What is an Influenza Vaccine?

Influenza (flu) is a common respiratory virus that infects the throat, nose, and lungs.  The virus primarily spreads through person to person contact when droplets from infected people are sent into the air after sneezing, coughing, or talking.  Symptoms typically develop quickly after exposure and may include fever, chills, cough, congestion, sore throat, fatigue, and nausea.  It is estimated that around 1 billion people contract the virus each year so chances are you, or someone you know, have been infected with the flu at some point.  While prescription and over the counter medicines are available to combat the illness, one of the best preventative measures people can take to safeguard themselves from the virus is to get vaccinated.

What is the Influenza Vaccine?

Commonly referred to as the “flu shot”, influenza vaccines protect patients against infection from the flu virus.  Most frequently administered as an injection in a person’s upper arm, the vaccine is sometimes available in a nasal spray form.  The United States Centers for Disease Control and Prevention (CDC) and World Health Organization (WHO) recommends yearly vaccination for virtually all people six months of age and older.  The vaccine is particularly recommended for high risk people such as pregnant women, those with certain health problems, the elderly, young children (six months to five years of age), and healthcare workers.

There are two main types of influenza vaccine:

  • Inactivated Influenza Vaccines (IIV): The viruses included in IIV are not active so while they will not cause the flu, they can sometimes result in minor side effects such as soreness or reaction at the injection site, transient fever, muscle pain, or tiredness.  IIV is approved for use in patients six months of age or older, pregnant women, and people with chronic medical conditions.  However, children (six months to eight years of age) that did not receive a seasonal flu vaccine during the previous influenza season, it is recommended they be administered two doses at least four weeks apart.
  • Live Attenuated Influenza Vaccines (LAIV): Viruses included in LAIV are weakened but also do not cause influenza.  While the side effects of LAIV are similar to those of IIV, symptoms are mild and much less severe than a full-blown case of the flu.  LAIV has restrictions similar to IIV for children ages two to eight years old that did not receive a vaccine during the previous flu season.  These patients should also receive two doses administered four weeks apart.

Which Strains of Influenza do the Vaccines Guard Against?

There are four strains of seasonal flu virus that the vaccine can combat:  pandemic A (H1N1), influenza A (H3N2), influenza B (Victoria), and influenza B (Yamagata).  Some vaccines protect against three of the strains (trivalent) while others can protect against all four (quadrivalent).  The specific strain of influenza that goes around each year varies and the vaccines are updated accordingly.  The WHO’s Global Influenza Surveillance and Response System (GISRS), monitors virus samples collected from around the world on an ongoing basis to advise on which strain is most likely to be applicable during an upcoming influenza season.  From this data, the composition of influenza vaccines is updated annually before production.  Production of the vaccine takes roughly six months so having the most current, and accurate, data available before manufacturing is critical in determining the vaccine’s effectiveness. Heritage is always up to date and current with the guidelines, thus providing only the most up to date vaccine and the most potent strain available.

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