Fifty million dead

A century since the worst flu pandemic in history

It's been 100 years since the most devastating flu pandemic in recorded history. The 1918 flu caused the deaths of at least 50 million people – more than the world war one was responsible for – and it was quick; within 27 weeks it had killed more people than HIV killed in 27 years. 

The impact of the 1918 pandemic can arguably, still be felt today. Around the world, thousands of influenza virologists are studying the flu to find out everything they can in an attempt to prevent a repeat of 1918. Dr Kirsty Short is a flu virologist in the science faculty at The University of Queensland, and she focuses her research on reducing the severity of the flu in humans and other animals. 

In December 2017, Digital Content Producer Matthew Taylor recorded Dr Kirsty Short's thoughts on the 1918 flu pandemic and the research happening in the field. 


I think we should always be worried, I think we should always be vigilant, and always be concerned, because everything as history has taught us is that flu pandemics are not only severe, but they're almost inevitable.

There's one very interesting phrase from Indonesia, and I'm not going to say it in Indonesian because I don't speak Indonesian, but it basically translates to sick in the morning, dead by the evening – sick in the evening, dead by the morning.

So the 1918 pandemic is probably what people use to visualise really the worst case flu scenario. This was a really severe pandemic; it did kill about 50 million people worldwide, and you need to put this in perspective. So this killed more people than World War One – this virus killed more people in 27 weeks, than HIV killed in 27 years. This was a really, really severe pandemic, and one of the things that makes this pandemic particularly unusual is that it wasn't just killing the very old or the very young. It was that really, the people who were most severely affected, were those in their immunological prime – so middle-aged adults were particularly susceptible to severe disease. Now, it did affect every country – there was no real country that was protected – but definitely what we know is that mortality rates significantly varied between countries. If we look at sort of the death rate per thousand people we know in Australia that was about 2.7, so 2.7 people per every thousand people died. In France that jumped up to 7.3, so much higher in France, but then when we look at certain countries like South Africa it was about 43, and then if we look at Western Samoa – what's now known as Samoa – it was 236, so 236 people per thousand would die, and that's incredibly high for a flu pandemic. And as you can see obviously, then there were also local factors that were influencing the death rate.

So certainly Australia had a much lower mortality rate than other countries, and that again can be attributed in part to maritime quarantine. So Australia had a quarantine rule implied, and it actually delayed the onset of the virus in Australia. Now, unfortunately, Australia did acquire the virus and basically what happened was that the rules in Australia were that any ship that docked, a doctor needed to go on board and check the health of all the crew and all the passengers before they were allowed to disembark. And unfortunately what happened is the doctor did that, and the doctor actually contracted the virus and then disembarked himself and spread it among the Australian population.

So there are certain things about the 1918 virus that we know made it more severe, and probably a lot of that relates to immune activation. So what seems to have been the case of the 1918 virus is what the virus was able to do: it was able to switch on your immune response. Now normally you would say that's a good thing, right, because your immune response exists to protect you from viral infections but, actually, what seemed to happen in the case of the 1918 virus is it enabled the immune response to be switched on but not switched off again. Your immune response is an incredibly potent component of your body's defences, so it can release all these toxic signalling molecules, everything like that, to actually kill the pathogen but in doing so it also runs the risk of causing tissue damage. This sort of bystander damage, that's at least probably in part what contributed to the severity of the 1918 pandemic, in that there was such an overzealous immune response, but it was not only killing the virus, but it was actually causing lung damage that led to respiratory problems.

So certainly, we know that throughout history there's been a lot of flu outbreaks and flu pandemics. Prior to 1918 there was an 1889 flu pandemic, and that was the Russian flu, certainly that wasn't nearly as severe as the 1918 pandemic, but what I think is actually really interesting is that virus spread pretty much worldwide within four months. Now, when you think about the transport that was available, then there was no, you know, overnight plane to LA or anything like that – so even in the absence of cheap and accessible air travel the virus still spread – I think that's what makes flu particularly alarming in terms of pandemic scenario.

Now after 1918 we've certainly had other flu pandemics. We had the Asian flu in 1957 and then that was followed shortly by the Hong Kong flu outbreak in 68, so they were both pandemics, and these didn't cause nearly as much mortality as the 1918 virus. So the Asian flu was about two million and the Hong Kong flu was probably about one million deaths. But certainly what we've seen throughout history is that flu pandemics occur approximately every 30 years, so if you go from 1968 when you hit the 2000's people are starting to get quite concerned because they knew we were sort of overdue for a flu pandemic and then along came the 2009 swine flu, originally Mexican flu, pandemic. Now initially, I can tell you from a personal perspective when this came out I was a PhD student and I was studying the flu, so I was I was convinced that this was it, this was 1918 all over again, and actually we got incredibly lucky. That virus spread very, very rapidly, so within about a year between 10 to 20 per cent of the world's population was infected but the mortality rate was not very high. So it was certainly more severe than seasonal flu that we get sort of every winter, but it wasn't anything like the 1918 virus. So I think the lesson that we can learn from this is that flu pandemics continue to occur and they always will occur but the severity will be heavily affected by the time in which it occurs and the social factors involved. You know if an outbreak occurs in a context of a war, that's obviously going to be much more severe just because of the disruption to all healthcare services, the reporting, the surveillance things like that. Also I think it really depends on how far we are in advance, in terms of surveillance and preventive measures and everything like that, and that's really where the flu field is looking at going forward

