The year you were born could decide whether you survive a big flu pandemic, according to latest research.
The last major flu outbreak in the world killed some 50 million people across the globe in 1918.
And, now scientists have determined that the year a person is born could affect their chances of living or dying when the next big pandemic hits.
Worrying new strains of flu have jumped from animals to humans from time to time. There have, for example, been virulent strains of the disease in pigs and chickens, which have caused huge concern.
Protection zones have been set up in the last week after reports of bird flu in Germany, Austria and Hungary, and infected birds have been killed.
However, generally, deadly strains of the virus tend to evolve and become less serious. While today’s human flu can present a threat to some, particularly the very old and very young and those already vulnerable, it is a much milder version of flu from days gone by.
Now, a new study, which is published in the respected journal Science, has revealed that the flu strain people first get when they are children has a huge part to play in developing their immune system.
They will then be predisposed to fight against one of just two main types of flu.
Professor Michael Worobey, head of Arizona University’s Department of Ecology and Evolutionary Biology, said: “In a way it’s a good-news, bad-news story.”
He said that a person’s first flu infection set them up for either success or failure when it came to fighting future strains of flu.
He added: “The bad news is the very same imprinting that provides such great protection may be difficult to alter with vaccines.
“A good universal vaccine should provide protection where you lack it most, but the epidemiological data suggest we may be locked into strong protection against just half of the family tree of flu strains.”
When someone gets flu, their immune system produces antibodies designed to target a protein which sticks out from the flu virus.
While there are a number of different proteins, researchers say they really only fall into two main categories.
People born before the 1960s tended to be exposed to a different strain than those born in later years.
So, even though the elderly are usually thought to be most at risk of flu, it could be that they are protected more than younger people if the next big pandemic happens to be one they have immunity to.