How Often We Actually Catch The Flu

A new study reveals how often we really get sick. (Photo: Getty Images)

Think about it: When’s the last time you really, truly were knocked down with the flu?

According to a small new study, if you’re over the age of 30, you’ve probably only caught it twice a decade.

The research, published in the journal PLOS Biology, shows that the frequency at which people are infected with the flu goes way down as people get older. While kids examined in the study became infected with the flu every other year, on average, people age 30 and older seemed to only get sick with the virus twice a decade.

The study involved analyzing blood samples from 151 volunteers in Southern China; researchers looked specifically at levels of antibodies against nine influenza strains that circulated over approximately 40 years.

You might say to yourself: “But I’ve definitely been sick more than twice in the last 10 years!” Sure, that’s probably true — but it’s important to remember that a lot of other pathogens can cause symptoms that make it seem like you have the flu, when you really don’t.

Related: How To Stay Well In A Room Full Of Sick People

"There’s a lot of debate in the field as to how often people get flu, as opposed to flu-like illness caused by something else. These symptoms could sometimes be caused by common cold viruses, such as rhinovirus or coronavirus,” study researcher Adam J. Kucharski, MMath, PhD, an infectious diseases expert at the London School of Hygiene & Tropical Medicine, said in a statement. “Also, some people might not realise they had flu, but the infection will show up when a blood sample is subsequently tested.”

That’s what makes this study unique, said Kucharski, who worked on the study while at Imperial College London. “This is the first time anyone has reconstructed a group’s history of infection from modern-day blood samples,” he said in the statement.

The researchers noted a possible reason for the lower frequency of flu infection with higher age in the study: “It has been suggested that influenza transmission is driven by intense social contacts among younger age groups,” the study said. “The decline in frequency of infection with age may be the result of age-specific differences in social behavior.”

Related: Got The Flu? Here’s When To Head To The ER

In addition to the frequency findings, researchers also found that immune response to particular strains of influenza virus is stronger when encountered earlier in life, as opposed to later in life.

The new study has some limitations, the researchers noted, such as the sample population — because the study was only conducted in a small number of people in China, “it would therefore be helpful to test similar models of serodynamics against observed titres in other populations,” the researchers write. Plus, the researchers focused only on A(H3N2) influenza strains for the study, and not group 1 influenza viruses, like A(H1N1). 

Ultimately, it’s important to keep the immune system strong to avoid getting sick. Making sure your hands are washed, getting plenty of rest, and keeping stress levels down are all preventive measures you can take to keep colds and flu at bay. Doctors also recommend getting a flu shot, though this season’s flu vaccine effectiveness is quite low — 18 percent — against the dominant strain circulating this year in the U.S. 

Up Next: Go On, Take A Nap — It’s Good For Your Immune System