What you should know about influenza or flu vaccines

November 4, 2013 Susanna Block, MD

Influenza or the “flu” is a contagious viral disease that occurs every winter in the US from October to May.  While anyone can get a “flu” infection, some people are especially vulnerable and at risk for severe disease.  Each year thousands of people die from influenza infections and many more are hospitalized.  Getting your annual flu vaccine is the best protection against the flu and its complications.

The influenza virus is spread by coughing, sneezing and close contact.  The symptoms can occur quite suddenly. Typical symptoms are high fevers and chills, sore throat, muscle aches, fatigue, cough, headache and runny nose.  Although anyone can get the flu, children, people over 65 years old, pregnant women and people with chronic health conditions are at risk for severe disease and complication. 

The flu virus is always changing. Each year the flu vaccine is made to protect from the virus strains most likely to cause disease.  Typically the vaccine protects against 3-4 different influenza types. It takes 2 weeks to develop protection after the influenza vaccine is given.

Which flu vaccine is best for me?

Two types of influenza vaccine are currently available. It is always best to talk with your physician about which vaccine is best for you and your children.  The two different available vaccines are:

  • The “flu shot” or inactivated vaccine

    The inactivated vaccine or “flu shot” does not contain any live influenza virus and is given by injection with a needle.  Children over the age of 6 months are eligible to receive the flu shot. The first time a child receives a flu shot they need 2 doses given 1 month apart. After that it is an annual vaccine at the beginning of flu season.
  • The “nasal spray” or live attenuated vaccine

    The live attenuated “nasal spray vaccine” does contain live viruses (unlike the flu shot), but the viruses are attenuated (weakened) and cannot cause flu illness.  This vaccine is approved for use in healthy people 2 through 49 years of age who are not pregnant. The following people should not receive the live attenuated vaccine:
  • Children younger than 2 years
  • Adults 50 years and older
  • People with a history of severe allergic reaction to any component of the vaccine or to a previous dose of any influenza vaccine
  • People with asthma
  • Children or adolescents on long-term aspirin treatment.
  • Children and adults who have chronic pulmonary, cardiovascular (except isolated hypertension), renal, hepatic, neurologic/neuromuscular, hematologic, or metabolic disorders
  • Children and adults who have immunosuppression (including immunosuppression caused by medications or by HIV)
  • Pregnant women
  • Moderate or severe acute illness with or without fever is a general precaution for vaccination. GBS within 6 weeks following a previous dose of influenza vaccine is considered a precaution for use of influenza vaccines
  • People who have received the nasal spray flu vaccine may shed low amount of vaccine viruses after vaccination. While there are no cases of serious illnesses associated with this, the nasal spray vaccine is not recommended for those who are caring for others with severely weakened immune systems.

What are the risks of the flu vaccine?

Like any medication there is a chance of side effects with the flu shot.   The most common side effects are feeling sore or noting redness at the site of the injection, cough, aches, fever, itching, and fatigue. Typically these symptoms last 1-2 days and resolve completely.   More severe side effects can be seen in young children who get the inactivated flu vaccine at the same time as pneumococcal vaccine (PCV 13). These patients are at increased risk for seizure caused by fever. Very occasionally (less than 1 in a million people) have a severe allergic reaction to the vaccine.  Also very occasionally (1-2 people in 1 million) will develop Guillan Barre Syndrome from the vaccine. The rate of GBS from the vaccine is less than the rate of GBS from an influenza infection. Some people should not get the “flu shot”.  People with severe (life threatening) allergies to eggs or who have had Guillan-Barre Syndrome are not good candidates for the influenza vaccine. 

In children, side effects of the nasal spray vaccine can include runny nose, headache, wheezing, vomiting, muscle aches, and fever. In adults, side effects of the nasal spray vaccine can include runny nose, headache, sore throat, and cough. Fever is not a common side effect in adults receiving the nasal spray flu vaccine.

For more information about influenza and the influenza vaccine, visit www.cdc.gov/flu

Previous Article
Fall in love with pumpkin
Fall in love with pumpkin

The season’s clock has turned to autumn. The air is crisp, vibrant shades of red and orange color the tre...

Next Article
Is the FODMAP diet right for you?

FODMAPs is an acronym, coined by two Australian researchers, that refers to Fermentable Oligosaccharides,...