Study says year of birth impacts vulnerability to the flu
In influenza research circles there is a concept known as antigenic imprinting, referring to the idea that the type of flu you are exposed to at an early age impacts your immune system's response to the virus for the rest of your days. A new study is adding weight to this hypothesis, with the researchers taking advantage of a rare flu season to uncover rapid shifts in infection trends that appear associated with a patient's age.
The two sub-types of influenza A virus that cause the coughing, aching and fever most are familiar with typically take it in turns, with one circulating one season and the other taking the next. But the 2018/2019 flu season was an anomaly, in that both subtypes, H1N1 and H3N2, took hold at different points in the season.
For influenza researchers at McMaster University, this presented a rare opportunity to delve deeper into the notion of antigenic imprinting. The scientists gathered data from this unusual 2018/2019 flu season and investigated the relationship between a person's age, and therefore the subtype they were likely first exposed to, and their vulnerability to either H1N1 or H3N2.
“We already knew from our previous studies that susceptibility to specific influenza subtypes could be associated with year of birth," says Alain Gagnon from the University of Montreal, lead author of the study. "This new study goes much further in support of antigenic imprinting. Instead of just showing how specific age patterns are associated with one subtype or the other during a single influenza season, we took advantage of a unique ‘natural experiment’ to show how the change in subtype dominance during one season appears to lead, practically in real time, to a change in susceptibility by age."
This immediate shift in vulnerability within the one flu season, seemingly guided by age, could prove valuable for public health officials preparing for epidemics by helping them determine which demographics are most at risk, depending on which sub-type is circulating.
“People’s prior immunity to viruses like flu, or even coronavirus, can have a tremendous impact on their risk of becoming ill during subsequent epidemics and pandemics,” says Matthew Miller, a co-author. “Understanding how their prior immunity either leaves them protected or susceptible is really important for helping us to identify the populations who are most at risk during seasonal epidemics and new outbreaks."
The research was published in the journal Clinical Infectious Diseases.
Source: McMaster University