Flu Shot Failure: Here's Why
Influenza, or Flu, is a contagious, respiratory illness caused by influenza viruses that can result in mild to severe illness. The serious outcomes of Flu infection can lead to hospitalization or death.
There are 3 types of Flu viruses (A, B, C). Types A and B are responsible for seasonal epidemics nearly every winter:
· Influenza A viruses are divided into subtypes based on two proteins found on the surface of the virus: hemagglutinin (H) has 18 subtypes, and neuraminidase (N), which has 11 subtypes
· Influenza B viruses are further broken down into lineage and strain
· Type C infections cause mild respiratory illnesses, and are not thought to cause epidemics
The Centers for Disease Control and Prevention (CDC) follow an internationally accepted naming process for influenza viruses (see examples below):
· The antigenic type (A, B, C)
· The host of origin, for example swine or chicken. (For human-origin viruses, no host of origin designation is given)
· Geographical origin
· Strain number
· Year of isolation
· For influenza A viruses, the H and N description. For influenza B, the lineage and strain
The flu vaccine you receive may contains 3 or 4 strains of flu virus, depending on your health needs. Some flu vaccines are specially made for the elderly and those with a weak immune system.
For the influenza season of 2017-2018, the flu vaccine contained:
Three strains (2 influenza A and 1 influenza B)
· A/Michigan/45/2015 (H1N1) virus
· A/Hong Kong/4801/2014 (H3N2) virus
· B/Brisbane/60/2008-like (B/Victoria lineage) virus
· B/Phuket/3073/2013-like (B/Yamagata lineage) virus
The influenza vaccine for 2016-2017 contained:
· A/California/7/2009 (H1N1) virus
· A/Hong Kong/4801/2014 (H3N2)
· B/Brisbane/60/2008-like virus (B/Victoria lineage)
· B/Phuket/3073/2013-like virus (B/Yamagata lineage) (4th strain)
Examples of animal influenza include:
· Dog: A/canine/Guangxi/L1/2013(H3N2)
· Duck: A/duck/Hong Kong/147/77(H9N6)
The flu viruses selected each year for the flu vaccine are based on the findings of 142 influenza centers around the world. These centers research flu virus trends, such as:
· Which flu viruses are circulating
· How the viruses are spreading
· How well current vaccine ingredients are protecting against newly identified viruses
Based on the information gathered, scientists must decide which strains will cause the greatest risk to the U.S. There is no exact formula or finite answer.
Because Flu viruses are constantly changing and mutating, your immune system can’t recognize the Flu virus from year to year. That is why you need to get a new flu vaccine each year.
Even though the Flu vaccine may prove to be ineffective, it is the best defense we have against getting sick with and possibly dying from the Flu.
Learn more about the Flu vaccine in my book, The Practical Patient.