A new British study finds that the typical person over 30 only gets the flu about twice every decade.
“For adults, we found that influenza infection is actually much less common that some people think,” said study senior author Dr. Steven Riley, of Imperial College London. His team published its findings March 3 in the journal PLoS Biology.
“In childhood and adolescence, it’s much more common, possibly because we mix more with other people,” Riley said in a journal release. For adults over 30, “the exact frequency of infection will vary depending on background levels of flu and vaccination,” he added.
The study team analyzed blood samples from volunteers in southern China to assess their levels of antibodies against nine different flu strains that circulated there between 1968 and 2009.
“This is the first time anyone has reconstructed a group’s history of infection from modern-day blood samples,” said Dr. Adam Kucharski, who worked on the study at Imperial College London.
From the blood test results, the investigators concluded that children get the flu an average of every other year, but that flu infections become less frequent as people move through childhood and early adulthood.
“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,” Kucharski noted. Even though people may think they have influenza, “symptoms could sometimes be caused by common cold viruses, such as rhinovirus or coronavirus.”
On the other hand, flu can sometimes be milder than many people realize. “Some people might not realize they had flu, but the infection will show up when a blood sample is subsequently tested,” Kucharski said.
The researchers also developed a model of how people’s immune systems change over a lifetime as they encounter different flu strains. The model adds to evidence from previous studies that the flu strains people are exposed to earlier in life trigger a stronger immune reaction than those encountered at later ages.
Add this information to the latest studies showing this year’s flu vaccine has an effective preventative rate of about 13%. (Previous studies had rated it at about 23%)
So make sure you get your ineffective flu shot every year to possibly, but not probably prevent an infection that you might otherwise contract about once every 5 years.
Just ignore the fact that the shot is modifying “how people’s immune systems change over a lifetime as they encounter different flu strains.” We have no idea what the long term effects of flu shots will have on the immune systems of our population. However, we are all too aware of the negative effects of antibiotics on the immune system with the rise of MRSA and C. difficile.
While we focus on the minimal potential threat in this country from the Ebola virus, we ignore the very real threat that we are creating a much more serious potential epidemic from altering our body’s natural immune response to infection.
Just look at the blogs I have written on this subject this year:
C. difficile Infected Almost Half a Million in Single Year – March 6, 2015
Change in Gut Bacteria May Precede Type 1 Diabetes in Kids – February 20, 2015
Only 23% Protection From This Year’s Flu Vaccine – January 23, 2015
If you check my last blog of 2014 on December 29, you will find four additional blogs related to this issue.
The Bottom Line:
You must truly assess your risk factors and those of the entire population prior to getting a flu shot. For me, the risks associated with the shot are much higher than my risk of contracting the flu.
March 3, 2015 National Institutes of Health