20200520W Santa Cruz, CA: The first article to catch my eye today as I looked back to Dec 19, 2019, is Why your first battle with flu matters most, a article from the University of Arizona about a research paper published online on this same date: Childhood immune imprinting to influenza A shapes birth year-specific risk during seasonal H1N1 and H3N2 epidemics.
The researchers looked at Influenza virus subtypes H1N1 and H3N2 and found that “birth year-specific differences in childhood immune imprinting, not differences in evolutionary rate, explain differences in H1N1 and H3N2’s age-specific impacts.”
A result found by the researches was evidence to support the view that immune protection is stronger when acquired as a child rather than as an adult:
The fact that elderly cohorts show relatively weak immune protection against H3N2, even after living through decades of seasonal exposure to or vaccination against H3N2, suggests that antibody responses acquired in adulthood do not provide the same strength or durability of immune protection as responses primed in childhood.
Another possible conclusion not mentioned is that the H3N2 vaccinations, versus naturally acquired immunity, may partially explain the reduced immune protection in adults.
The University of Arizona article has some interesting quotes:
“Clearly, something compromises the immunity to strains that you see secondarily, even if they belong to the same group as your first exposure,” Worobey adds. “The second subtype you’re exposed to is not able to create an immune response that is as protective and durable as the first.”
In other words, our ability to fight off the flu virus is determined not only by the subtypes we have encountered over the course of our lives, but also by the sequence in which we have encountered them.
“Whichever subtype our immune system sees first lays down an imprint that protects us especially well against strains of the same subtype,” Worobey says, “but relatively poorly against strains from other subtypes, even though you’ve encountered those subsequently.”
The molecular causes of this effect are currently being studied, according to the researchers.
“Part of your immune system’s response to current infection is directed against the strain you first had as a kid, and that investment of fighting the last war appears to compromise your ability to form a fully effective immune response to the invader you encounter later,” Worobey says.
Regarding vaccines, Worobey, one of the researchers, has this to say:
“We need a vaccine that targets the deficits on an individualized level,” Worobey says. “Our work has clearly shown that the first virus we had can have a profound long-term effect. The bad side of that is that our immune system seems to be locked into fighting just one half of flu genetic diversity, and we need to find ways of breaking that.”
This research suggest to me that if we keep SARS-CoV-2 from infecting our children today, then they will be more susceptible to infection from SARS-CoV-2 even decades from now. It also makes sense to me that vaccines should not be the first solution thought of when deciding how to protect the population from a pathogen, and perhaps should be the last solution considered. Instead, the development of anti-virals that can assist the immune system in fighting off a viral pathogen make more sense. This would allow the body to naturally develop an immunity. Also, we need to develop treatments to improve recovery time and protect the body from the long-term effects of a particular viral infection.