How Does Flu Shots Work?

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Influenza is viral respiratory infection which affects a majority of population across the world. The infection is highly contagious and can spread on contact with the fluids which are dispersed while an infected person coughs or sneezes. Influenza and its related symptoms can be treated with anti viral drugs which would reduce the severity of the disease and prevent further complications. However, as the saying goes prevention is better than cure and there is no better way to prevent or reduce the risk of a person contracting this infection than an annual vaccination against flu.

Symptoms of Flu:

The symptoms and the duration of the flu vary from person to person. The common symptoms include fever, cough, sore throat, headaches, muscle aches and fatigue.

People Who Should Be Immunized Against Flu:

  • Infants below the age of two years
  • Children and Pregnant women
  • Elderly people above the age of 65
  • People with chronic lung, kidney, endocrine and blood diseases
  • Health care givers who would come into direct contact with flu infected people

How Does the Flu Vaccine Work?

Types of Flu Vaccines and the Way They Work:

Vaccines encourage the immune system to identify a virus and then produce antibodies to fight that infection. When your body actually encounters a virus then the corresponding antibodies are developed in the body to fight against that particular virus. The flu vaccine also acts on the same principle.

There are two types of flu vaccines available- the injectable flu shot and the nasal spray vaccine.

Injectable Flu Shots:

Trivalent and qaudrivalent variation of shots are available. The shot is generally administered in the arm and is composed of three strains of the predicted dominant flu strains for that particular year. The virus in the shot is deactivated or dead ones. When the shots are given the body’s immune system is activated to recognize the flu virus as harmful and produce the antibodies for it. When the person comes into contact with the flu virus again then the body produces the required antibodies to fight against the virus thus offering protection from flu.

Flu Vaccine as a Nasal Spray:

This is often referred to as LAIV (Live Attenuated Influenza Vaccine) where live but very weak strains of three types of flu virus are sprayed into the nose. The action of this vaccine is similar to that of the injectable form. This is usually recommended for healthy people aged between five and forty nine.

Benefits of Flu Vaccine:

  • It reduces the risk of a person contracting the flu virus by 70 to 90% and the severity of the severity of the symptoms if the virus is contracted.
  • Prevents the flu to develop into serious complications such as pneumonia
  • Vaccinations reduce the risk of flu related hospitalizations

When Should the Vaccine Be Given?

It is advised to get the flu vaccines earlier as the later you are into the flu season you face a higher risk of flu and it takes around a fortnight for the vaccine to offer complete protection.

Why Flu Vaccine is to be Taken annually?

The flu vaccines are modified every year according the prediction of the flu strains that might be dominant in that season. The predictions are approximate and are done by the WHO. Once a flu season is over you need to get vaccinated again the following year as the antibodies which are present in the body offers you protection only against the previous year’s flu virus. Also the body’s immunity reduces over time.


Though there is no guarantee that a person who has taken the flu virus would not get the flu it is better to get the annual flu shot for the benefits of the vaccination outweighs the actual treatment of flu.

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