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During the 1918-19 outbreak, it was thought that Spanish flu was caused by bacteria rather than a virus.
They learned how to behave differently. It hits proportionately more younger and healthier adults. Experts believe that they have been infected by a common strain and have had a degree of immunity.
Dr. Niall Johnson, who published a study of the 1918-19 pandemic, said that the family was diagnosed with infectious disease, but not at this scale.
Many of the medical memoirs mention the "They said they did not offer that much," he said.
Dr Jonathan D Quick is an expert on epidemics worldwide
"With some flu viruses – it was true in 1918 and in 2009 – one of those things that happens river kills you is not the river itself, "he said. "They want to kill you."
"They did not have antibiotics then, so they died faster. But the other thing that happens, especially in young people when they have a good, active immune system is that their body overreacts. It ends up just filling your lungs with fluid.
Dr. Johnson says the impact of new viruses today will vary, for several reasons 1918-19.
"So, yes, I think we are better placed than in 1918
"One of the most important things is to invest in the so-called universal flu vaccine," he says, "which one works against all strains of the virus, by targeting the part of the virus which does not." t change.
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Why are some river outbreaks worse than others?
The UK government sets out at an official National Risk Register, which says it is not immune to infectious disease from another part of the world.
- Up to half of the UK population could experience symptoms
- This could potentially lead to between 20,000 and 750,000 fatalities and high levels of absence from work.
Dr Quick believes the UK is the only country to report risk in this way.
But globally, are we still complacent?
"Absolutely," he says. "I believe we're just as vulnerable today to big river as we had in 1918 but for different reasons." So today we have four times the population, we are twice as urbanized, and that crowding has been a factor in recent Ebola outbreaks,
"We are 50 times as mobile – so we're in the air, traveling across borders, there's no place on the planet which is more than 24 to 36 hours away from any major city. "
He says flu is tricky, a virus that keeps mutating and exchanging genes.
" With all of those risk factors in play, we could have an epidemic with a new virus that has mutated and that "Do not have any immunity to," he says.
"We could have outweighed which could kill between 200 and 400m in the matter of a couple of years and knock the global economy as bad as the Great Recession."  Image caption
Predicting the path of a pandemic
The BBC Four Pandemic experiment, with mathematicians from Cambridge University, involved nearly 29,000 people downloading an app to track their movements and social interactions to predict how a pandemic might spread.
- 43.3m in the UK could catch influenza in a pandemic, in a worst-case scenario
- The worst case could have been 886,877 deaths over the course of 248 days.
- The virus might spread more
Dr Meirion Evans, a recent retired consultant epidemiologist at Public Health Wales, suspects the key is vigilance and sharing data – underpinned by a global surveillance system which is coordinated by the World Health Organization (WHO).
"If there's an incident, the local specialist laboratory wants to isolate it, to identify it, or if it's not, what virus it is to, "he said.
Technology could help. The news from the Health SARS outbreak has it outstripped itself in China.
We have come a long way from old newspaper adverts, offering cure-all remedies, old wives' tales and simple hope. But there are lessons still to learn – and we underestimate the flow of our peril.
"If anyone does it, humanity has not escaped infectious disease," says Dr Johnson. HIV, multi-drug-resistant TB, flu, Ebola all put to pay for that.
"In the mid-20th century, some people are rather hilariously claiming to be infectious disease
Although it is a rare occurrence, Dr
"There is a need to be vigilant and to open their eyes – because delays are deadly – to respond to the immediate epidemic and then once the panic's gone, keep promises about investing in the next one; it's that leadership. "