A virologist is anyone who studies viruses. There's obviously lots of different viruses out there, so everyone sort of generally specialises in one virus or another and I specialise in the flu virus. On a day to day basis it's a pretty varied job, I mean, my primary aim is to understand the flu virus in both human and avian populations to ultimately inform pandemic preparedness, and you know, if the next flu pandemic comes I hope that my research will be able to reduce the severity of that.

Flu is a very big research field because it is a big problem, not only for humans but also for poultry population, various animal species. There's a lot of research that people are doing at the moment to try and protect us. Surveillance is a big thing – not only surveying what's going on in terms of the virus infection of human populations but also in animal populations, with that idea that the virus can jump between species – so it's important to know what's going on in both. Another big area of research is vaccination and improving the yearly flu vaccine that we get. This year (2017) in Australia we had a particularly bad flu season and the data that's coming out now is that at least that's caused in part by the vaccine [from] this year not being able to protect against one of the major dominating circulating flu strains. So there are limitations to the current flu vaccine, it does afford only limited protection against a limited number of flu strains and we have to get it updated every year. We're depending on people every year to get flu vaccinated which generally reduces the compliance. So a lot of the research now is looking into doing what's called universal flu vaccinations whereby people are trying to design new vaccines but target more conserved components of the virus, such that it wouldn't provide protection against one flu strain but it would provide protection against all flu strains. In that scenario, even if you had a new virus that jumped into the human population say from birds, that was a completely new sub-type of influenza, this vaccine would theoretically provide protection. So that's obviously that's sort of the goal of flu research, but it's very, very difficult, and it's very difficult because the virus mutates a lot because eliciting a really good immune response is difficult but certainly research like that is very promising for the future.

When we talk about flu in the human population, often the flu pandemics occur when the virus jumps from another animal species – so say avian species into the human population – and that's very hard to prevent and to control. In terms of what the next flu pandemic will be, well that's the million-dollar question isn't it. That's what everybody has been trying to predict. I think there's a few flu strains that are of significant concern, one of which is the H7N9 strain that's currently been causing a lot of problems in China. Now ,this strain was first reported in 2013 and since then it's actually been evolving and it has become more severe for poultry. The few cases of that sort of more evolved or mutated stream infecting humans does seem to suggest that it is getting more severe for humans as well. Now again, we're playing a protection game that we can start stockpiling vaccines and everything for that, but I think the caveat again to that is we don't know 100 per cent that that's going to be the next pandemic. 2009 has taught us that it's very, very difficult to predict; nobody predicted that the H1N1 2009 virus would be the next pandemic, so I think certainly surveillance again plays a big big role in our pandemic preparedness.

There's a lot of hygiene measures that you can take. You know if you cough or you sneeze you should wash your hands immediately because you don't want to then put your hands on somebody else and spread the virus if you're potentially infected. I think the other thing is to really recognise that there is actually a difference between flu and the cold. You know, the flu is actually a much more severe infection than a normal cold and so if you do think you have the flu don't go to work, you know. I know I'm a big one of also believing "I can push through this because I've got deadlines" and everything like that, but at the end of the day you risk infecting your colleagues. In particular, you know, you might have colleagues that have some underlying chronic medical illness that makes flu very severe for them; if you have a colleague who has asthma, who has diabetes, a colleague who's elderly or colleague who's overweight, all these things can actually make flu a very fatal disease, so it's not just about pushing through and getting your work deadlines done – it's also about protecting the people around you.

What fascinates me about infectious disease is that it actually influences the whole course of human history. You know, we often think we are these drivers of our own destiny and I find it incredible that these tiny little viruses that you can't even see with your bare eye can actually shape human history. So I think one very good at example of that, and I don't know how true it is because I think a lot of the evidence is anecdotal, but there have been suggestions that when Woodroe Wilson signed the Treaty of Versailles, he was actually sick at the time. Some people have suggested that it was stroke and that's what caused him to sign what was such a dis-favourable agreement that ultimately lead to World War II, but other people have suggested that, actually, he was suffering from the flu – the 1918 virus – and because that was also associated with some neurological problems, maybe that's what drove him to sign such a poorly-worded treaty and that ultimately gave rise to World War II. Now it's not 100 per cent proven, but if that's the case – I mean how incredible that one little virus could actually shape the whole course of the next century and after because we still feel the effects today.