Using a mathematical model to calculate how immunity to flu changes over a lifetime, scientists have found that most adults only catch the flu twice every decade, according to a Reuters report.
The relative infrequency of the flu in adults means many flu-like illnesses that adults catch are actually caused by other viruses, such as rhinoviruses and coronaviruses.
To better understand how flu infections impact immunity, the team of scientists — made up of researchers from the U.S., Britain and China — analyzed blood samples from adults in Southern China, examining the levels of nine different flu strains that circulated from 1968 to 2009.
The team then compared the levels of antibody in the blood samples with the flu immunity trends produced by their mathematical model.
The findings — which were originally published in the journal PLOS Biology — revealed that while children get the flu nearly every other year, flu infections become less common with age.
Using the results from the study, researchers and drugmakers may be able to better predict how the flu virus will change in the future and how the virus will react to vaccines, according to one of the researchers, Adam Kucharski, PhD.
"What we've done in this study is to analyze how a person's immunity builds up over a lifetime of flu infections," Dr. Kucharski told Reuters. "This ... helps us understand the susceptibility of the population as a whole and how easy it is for new seasonal strains to spread through the population."
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