It's that time again. Flu season. And with it, a constant barrage of reminders to get your annual flu shot. Interestingly enough, what you're being told about the influenza vaccine's effectiveness and the reality are two very different stories. In January 2015, U.S. government officials admitted that, in most years, flu shots are — at best — 50 to 60 percent effective at preventing lab confirmed type A or B influenza requiring medical care.1
At the end of that same year, a Centers for Disease Control and Prevention (CDC) analysis2 of flu vaccine effectiveness revealed that, between 2005 and 2015, the influenza vaccine was actually less than 50 percent effective more than half of the time. I wonder if the reality might be even worse than that.
Research from 2011 shows just how easy it is to inflate efficacy rates simply by using different end points.3 At that time, they found that by using serologic measures, i.e., the increase in influenza antibodies identified in the blood, results in an overestimation of vaccine efficacy.
During the 2015/2016 flu season, FluMist, the live virus nasal spray that typically has been recommended for children in recent years, had a failure rate of 97 percent.4 Its failure was so epic, the Advisory Committee on Immunization Practices recommended FluMist be taken off the list of recommended flu vaccines for the 2016-2017 season, a recommendation CDC officials ended up heeding. There are many other examples of the influenza vaccine not protecting people as promised. So, what might we expect from the vaccine this year?
2017 Flu Vaccine Lineup
Flu vaccines are by their nature a tricky business because influenza viruses are constantly evolving and public health officials have to guess at least six months before the flu season starts which type A and B influenza virus strains will be predominantly in circulation so drug companies can manufacture the vaccines. When the strains chosen do not match the strains actually causing most of the disease in any given flu season, the vaccine's failure rate significantly increases.
Even when there's a good match, the flu vaccine's effectiveness is estimated to be between 40 and 60 percent,5 meaning that, at best, public health officials believe you have a 60 percent lower chance of not getting sick with influenza if you get a flu shot. But it could be as low as 40 percent. Put another way, it is still a coin toss no matter which way you look at it.