Vaccination is the most effective way to prevent influenza illness and associated complications. For the CDC SUMMARY of Prevention and Control of Influenza with Vaccines 2017–18 Influenza Season.

Annual influenza vaccination is associated with a reduction in influenza-related respiratory illness and physician visits. Hospitalizations and deaths among high risk persons are reduced by annual vaccination. Influenza vaccination has also proven effective in reducing otitis media in children and absenteeism in working adults.

Every year the CDC and the World Heath Organization select influenza A and influenza B strains that have the highest probability of causing a pandemic in the upcoming flu season. These virus strains are then used by vaccine manufacturers to produce the annual vaccine. When the seasonal vaccine is well matched with the actual reassorted strains in circulation, a high inoculation rate can induce herd immunity and limit the spread of epidemics.

The CDC web site identifies: trade name, route, package dosage, age appropriate approved influenza vaccines, single pre-filled syringe of multi-use vial packaging in the following table: Influenza vaccines — United States, 2017–18 influenza season

Virus strains included in the 2017–18 U.S. vaccines

All IIVs contain hemagglutinin (HA) from inactivated virus (killed virus) incapable of replication. The HA is derived from influenza viruses antigenically identical to those recommended for a specific season by the FDA.

IIVs are delivered via intramuscular (IM) needle injection or prefilled intradermal micro-injection afterwhich the immune system responds by making antibodies to the viral HA.

An intradermal quadrilent IIV is available. It is given into the dermal layer of the skin via a single-dose, prefilled microinjection syringe and that contains less antigen than the intramuscular IIV formulations. The intradermal vaccine was approved for use in people 18 through 64 years of age in 2017-2018.

Live-Attenuated Influenza Vaccine (LAIV) is not recommended for the 2017–18 season, but it is being recommended for the 2018-19 influenza season. On February 21, 2018, Advisory Committee on Immunization Practices (ACIP) recommended that LAIV4 be an option for influenza vaccination of persons for whom it is appropriate for the 2018–19 season. Quadrivalent LAIVs contain two strains of Influenza A and two strains of Influenza B attenuated virus (weakened virus).

LAIVs have been genetically manipulated to replicate efficiently at 25 degrees Celcius and not at all above 39 degrees Celsius. The genetic alteration limits the viral infection to cells in the cooler nasopharynx. LAIVs are manufactured to be delivered by intranasal mist. The immune system responds to the limited nasopharyngeal infection by producing antibodies.

FLU SHOT - IIV (Inactivated influenza vaccine)

  • All vaccines should be administered in settings in which personnel and equipment for rapid recognition and treatment of anaphylaxis are available.
  • Several different IIV preparations are available to meet specific needs within the population.

Who can benefit from the IIV Flu Shot (killed virus):

  • Flu shots are approved for use in people as young as 6 months of age and older.
  • Flu shots are approved for use in pregnant women and people with chronic health conditions.
  • Everyone 6 months of age and older should get a flu vaccine every season.
    • Children 6 months through 8 years of age may need two doses during the same flu season to reach immunity.
    • Reduced immune function in the elderly may require a vaccine with higher dose of antigen or an adjuvant to acheive adequate immune response. High dose vaccine may be 24% more effective in persons over 65 years.
  • Persons working in a healthcare settings should be vaccinated annually against influenza.

Who Should NOT Get a Flu Shot (killed virus)

  • Children younger than 6 months are too young to get a flu shot
  • People with severe, life-threatening allergies to flu vaccine or any ingredient in the vaccine. This might include gelatin, antibiotics, or other ingredients.
  • People who are moderately or severely ill with or without fever should usually wait until they recover before getting flu vaccine.
  • A history of Guillain-Barré Syndrome (GBS) within 6 weeks following receipt of influenza vaccine is a precaution for the use of influenza vaccine.

    Note: There are certain flu shots that have different age indications. For example, people younger than 65 years of age should not get the high-dose flu shot or the flu shot with adjuvant, and people who are younger than 18 years old or older than 64 years old should not get the intradermal flu shot.


Who should talk to their doctor before getting the flu shot:

  • History of allergy to eggs or any of the ingredients in the vaccine.
  • History of Guillain-Barré Syndrome (a severe paralyzing illness, also called GBS).
  • If you are not feeling well.


Immunizing Health Care Workers

Number of doses for children aged 6 months through 8 years: