Many experts believe the majority of what you learn and who you are is established by age three. Yes, that toddler of yours who’s eating crayons and throwing tantrums in Target – that’s pretty much who he’ll be at 40.
Of course, this is an exaggeration, but there are certainly reasons they call this time period the “developmental years.”
Illnesses during the developmental years work in much the same way. In fact, which flu strand a child gets first also has a lot to do with how they fair as an adult.
Whether your first viral illness was at 5 months or 5 years, the specific strand you contracted will most likely impact how well your body responds to a flu pandemic.
Referred to as “imprinting”, the first virus a person catches shapes their immune response to prepare for other strains encountered later on in life. If our body were a house, imprinting would be the blueprints and the virus would be the pen that drew them.
According to Newsweek, imprinting works much like how vaccines work: When your body is exposed to a certain strain of infection, your autoimmune system responds by building antibodies that protect your system from further infection from that specific strain. However, the first infection you are ever exposed to holds a specific – and very special – status in your body.
This recent flu season, baby boomers were hit particularly hard, and that may not be a coincidence, according to Dr. Dan Jernigan, director of the influenza division of the Centers for Disease Control and Prevention’s National Center for Immunization and Respiratory.
During past flu seasons, the rate at which toddlers and infants were hospitalized for the flu corresponded with the same rate of adults, aged 50 to 64. But this year, the flu hit the baby boomers pretty hard – rates surpassing those of their grandchildren. And that probably isn’t coincidental.
The phenomenon known as imprinting generally protects us by helping the immune system react more quickly to new virus strains: either attacking the virus quicker, subjecting us to more mild symptoms or completely safeguarding us against them.
How does this work? If the hemagglutinin (a protein marker found on the molecule) of a current, active virus matches the imprint of a similar hemagglutinin you encountered in prior strains, then the immune system may produce antibodies in response to the new infection, simply by detecting that protein.
But, if almost everyone is exposed to a version of the flu at some point in their life, why are the baby boomers at a disadvantage? One theory is that an occurrence in 1968 led to a generation of overly-susceptible adults.
The United States flu pandemic of 1968 was the first occurrence in recent time that a viral outbreak was marked by a protein called H3. So, if you are over the age of 50, you most likely were not imprinted with the H3 protein detected in viral strains in subsequent years following 1968.
Because this year’s influenza has an H3 marker, the baby-boomer immune system is less prepared to fight back than those who likely were imprinted with the H3 strain.
Hemagglutinin proteins are separated into two categories: One group includes the H1, H2, and H5 proteins; the other includes H3 and H7. The H1N1 and H3N2 viral strains are most commonly found in North America.
In 2016, an article surfaced by researchers, James Lloyd-Smith and Michael Worobey, showing a correlation between the type of virus a person was first exposed to and how their immune system responded to “bird flu” strains, which more often than not include H5 and H7 molecules. This link was easier to come by due to the rarity of the bird flu virus.
However, with more common viruses like the typical flu, extracting verifiable links between imprinting and seasonal flues can be a bit more tricky. Specific data can be hard to come by due to variables such as the severity of a flu case, the strain involved, and the year the person was born.
But many experts suspect a link between a lack of exposure to the H3 protein and the rise of people aged 50-64 being particularly sick this season.
What’s particularly interesting to note is, while the current influenza is bad, the flu of 1968 was described as being relatively mild. Why? Probably because those 50+ year-olds has been imprinted during a viral pandemic in 1918 that – you guessed it – contained the H3 marker.
The research and data are not conclusive, but it’s a start and may lend itself to tests that determine people’s imprints and the creation of more vaccines to mimic certain hemagglutinin structures.