Apparently influenza A flus come in two main varieties, the H1 and the H7. When you had your first flu when you were young you got good defenses against that subfamily according to researchers from the University of Arizona and UCLA. This explains why sometimes old and sick people can weather an influenza better than young and healthy people. This insight might have important implications in case of a pandemic.
The research team studied two avian-origin influenza A ("bird flu") viruses, H5N1 and H7N9, each of which already has caused hundreds of spillover cases of severe illness or death in humans. Both strains are of global concern because they might at some point gain mutations that allow them not only to readily jump from birds into humans, but also spread rapidly between human hosts.
Analyzing data from every known case of severe illness or death from influenza caused by these two strains, the researchers discovered that whichever human influenza strain a person happened to be exposed to during his or her first infection with flu virus as a child determines which novel, avian-origin flu strains they would be protected against in a future infection. This effect of "immunological imprinting" appears to be exclusively dependent on the very first exposure to flu virus encountered in life — and difficult to reverse.
[...] In their latest paper, Worobey and co-authors not only show that there is a 75 percent protection rate against severe disease and 80 percent protection rate against death if patients had been exposed to a matched virus as children, but also that one can take that information and make predictions about H5N1, H7N9 and other potential causes of future pandemics.
"If either of these viruses were to successfully jump from birds into humans, we now know something about the age groups that they would be hit the hardest," Worobey said, adding that efforts to develop a universal flu vaccine hinge on such insights because "such a vaccine would likely target the same conserved protein motifs on the virus surface that underlie this age-specific pattern."
https://uanews.arizona.edu/story/birth-year-predicts-odds-if-flu-pandemic-were-strike
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Despite push for a universal flu vaccine, the 'holy grail' stays out of reach
It is the holy grail of influenza science: a universal flu vaccine that could provide protection against virtually all strains instead of a select few. A burst of recent headlines have suggested that we might get one soon. Just last week, the National Institute of Allergy and Infectious Diseases released a strategic plan for the development of a universal flu vaccine, prompting the White House science office to proclaim on Twitter that the goal is "closer than ever."
Experts, however, say we're really not there yet. And to be honest, we can't necessarily even see there from here. "I don't think we're that close at all," Michael Osterholm, director of the University of Minnesota's Center for Infectious Diseases Research and Policy. "I think the kind of work that's gone on has been critical and important, but it's only the first 5 feet of what would need to be a 100-foot rope."
There's no doubt that there is some momentum. The release of the strategic plan — which outlines for scientists the research that NIAID sees as critical and that it would be willing to help finance — signals renewed interest in the quest for a universal vaccine. So, too, does a bill — introduced by Sen. Edward Markey, a Democrat from Massachusetts — calling for $1 billion in government spending for the project.
Previously: Progress Reported on Universal Flu Vaccines
Related: Susceptibility to a Flu Determined by Your Very First Virus Encounter
(Score: 0, Offtopic) by Anonymous Coward on Sunday November 13 2016, @05:46PM
But if you were first infected with a virus from the 'blue lollipop' group as kid, that won't protect you against this novel, 'orange' strain."
(Score: 2) by Entropy on Sunday November 13 2016, @06:41PM
I wonder if this means you have improved immunity to neither?
(Score: 2) by Reziac on Monday November 14 2016, @03:55AM
Shouldn't make a difference. A vaccine is basically a virus that's been hit on the head, or killed, to make it non-infective. The proteins that trigger immune response don't change.
And there is no Alkibiades to come back and save us from ourselves.
(Score: 2) by ledow on Sunday November 13 2016, @07:15PM
Being ill as a child is necessary to not be ill later.
News at 11, people.
(Score: 0) by Anonymous Coward on Sunday November 13 2016, @07:32PM
Exactly. I let my kids play in the dirt, get sick from others, etc. It sounds like bad parenting, but it builds their immune system early in life. They very rarely get sick now that they're grown up, unlike other parents that keep their kids in a sterile environment and wonder why they get sick so often.