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Influenza virus Vaccine

Dictionary Meaning (Reader’s Digest Universal dictionary): A suspension of attenuated or killed disease-causing microorganisms, as of viruses or bacteria incapable of inducing severe infection but capable when inoculated, of stimulating the production of antibodies (and therefore conferring immunity) against the virulent microorganisms. Also defined in simple terms as a substance prepared from a weakened or killed microorganism, which when injected helps the body to build antibodies that will prevent infection by the natural micro organisms.

The flu vaccine protects a person against influenza caused by the virus. It is administered either by injection or inhalation.

Types of flu vaccines: Two types of fly vaccines have been identified and are presently in usage. The first type being Live but attenuated influenza vaccine (LAIV) was first approved and released for human use in 2003. It contains live but weakened influenza virus and is administered as a ‘nasal inhaler’. The second being inactivated or killed influenza virus vaccine that contains killed viruses and is given by intramuscularly as an injection. As the strain of influenza virus changes from year to year, a flu shot, unlike other types of vaccination is required to be administered recurrently every year. Each year the US Centers For Communicable Diseases Control predict the strains of influenza that may probably circulate in the next coming year. Vaccine manufacturers then produce vaccines that can protect against these typical types of flu. These vaccines are capable of only protecting a person against the type of influenza viruses from which they are made. They are usually of no considerable potential against other types influenza viruses.

Three types of influenza viruses: The three types of influenza viruses A, B & C differ by the proteins they carry on their outer surface. Type A viruses are found in animals and certain birds like duck, chicken, pigs, certain fish and horses. Type B virus circulates only and widely among humans. Type C virus though circulates only among human beings; causes mild infection and flu vaccine are not prescribed for such cases. Symptoms for influenza include fever, headache, fatigue, dry cough, sore throat, nasal congestion and body ache, for which paracetamol and other pain relievers can be used for symptomatic relief. Children complain of nausea and may have vomiting and diarrhea. But these symptoms may not appear in adults except the feeling of nausea.

Influenza virus vaccine may not guarantee complete safeguard against flu but will certainly reduce the risk of flu attacks and curtail the duration of the infection.

Reactions: Most people do not complain of any side effects or reactions of a flu vaccine except for tenderness and slight pain at the jab spot, that lasts a few days. The rare but greatest risk is an allergic reaction that can turn serious. A low intensity fever otherwise usually occurs.

Precautions: Flu vaccine should not be given to people who are on antibiotics for various other reasons or for the same flu. While both flu vaccines can be administered at the same time as other vaccines, if two vaccines are not given simultaneously at the same time, they should be spaced four weeks apart.

Both types of influenza vaccines may be administered to family members of immunosuppressed patients, as long as the patients do not require a protected environment although the killed virus vaccine is preferred for this purpose. Family members of patients who require a protected environment, such as people who have had organ transplants or are in intensive care units or are recovering from surgeries in post operative care rooms, should only be administered the killed virus vaccine through injection.

People in close contact with sick or affected persons should also receive the vaccine. Risk of localized reaction increases with age. Children below 13 years of age exhibit less reaction to the vaccine.