Adults and Flu Frequency

With cold and flu season drawing to an end, you may be breathing a sigh of relief that you didn’t catch anything worse than the sniffles. But this might be due to more than just your vigilant hand washing (although that does help), because the flu may not be quite as prevalent in adults as you have been led to believe. In fact, new research suggests that most of the illnesses that leave you congested and feeling awful are really just colds, since the average man and woman only come down with an influenza infection once every five years.

That’s right. The study, which was conducted through Imperial College London in the United Kingdom, found that otherwise healthy adults typically catch the flu just once every five years or so.¹ Roberts, Michelle. “Adults get flu ‘about once every five years’.” BBC News. 3 March 2015. Accessed 8 March 2015. http://www.bbc.com/news/health-31698038 The subjects were 151 people living in China, ranging in age from 7 to 81. Blood was drawn from each participant and tested for the presence of influenza antibodies, which the body makes after exposure to the virus.

It would be difficult to analyze the blood samples for every single strain of influenza, since there are many variations due to the virus’s ability to mutate regularly. Therefore, the scientists concentrated on nine of the most prevalent strains of flu that have been identified as showing up all over the world from 1968 through 2009. The testing the researchers performed was designed to assess whether a volunteer had at some point been infected with each strain and how often an infection occurred.

Interestingly, the results showed that adults 30 and older generally only experienced influenza infections once every five years, or twice in a decade on average. This was considerably less than what was found in the children involved in the study, who tended to average a flu infection every other year. The research was not intended to offer an explanation as to why the virus was so much more common in children, but it may have to do with closer contact with contagious peers or a lack of protective antibodies to a particular strain. It’s important to keep in mind that having a strong immune system isn’t just about health and nutrition. It’s also about having memory of disease so that your body has a built-in defense. Adults, since they’ve been exposed to more germs during the course of their lives, have more built-in defenses. Of course, the immune systems of senior citizens have even more memories, but the strength of their immune systems is no longer what it once was.

This study is limited by its small and homogeneous population sample. However, since the flu strains the scientists chose to focus on are all known to have circulated internationally, it would make sense that similar findings would likely be uncovered among other adults living in different parts of the world.

The conclusion about the flu’s relative infrequency brings up a couple of issues to consider. The first issue is that many people say they have come down with the flu if they are sick and feeling lousy. But these findings suggest that they probably did not, unless it has been a few years since their last bout with the flu. In other words, it’s important to know the symptoms. While both a cold and the flu cause nasal congestion, sore throat, and a cough, the flu also more commonly induces a fever, extreme exhaustion, and body aches; and the symptoms tend to come on much more rapidly and hit harder.

The second issue to consider is the so-called necessity of getting a flu shot. Many doctors will recommend it for all patients, regardless of their likelihood of exposure or risk of complications. But these vaccines are basically created based on an educated guess as to which strains of the virus will be circulating that year. And many years–including the winter now ending–they get it totally wrong. The flu shot for the winter of 2014-2015 was found by the Centers for Disease Control and Prevention to only be 23 percent effective across all age groups.² Flannery, Brendan; et al. “Early Estimates of Seasonal Influenza Vaccine Effectiveness — United States, January 2015.” Centers for Disease Control and Prevention. 16 January 2015. Accessed 9 March 2015. http://www.cdc.gov/mmwr/preview/mmwrhtml/mm6401a4.htm?s_cid=mm6401a4_w.

Now, with the current study’s results suggesting that most of us are not facing much of a risk most years, it seems more questionable than ever. Plus, there is also the major downside of side effects associated with getting a flu shot, ranging from muscle pain, headaches, and fever to potentially serious allergic reactions and neurological problems. In any case, it’s certainly something to keep in mind if your physician starts pushing you to get a vaccination next fall. And you can better your chances of avoiding the flu by taking a natural anti-pathogen formula at the first sign of symptoms of the virus. If you hit it hard in the incubation phase you can usually prevent it from ever taking hold.