The Influenza Vaccine – A Detailed Look at the Preventive Measure

Influenza is an infectious viral disease that can quickly turn complicated, and even fatal. The Advisory Committee on Immunization Practices (ACIP) recommends that the annual influenza vaccine be administered to all people above the age of 6 months. The vaccination should be scheduled before the arrival of the flu season so that there is sufficient time for the body to develop protective antibodies to fight against this dangerous condition. Annual vaccination is the mainstay of preventive measures against influenza.

influenza vaccine

The Live Attenuated Influenza Vaccine comes in the form of a nasal spray.

The Types Of Influenza Vaccine

The Food and Drug Administration (FDA) has licensed two influenza vaccines for use.

  1. The Flu shot (Trivalent Inactivated Influenza Vaccine / TIV)
  2. A Nasal Spray (Live Attenuated Influenza Vaccine / LAIV)

The influenza vaccine is an injectable vaccine that contains a strain of a dead flu virus and it can be administered to anybody older than 6 months. The second type of vaccine contains a live strain of the weakened flu virus (attenuated flu virus) in the form of a nasal spray. It is approved for individuals ranging from 2 years to 49 years of age, except pregnant women. Fluzone, an intradermal influenza vaccine is recommended for adults in the age group of 18 to 64 years.

Within two weeks of vaccination, the body develops antibodies to fight against the flu virus.

The Dosage, Administration, And The Storage Of The Influenza Vaccine

Except the intradermal vaccine, Fluzone, other TIVs should be injected intramuscularly, usually in the arms, and given in one or two doses. The first dose should be given as soon as the vaccine becomes available, to prime the immune system. The second dose, which is administered about four weeks or 28 days after the first dose provides the real protection. TIV is available under different trade names such as Flublok, Flulaval, Fluvirin, Fluarix, Agriflu, Afluria. LIAV is available under the trade name Flumist.

The TIV (injectable) and LIAV (nasal spray) vaccines should be stored at temperatures between 2°C and 8°C, and should not be frozen. LAIV also contains the same formulations as TIV, but is given intranasally. This vaccine is available in a prefilled single-use sprayer container with 0.2 ml of the vaccine. Approximately half of the container (0.1 ml) is administered into one nostril and the second half into the other nostril keeping the recipient in an upright position.

Influenza Vaccine Formulations

The 2012-2013 flu vaccine gives protection against the Influenza A H1N1 2009 pandemic virus, Influenza A H3N2 seasonal strain, and the Influenza type B virus. It is a trivalent (working against three viruses) vaccine formulation.

Influenza viruses undergo constant changes in their structure, as a result of which no vaccine can provide protection from this infection for long. Every year, the World Health Organization (WHO) revises and modifies the formulation of the influenza vaccine according to the influenza virus strain that is circulating in a given geographic area in the specified flu season.

Vaccines should be administered before the flu season, which may start as early as October and reach its peak activity in February. You can get the flu shot administered in clinics, health departments, or pharmacies.

The influenza vaccine is highly recommended for individuals who come under the high risk group, as they are prone to develop serious health conditions related to influenza.

Who Should Be Vaccinated

  • Young children in the age group of 6 months to 5 years of age
  • Adults older than 50 years of age
  • Individuals having health conditions like asthma, diabetes, lung or heart disease, neurologic or hematologic illnesses, or hypertension
  • Individuals with any immuno-compromised condition like pregnancy or HIV infection
  • Those who are taking immunosuppressive drugs
  • Health care workers like laboratory personnel, doctors, and nurses
  • Obese individuals with a Body Mass Index (BMI) of greater than 40
  • Patients undergoing aspirin therapy, who might develop complications due to a flu infection
  • Caretakers of patients having the influenza infection, and others who are in close contact with these patients

Who Should Not Be Vaccinated?

  • Children younger than 6 months old
  • People who are allergic to eggs
  • People who have a history of severe reactions to the influenza vaccine
  • Individuals who suffer from a condition called the Guillian Barré Syndrome, acquired from a  previous influenza vaccination
  • Individuals with a moderate or severe case of the flu, with or without fever
flu shot

Babies under six months of age should not be given the flu shot.

As the influenza vaccine can cause complications when administered to certain people, it is advisable to screen individuals before administering the vaccine, to ensure that the vaccine will not cause the person any harm.

Influenza Vaccine Side Effects

Even though seasonal flu vaccines have very good track records for safety, they can cause adverse effects in some cases. In many cases, mild side effects like nausea, headaches, redness and swelling at the injection site, fever, a runny nose, and muscle aches are observed.

In rare cases, serious adverse reactions like fainting, difficulty in breathing, paleness, and behavioral changes are also reported. If such reactions are observed, the patient should immediately be taken to the doctor. It is a myth that one can get the flu by vaccination, because the viruses in the vaccine are inactivated ones that cannot initiate infection inside the human body.

Getting influenza vaccine shots annually reduces the chances of infection to 60 %, protects you from severe flu-related complications including death, and also reduces the spread of the infection to others. It is considered the best defense against the flu infection.

This entry was posted in Influenza and tagged , by Dhanya V C. Bookmark the permalink.

About Dhanya V C

Dhanya (M.Sc) is a Senior Research Fellow at the Indian Veterinary Research Institute. A member of the FMD Virus Vaccine Production Unit, she specializes in Medical Microbiology, Biochemistry, Physiology, and Molecular Biology. She has over three years of professional experience.

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