Professor Steven Riley talks about flu pandemics and the work of the MRC Centre for Outbreak Analysis & Modelling, Imperial College London.

Ask someone to name the event that caused the greatest loss of human life in the last 100 years, and they’ll probably answer WWII. But they’d probably be wrong.

21 years before the war broke out, just as WWI was coming to an end, a flu pandemic swept the globe with a ferocity not seen since. Recent estimates suggest that as many as one in three people on the planet were infected, and between 50 and 100 million died.

The 1918 flu pandemic – commonly referred to as Spanish Flu – whilst largely absent from the public conscience, still haunts security and flu experts alike.

I caught up with Dr Steven Riley, Professor of Infectious Disease Dynamics in the MRC Centre for Outbreak Analysis & Modelling, to talk about pandemics, biosecurity and his work at Imperial College.

Was there something special about the 1918 outbreak that made it so deadly?

The 1918-1919 strain certainly had a higher fatality rate than anything we’ve seen recently. The last influenza pandemic was in 2009, which killed about 1 in 10,000 infected individuals, so it was 100x less deadly.

But it’s very hard to say with certainty if this was mostly due to the virus or the conditions of the world at that time.

One thought experiment we play is to imagine what would have happened if the 1918 virus came in 2009. Our medical understanding and infrastructure is certainly better than in 1918, but there’s no doubt it would still have been an enormous event.

How much of a security threat do pandemics pose?

It’s extremely difficult to say if and when a pandemic might occur. However, it’s clear that the consequences of such an event are potentially huge, and so it’s certainly something to take seriously.

Is it possible to anticipate which viruses have the potential to become pandemic?

Some characteristics of viruses do give indications of their pandemic potential. For example, if they have previously shown to infect humans or not. Researchers are aware of animal populations that act as reservoirs for infectious diseases that could spill over to humans.

Those that are found in many geographic locations and in close proximity to humans are the most likely to be a problem. Birds would be a good example of this. 

What goes on at the MRC Centre for Outbreak Analysis & Modelling?

We are one of the largest research centres in the world working on the epidemiological analysis and modelling of infectious diseases. Our team is very interdisciplinary, with expertise spanning statistics, mathematical modelling, epidemiology, genetics, intervention science and health economics.

Our research can be divided into six themes: Global Health; Vaccine and intervention research; Emerging infections and outbreak response; statistics and modelling methodology; Health systems and health economics; and Ecology, evolution and genetics.

I understand that members of the MRC centre worked on the response to the Ebola crisis?

Yes, that’s right. A big part of the work of the Centre is to work closely with health organisations, such as the World Health Organisation, on policy during an outbreak. 

We receive information from the site of the outbreak and work to understand the dynamics of the disease, and help public health organisations develop policy for action. We had a large team of dedicated researchers during the Ebola pandemic. It can be a very intense time given the importance of speed and accuracy.

What information do you receive and how do you use it?

Field epidemiologists survey people in the outbreak area and send the data to a few groups around the world, including us, sometimes via intermediaries such as the WHO.

Some of our core skills are in mathematical modelling and statistics, which allow us to use the survey information to infer the dynamics of the infection.One of the most important inferences is the incubation period; the time it takes to develop symptoms after exposure.

This is extremely valuable as it drives policy on how long people have to be observed, and how quickly the infection moves.

Can you recommend any sources of further information on these topics?

Our website has further reading on our work, including links to academic publications.

Outside of Imperial College, there’s a great free MOOC from the London School of Hygiene and Tropical Medicine on the Ebola crisis. This covers a range of subjects including disease modelling and how this drives policy. 

Finally, if you’re interested in the 1918 flu pandemic, you might be interested in the non-fiction Pale Rider, published earlier in 2017. There’s a good review from The Guardian here.

Dr Steven Riley is Professor of Infectious Disease Dynamics in the MRC Centre for Outbreak Analysis & Modelling, Imperial College London.