This winter, three times more people in the UK have died of flu than in the equivalent period last year. In the first week of this year, 5,000 people were hospitalised, and, in recent weeks, flu fatalities have hit a high. But this doesn’t count as an epidemic (a rapid and widespread occurrence of a disease within a community or geographical area) and certainly not a pandemic (the same speed of spreading, but on a global scale). This is just seasonal flu turned a bit nastier than usual.

We could be forgiven for the flu-panic, though. The memory of what the disease can – and did do – looms in history.

The Spanish flu pandemic in 1918 infected around 500 million people worldwide. An estimated 50 million died, including 228,000 people in Britain. Unusually, it disproportionately affected young, healthy adults. Hitting towards the end of the First World War, the virus spread among an already vulnerable population, weakened by food shortages and working together in close quarters. It wreaked havoc. The only part of the world not affected was an isolated part of the Amazon basin.

Although  it was 100 years  ago, hearing  about the  Spanish flu outbreak is still  scary – mainly because it was no super-virus. “When we look at the  1918 strain, there is nothing standout about it,” explains virologist Professor John Oxford of Queen Mary University of London. “We’ve replicated it in mice, grown it in cells in laboratories, and nothing about it immediately jumps out as ‘this is a deadly virus’.”

One possible reason for the devastation caused, particularly in the UK, was young, ill servicemen returning home from the trenches after the First World War ended; as they travelled through train stations and commuter hot spots, the virus soon spread to the suburbs.

That an unremarkable strain can cause such devastation is one of the reasons monitoring flu is a global priority. “Right now there are 120 labs around the world  on the lookout for drifting and changing strains,” says Oxford.  A whole field of expertise has grown up because of the 1918 pandemic. We’ve known since then, says Oxford, that “we can’t sit around and do nothing about the threat”.

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