People contract flu worse others - Why do some people get a flu worse than others explored in the study?

Scientists believe that some people suffer from flu symptoms worse than others because of the first strain they encounter as a child.

The differences are narrowed down to what is called immunological printing, the authors of an article in the journal PLOS Pathogens explained. This is where the subtypes of influenza a person encounters in childhood have a lifelong effect on the immune system's memory and their ability to protect themselves against the virus in the future. The influenza virus is very changeable, so one year's flu vaccine will not work the next.

On the one hand, immunological printing is useful because it protects against certain strains of the flu, "but perhaps at the expense of an equally strong protection against the variants later in life," wrote the scientists.

People contract flu worse others

To conduct their study, the researchers analyzed data from 9,510 relatively severe cases of seasonal H1N1 and H3N2 collected by the Arizona Department of Health Services (ADHS). H1N1 and H3N2 are subtypes of viruses, which have caused severe outbreaks since the 1970's, the authors noted. By looking at the dataset, which detailed how much the flu was affecting people of different ages, scientists expected to shed light on the effects of fingerprints.

They found that H1N1 and H3N2 are from different branches of the influenza family tree. Then, while being infected with a subtype might help to some extent protect the other, the body would be better equipped to fight a strain on a previously found group, the researchers concluded.

Co-author Michael Worobey, of the University of Arizona's Department of Ecology and Evolutionary Biology, said in a statement, "Part of your immune system's response to the current infection goes against the strain it had when it was small, and this reversal of shuffling in the last war seems to jeopardize your ability to form a fully effective immune response to the invader you meet later. "

The reduction in numbers also revealed that those with H2N2 as a child did not appear to be better at fighting H1N1, despite being members of the same influenza family. The team thinks this could be because the order in which we decrypt subtypes could affect our ability to fight the virus.

Lead author Katelyn Gostic, who conducted this research as a doctoral student at the University of California, Los Angeles, said in a statement: "Our immune system often struggles to recognize and defend itself. of closely related seasonal influenza strains, though These are essentially the genetic brothers and sisters of the strains that circulated only a few years ago.

"This is puzzling because our research on bird flu shows that deep in our immune memory, we have a certain ability to recognize and defend against third genetic cousins ​​far from the strains we saw as children," he said.

Worobey said, "Clearly, one thing compromises immunity to the strains you see secondarily, even if they belong to the same group as your first exposure.

"The second subtype to which it is exposed cannot create an immune response that is as protective and lasting as the first.

"In other words, if you were a child and you had your first outbreak of the flu in 1955, with H1N1 virus circulating but not H3N2, you were much more likely to be hospitalized with an H3N2 infection. H1N1 for the last time year, when the two strains were circulating, "he explained.

The authors acknowledged that their study had limitations, including that relatively severe cases involving physician visits are more likely to be detected and included in the data than mild cases. This means that they were unable to determine the relationship between print and mild cases.

However, they believe their results still have implications for long-term projections of how seasonal flu will affect the elderly, who are most affected by flu-related deaths and complications. According to the team, their print status will change over time as people born during the circulation of different subtypes grow.

They also envision work that helps develop flu vaccines, said Gostic.

"We hope that by studying the differences in bird flu immunity, where our immune system shows a natural ability to deploy widely effective protection, and against seasonal flu, where our immune system appears to have bigger blind spots. , power.