In one of my recent posts, I discussed some important facts about the upcoming 2012-2013 influenza season. Today, I’d like to review some of the formulations of influenza vaccine available that is imperative for clinicians to know.
The economic impact of seasonal influenza on the United States economy is staggering. According to Molinariet al., direct medical costs of influenza account for an estimated $10.4 billion dollars, $16.3 billion dollars in loss of projected earnings and a total of $87.1 billion in projected statistical life values. The Centers for Disease Control (CDC) estimates approximately 200,000 people are annually hospitalized from influenza-related complications and about 36,000 people die from influenza-related causes. Therefore, it is essential to try and prevent this very costly and deadly seasonal virus via vaccination.
This flu season, we will widely see new formulations of the vaccine along with the traditional variety. All forms of influenza vaccine are still egg protein-based so severe allergic reactions to eggs are a contraindication to vaccination. **The information below is for informational purposes only. Every effort was used to ensure accuracy though all providers should verify package information prior to administration.**
All varieties of the 2012-13 trivalent (containing three strains) vaccine has the following strains:
- an A/California/7/2009 (H1N1)pdm09-like virus;
- an A/Victoria/361/2011 (H3N2)-like virus;
- a B/Wisconsin/1/2010-like virus (from the B/Yamagata lineage of viruses).
Inactivated Influenza Vaccine
- Intradermal Flu Vaccine: First introduced in the 2011-12 flu vaccine season. Available as Fluzone Intradermal, this vaccine is indicated for those 18-64 years of age and uses a needle that is 90% smaller than the traditional needle. The dose is 0.1 mL. One downside is that there are more localized reactions with this method (i.e. redness and swelling at the injection site). I was recently shown how to use this device and it comes fully assembled and ready to use (no need to add a needle) with a built-in safety feature. It takes some practice using it as it differs from a traditional intramuscular injection. Another downside that it costs more than traditional flu vaccine so some insurers may cover it while others may not. This vaccine is latex and preservative free though costs more than traditional vaccine. Here is a short video on the micro-needle delivery system.
- High-Dose Fluzone: Is indicated for patients 65 years and older. This is a traditional intramuscular vaccine and is both latex and preservative free that has been FDA approved in 2009. The dose is 0.5 mL. This formulation is made with 4 times the antigen content of traditional vaccine and has shown an increased immune response for those individuals receiving it. Therefore, for those older adults with immunocompromised immune systems, this vaccine has shown to provide greater immunity than the standard dose.
- Pediatric Flu Vaccine: Indicated for children 6 months – 35 months of age. This is also preservative free and the dose is 0.25 mL administered intramuscularly. *Providers should follow the graphic below to determine if children (aged 6 months to 8 years of age) should receive 1 or 2 doses of vaccine (separated by at least 4 weeks apart).
- Standard Flu Vaccine: Indicated for those 36 months of age and up. The dose is 0.5 mL and administered intramuscularly. The pre-filled syringes are preservative free whereas the multi-dose vial does contain preservative.
The figure above shows influenza vaccine dosing algorithm for aged children 6 months through 8 years in the United States, during the 2012-13 influenza season. Children are recommended to receive 2 doses this season, even if 2 doses of seasonal influenza vaccine were received before the 2010-11 season. This is illustrated in two approaches for determining the number of doses required for children aged 6 months through 8 years, both of which are acceptable.
Live Influenza Vaccine
FluMist: is an attenuated live flu virus vaccine that was first approved by the FDA in 2003. FluMist is indicated for patients from 2 years of age to 49 years of age only. This live flu vaccine is administered intranasally (the dose is divided evenly into both nostrils) and is preservative free. Here is a demo of intranasal administration.
FluMist should not be administered to patients with a history of asthma and/or patients who are immunocompromised or those living with immunocomprised household contacts since the virus is live.
One particular note about FluMist is that in a large study of children by Belshe et. al, (2007), FluMist as live vaccine was more effective than traditional inactive vaccine for preventing influenza. One theory that has been postulated is that since the nasal anatomy is smaller in children, the vaccine was better absorbed and thus had a better immune response.
The 2012-13 flu vaccine will have NINE different flu products:
It is vital for providers to become familiar with these options since there are so many and it can be quite confusing. It is actually a great thing for patients needing/wanting the vaccine since there is redundancy with vaccine manufacturers to help ensure adequate supply (versus 2004 when the manufacturer Chiron, who was supposed to supply half of US supply of flu vaccine had contaminated vaccine causing a severe shortage). Keeping track of all of them is the real challenge!