Influenza (“Flu”) Vaccine

What is the Influenza (“flu”) Vaccine?

Influenza (“flu”) vaccinations are formulated to prevent infection from influenza viruses.  There are three main types of influenza viruses and many subtypes.  Flu season typically runs from late-fall to early-spring and affects approximately 5 – 20% of the U.S. population each year (Flu.Gov).  Influenza Vaccination rates vary from season-to-season, however, statistics from the Centers for Disease Control show that an average of 133.8 million flu vaccine doses were distributed in the U.S. during each of the last three flu seasons.

There are three main (types) of influenza viruses – A, B and C.  These are divided into various sub-types based on two proteins found on the surface of the virus:  Hemagglutnin (H) and Neuroaminidase (N).  It is these surface proteins that contribute to the immune response to the virus.  Most seasonal flu outbreaks are caused by either Influenza A or B.  These flu viruses can cause symptoms, including chills, fever, nasal congestion, sore throat, coughing, headaches, muscles soreness, weakness, fatigue and general discomfort.  Often, these symptoms can be debilitating, requiring several days of bed rest.

The trivalent influenza vaccine is the most common seasonal flu vaccination.  It is designed to protect against three different strains of the virus – two strains of influenza A and one strain of influenza B.  A more recent addition to the flu vaccine market is the relatively new quadrivalent vaccine, which is designed to protect against four strains – two strains each of influenza A and B.  FluMist, the nasal spray version of the vaccine is slightly different in that it contains a live, but weakened version of the virus.

Who should receive the Flu vaccine?

The CDC puts forth recommendations as to who should receive the flu vaccine.  While the CDC recommends that everyone 6 months of age and older should receive a flu vaccine each year, there are a number of exceptions.  There are also a number of contraindications to receiving the flu vaccine.  For example, you should not be vaccinated if you are currently experiencing flu-like symptoms or have previously experienced a severe reaction like Guillain-Barré Syndrome (GBS) after receiving a flu vaccine.  If you have a chicken or egg protein allergy, you should consult with your doctor before receiving a flu vaccination.

How is the Flu Vaccine administered?

Standard needle injection-based influenza vaccines, either trivalent or quadrivalent, contain the virus itself in its inactive state.  When the inactivated virus is injected into your body, your immune system reacts by creating an inflammatory response to defend against it.  Because the inactivated virus does not replicate as the natural virus would, the amount of antigen or virus used is greater.  Your immune system then produces antibodies to the surface antigens (Hemagglutinin and Neuroaminidase), thereby conferring immunity.  Protection from influenza is not conferred instantaneously, but can be delayed days to weeks.

Before receiving a flu shot you should know how it should be administered. The CDC offers guidelines as to how vaccines should be administered. Most flu shots are administered intramuscularly, through the skin, underneath the fatty tissue and into the muscle tissue. All intramuscular flu shots should be injected at a 90-degree angle into the deltoid muscle – which is the upper arm. If an intramuscular flu shot is injected incorrectly, it can result in a serious shoulder injury.

There is only one type of flu vaccine that can be administered intradermally: Fluzone Intradermal by Sanofi Pasteur. This shot should be administered at a 45 degree angle into the subcutaneous tissue by pinching the fatty tissue of the arm together with two fingers.

Intranasal flu vaccines should be administered by having the recipient tilt their head back at a 45-degree angle so that the vaccine can be sprayed into the recipient’s nostril.

The CDC does not recommend administration of the intranasal flu vaccine for the 2016-2017 flu season.

Flu Vaccine Related Links:
Seasonal Flu Information (Flu.Gov).
CDC Seasonal Influenza Vaccine & Total Doses Distributed
1918-1919 “Spanish” Influenza pandemic
Types of influenza viruses
trivalent influenza vaccine
quadrivalent vaccine
FDA – The ultimate authority over the specific vaccine formula sold
2012-2013 flu season
Viruses change – antigenic drift & antigenic shift.
International Federation of Pharmaceutical Manufacturers & Associations.
Dr. Ernest Goodpasture and the Mass Production of Vaccines
How Influenza (Flu) Vaccines Are Made
Flu Vaccine registered trademarks.
CDC Vaccine Administration Guidelines

Vaccine Packet Inserts:
AFLURIA – Trivalent Influenza Vaccine Packet Insert
AGRIFLU – Trivalent Influenza Vaccine Packet Insert
FLUBLOK – Trivalent Influenza Vaccine Packet Insert
FLUCELVAX – Trivalent Influenza Vaccine Packet Insert
FLUARIX – Trivalent Influenza Vaccine Packet Insert
FLULAVAL Trivalent Influenza Vaccine Packet Insert
FLUVIRIN – Trivalent Influenza Vaccine Packet Insert
FLUZONE – Trivalent Influenza Vaccine Packet Insert
FLUZONE – High Dose Trivalent Influenza Vaccine Packet Insert
FLUZONE – High Dose Intradermal Trivalent Influenza Vaccine Insert
FLUARIX – Quadrivalent Influenza Vaccine Packet Insert
FLUMIST- Quadrivalent Influenza Vaccine Packet Insert
FLUZONE – Quadrivalent Influenza Vaccine Packet Insert