Inactivated Influenza Vaccine (Flu Shot): The inactivated influenza vaccine is given to prevent influenza infections. Influenza is not a mere cold. Influenza is a highly contagious respiratory illness with respiratory symptoms that can range from mild to severe, even at times leading to death. Flu symptoms comes on suddenly after a short 1 to 3 day incubation period. See the section on Influenza in this handbook for a description of the illness.

Genetic material in influenza viruses is known to slightly change, merge with other influenza virus genetic information, re-assort or even mutate periodically.  Because of this, people who have had the flu or the flu vaccine in the past can be susceptible to influenza infection with a type of influenza which has changed its genetic makeup.  This ability of the virus to change its genetic makeup causes the immune system of the body not to recognize the virus as an infection which the body has fought off in the past. This leads to periodic flu epidemics and is reason that yearly flu shots are recommended. Each year different strains of influenza are placed in the flu shot. This is to cover the expected influenza strains that will circulate each year. The immunity of the flu shot is not lost each year. You get a flu shot yearly, to protect against new strains of the flu that are hopefully are included in the new vaccine for the year. Each flu shot boosts your immunity to the flu.

In 2009, the H1N1 influenza virus strain re-emerged in humans causing great concern among flu experts. Some history is in order to understand the magnitude of the concern. In March, 1918 a new strain of influenza began to spread in the world’s population.  Unlike previous strains of the flu, this strain quickly became a worldwide health emergency because of the severity of infection. H1N1 influenza infection caused many people, including healthy young adults, to develop severe respiratory symptoms including bleeding from the lungs. This led to many flu cases which were fatal. The “Spanish Flu” lasted from March 1918 to June 1920.  It is estimated that 50 to 100 million people were killed worldwide.  An estimated 500 million people, one third of the world’s population (approximately 1.6 billion at the time), became infected. Before it was over 18 months later, an estimated 675,000 Americans died of influenza during the pandemic. Of the U.S. soldiers who died in Europe during world war I, half of them fell to the influenza virus and not to the enemy. An estimated 43,000 servicemen mobilized for WWI died of influenza. 1918 would go down as unforgettable year of suffering and death due to influenza. Significant research has been done in the 98 years since the pandemic began. Studies in Alaska done on frozen corpses who died from the flu in 1918 were able to identify the genetics of the influenza virus responsible for the outbreak.  It was H1N1. Ever since this “worst medical holocaust” in history, physicians and health scientists have worried about when the next influenza “super-bug” would re-appear.

Although the 2009 Swine Flu (Novel H1N1) pandemic did pose some risk, it turned out to be nothing like the 1918 disaster.  It had a severity only a little worse than the usual yearly seasonal influenza outbreaks. However, the seasonal flu infections we have each year are dangerous enough. The CDC estimates that between 3,000 to 49,000 Americans die of the flu each year, depending on the severity of the flu for that particular year. By comparison, about 32,000 people die of auto crashes in the US each year.  Therefore, the flu is a major health hazard and flu immunizations are given to prevent this loss of life.

At our clinic we give the mercury free quadrivalent (4 strain) flu vaccine to our patients.  Each year since 2010, the flu vaccine contains the deadly H1N1 strain which gives immunity to it as well as three other strains which flu experts expect to circulate that year. Side effects of the flu shot are generally mild fever and mild soreness of the injection site.  All children aged 6 months and older should receive a flu shot.  If your child is less than 8 years of age and this is the first year your child will receive the vaccine, two doses are required, one month apart. Flu Mist (live attenuated flu vaccine) which was administered in the nose in the past, has been taken off of the market due to ineffectiveness.  It is no longer available.

Bottom line:  You should get a yearly flu shot for you and your family. It can save your life and your child’s life.  It’s important!

Who Should Not Get a Flu Vaccine?

A flu vaccine may be contraindicated in some people, these include:

  • people who have had a severe allergic reaction to a prior influenza vaccine or one of its components
  • people who developed Guillain-Barre syndrome within 6 weeks of getting a previous flu vaccine
  • children under 6 months of age
  • people who have a moderate or severe illness with a fever should wait to get a flu vaccine until the illness is resolved

View the CDC vaccine information sheet on the inactivated flu vaccine here:  vis-flu.pdf