Would you believe that your flu risk depend on your birth year? Find out here why.
A new study of people in Asia and the Middle East suggests that the year in which you were born may predict your risk of getting some types of the flu.
The study was published in the Journal Science and it was led by a graduate student in ecology and evolutionary biology at the University of California, Los Angeles (UCLA).
In the study, the researchers analyzed data from more than 1,400 people, predominantly living in Asia and the Middle East, who at any point in their lives, had been infected with two strains of the bird flu called H5N1 and H7N9.
Researchers discovered that the people in this study who were born in 1968 or later were less susceptible to a certain strain of the flu compared to those born before 1968. This is because this older population had been more exposed to a similar strain as children.
The study said that the new findings could help researchers predict which age groups are most at-risk for infection and severe illness in future influenza pandemics. In scientific terms, “pandemic” means that an illness is very widespread and infects a lot of people.
The lead study author Katelyn Gostic said, “in the past, we always assumed that when pandemic flu viruses emerge from animals, the human population is an immunological blank slate. In other words, researchers assumed that everyone’s immune system would be defenseless against a new, widespread strain of the flu.”
However, “new results suggest the opposite: that a lot of people might actually be immune against a new strain of flu virus from animals if they were exposed to a similar strain as children.”
Previously, the scientists noted that the age of a person appeared to play a role in determining which virus that individual got during influenza outbreaks. They said that while H5N1 typically affected children and young adults rather than older people, the other virus, H7N9, was found predominantly in older adults.
In the new study, the researchers discovered that the dividing line between the two age groups was 1968, the year of the so-called Hong Kong influenza pandemic.
The virus that caused the Hong Kong flu pandemic replaced other flu viruses from a genetically different virus group that caused most flu cases in the past 50 years.
According to the study, the H7N9 strain of the virus, which was shown to mainly infect older adults, is genetically similar to the Hong Kong flu. It said that older adults who were born before 1968, were not exposed to this type of virus as children.
Older adults, instead, were exposed to the strains of flu that were common before 1968, which are genetically similar to the H5N1 strain. Thus, the study said, that the older adults in the study were more protected against the H5N1 strain.
On the other hand, the study also reveals that people born in 1968 or later may have been exposed to the Hong Kong flu-like H7N9 strain as children. Because of this, they were less likely get sick from this strain and more likely to get sick from the H5N1 strain, because they were not exposed to similar strains as children.