will be, but we can say that there will definitely be some. Likewise, in every previous pandemic, the distribution of deaths has moved towards the younger age groups. And again, it's a fairly good planning assumption that we will see more deaths in the younger age groups than we normally see with winter seasonal flu. We will also see quite a high population attack rate. That's the whole proportion of the population who are going to become ill with symptoms, and that is certainly likely to be in the 30% to 35% range, and not any lower than that. And if you put all of that together, then the resultant effects are going to be sustained pressure on health care systems lasting for several months at a time and being repeated for however many pandemic waves there are. And if the pandemic is severe, lots of people are dying, then potentially, wider societal disruption, which we will also have to think about carefully in terms of how we are going to respond.
4:34
It's not a case of if, but when. The quote at the top of this side is from a former chief medical officer in the UK, and refers to the threat of pandemic influenza. A number of features in the modern human and animal world contribute to this. For example, there's increasing urbanization of human populations, which can lead to crowding and pressures on the services that people use, such as food and health services, sewage, and water to name but a few. As we've heard previously, the natural reservoir of potential pandemic viruses is animals, particularly wild water fowl and poultry. Increasing urbanization also means that many populations live very closely with their livestock, both in rearing and in slaughtering. Such close interaction between humans and their animals; for example, in countries in Southeast Asia, offers the opportunity for a new virus to evolve in an animal population, to then cross the species barrier into humans, and spread through a crowded human population. Furthermore, an increasingly mobile global community means that something that starts in one place in the wild can very quickly, potentially within weeks, spread across the globe. Therefore, pandemic preparedness needs to start with a due recognition of the concept of one health, linking animal and human health together. Monitoring animal populations and responding to outbreaks in poultry may help slow the development of a pandemic virus or slow its entrance into humans. The next slides will cover the impact of a pandemic on health in wider society, and then discuss how we can prepare to respond to these impacts.
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Responding to pandemic influenza

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