High Dose Influenza Vaccine

This 2010-2011 flu season offers the “high-dose” influenza vaccine to older patients.  It is indicated in patients > 65 years of age for seasonal influenza prophylaxis.  There are two schools of thought when it comes to the reasoning behind the high dose vaccine.  The first is that it is thought that a patient’s  immune system weaken as he/she grows older and are therefore not able to mount an immunologic response to an infection as well as a young patient.  The second thought is that aging also decreases the body’s ability to build a strong antibody response to the regular influenza vaccine compared with younger patients.  This goes back to the idea that if an older patient is exposed to a virus or bacteria, he/she is not able to mount an adequate response to fight the infection and they may not build a strong antibody response to protect them from future exposure.  As a result, the FDA approved a high-dose influenza vaccine this year for patients > 65 years of age. 
Fluzone High-Dose® vaccine has the same three components of the regular flu vaccine (H1N1, H3N2, and influenza B), but the dose has four times the amount of antigen.  The intent of the higher dose is to create a stronger antibody response in older patients. 
In terms of efficacy, the high-dose vaccine has resulted in higher serum antibody production in older patients.  Since this is a new vaccine, there are no data available stating that this increased antibody production has resulted in fewer cases of influenza.  Adverse reactions to the vaccine are rare; however, there are a greater number of adverse effects with the high-dose vaccine.  Adverse reactions include pain, redness and swelling at the injection site and headache, muscle aches, fever, and malaise.
We can still give older patients the regular seasonal influenza vaccine, but the concern is that their immune response to the vaccine may be suboptimal or not last them through the peak season of influenza (January, February).  If a patient requests the regular vaccine or if that is all that your clinic carries, it is recommended to wait until the end of October early November to give the regular vaccine to ensure that the patient maintains immunity throughout peak flu season.