This May Be Why Flu Season Is Worse For Some People, Study Says
With flu season this year starting earlier than normal, we're on the lookout for new knowledge that can help us combat the virus.
But in truth, the flu is more than just one virus, and each year doctors attempt to beat the strain of flu that breaks out as best they can. The many types of flu viruses are a big part of why there's a different flu shot each year.
Scientists at the University of Arizona may have found an answer to one of the more puzzling flu season challenges: why individuals can have different responses to the same strains of the flu.
Thanks to a process called immunological imprinting, some people are better prepared to battle flu if they were exposed as a child.
The researchers used data from the Arizona Department of Health Services to consider the different impacts of first exposure to two of the primary flu strains that have been responsible for outbreaks over the last few decades: H1N1 and H3N2.
A distinct correlation was shown in the results: People who encountered H1N1 as a child were less likely to be hospitalized due to H1N1 later in life, while those who encountered H3N2 at a young age were better protected from that particular strain as they got older.
"In other words, if you were a child and had your first bout of flu in 1955, when the H1N1 but not H3N2 virus was circulating, an infection with H3N2 was much more likely to land you in the hospital than an infection with H1N1 last year, when both strains were circulating," said Michael Worobey, DPhil, head of the Department of Ecology and Evolutionary Biology and a co-author of the study.
Following this discovery, the researchers sought to find out why this pattern exists. Their research showed that H1N1 and H3N2 come from different branches of the "influenza family tree." When we're exposed to a type of flu from one family, research suggests that we are better able to combat that specific strain and also other strains from the family.
"Our immune system often struggles to recognize and defend against closely related strains of seasonal flu, even though these are essentially the genetic sisters and brothers of strains that circulated just a few years ago," says lead author Katelyn Gostic, Ph.D.
Interestingly, it does seem that your body has a specific ability to fight those strains related to your first exposure, and those that come second, or third, our body is less able to recall for protection.
"Whichever subtype our immune system sees first lays down an imprint that protects us especially well against strains of the same subtype," said Worobey, "but relatively poorly against strains from other subtypes, even though you've encountered those subsequently."
This new understanding of how previous exposure affects our future protection will hopefully lead to better knowledge of how each year's flu outbreak will affect different age groups, based on what strains were active earlier in their lives. It may even offer an opportunity for more specific use of the flu vaccines, based on which strains people are naturally more able to fight off.
If you don't want to leave fighting the flu to your immune system's memory, there are some great natural ways you can boost your immunity this season, and some foods may help you kick the cold or flu before it can really take hold.
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