Flu Vaccine Ingredients

The influenza virus (flu) is a common respiratory virus that impacts an estimated 1 billion people each year.  While the symptoms of the virus can be managed with medication, vaccination against the illness is one of the best proactive steps people can take to protect themselves from infection.  With some exceptions, the United States Centers for Disease Control and Prevention (CDC) and World Health Organization (WHO), recommend that everyone over six months of age get vaccinated against influenza every year.  People considering vaccination (commonly referred to as the “flu shot”), may be curious about what exactly is in a wake forest flu vaccine.

Main Ingredients in an Influenza Vaccine

Influenza Viruses:  It may seem counterproductive, but the vaccine contains small amounts of the viruses it protects against.  The influenza viruses contained in the shot are pandemic A (H1N1), influenza A (H3N2), and one or two influenza B (Victoria or Yamagata) strains.  Some vaccines contain three viruses (trivalent; both A strains and one B strain) or all four (quadrivalent).   Having the viruses in the vaccine, helps trigger a person’s immune system to produce antibodies to fight against the virus. The exact viruses included in the vaccine can differ slightly from year to year in order to provide the greatest chance of efficacy.

Formaldehyde:  Toxic and potentially lethal in higher doses, the amount of formaldehyde found in flu vaccines is so small that it is harmless.  Formaldehyde’s role in the vaccine is to make toxins from viruses and bacteria inactive so that they do not contaminate the vaccine during production.

Thimerosal:  A preservative that helps keep the vaccine free of bacterial and fungal contamination that could otherwise thrive in in a multi-dose vial.  The benefit of our practice is that Heritage uses syringes instead of Multidose vials so the vaccines we provide are FREE from preservatives. Made of an organic form of mercury (ethylmercury), thimerosal is safe and typically only remains in the blood for a few days. Since our Vaccines DO NOT carry this preservative there is no worry about being exposed to this substance.

Aluminum Salts:  Used in vaccines for more than 70 years, aluminum salts help boost the body’s immune response.  Because of this, the vaccine is able to contain small amounts of the virus.  Like most of the ingredients found in flu vaccines, such as formaldehyde, the amount of aluminum used in the vaccine, if used at all, is extremely small and not harmful.

Gelatin:  Gelatin (typically pork-based) is used in the flu vaccine as a stabilizer to ensure the vaccine remains effective from production to the time it is used.  Gelatin helps protect the vaccine from the damaging effects of freeze-drying or heat.

Chicken Egg Proteins:  Chicken egg proteins help viruses grow before they are used in a vaccine.  Flu viruses present in the vaccines are typically grown inside the fertilized eggs of chickens allowing the virus to make copies of itself.  Once copied, the viruses are separated from the egg and put into the vaccine.  While the finished vaccine may contain egg proteins, the amount present is small making it generally safe for people with egg allergies.  Despite the relative safety, people with egg allergies should inform their doctor prior to receiving the flu shot and could need monitoring following the injection.  Influenza shots that do not contain eggs are also available.

Antibiotics:  Also used to prevent bacterial grown during production and storage, antibiotics are present in flu vaccines.  Unlike penicillin, the antibiotics contained in flu vaccines, such as neomycin or gentamicin, do not cause severe allergic reactions.  Neomycin is an ingredient in many topical medications such as ointments, lotions, and eye drops. We have a screening form that is completed prior to any vaccine administration to ensure you are safe prior to administration.

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