10 Things to know about the seasonal flu vaccine - (WITH references)

Here are ten things to know about the seasonal trivalent influenza vaccine.

There is a new intradermal product in the mix. I actually got this along with my office mates. I LOVE it! No issues. Some of my office mate had some itching and swelling, just localized reactions. I had NO issues. I can see this would be a great alternative for those who had "needle phobia". It's just a little skin puncture. Easy.

(1) The H1N1 (derived from the pandemic 2009 influenza virus) and H3N2 A antigens and the B antigen are the same as last year. Essentially, it's the same vaccine we got last year.

(2) The Advisory Committee for Immunization Practices (ACIP) recommends vaccination for everyone six months of age and older, including pregnant women, without a specific contraindication.

(3) Protective serum antibody levels are reached in adults about 2 weeks post-vaccination and persist for at least 6-8 months.

(4) The vaccine should be offered as soon as it is available until the end of the flu season (May).

(5) FluMist is a cold-attenuated live virus vaccine approved only for healthy non-pregnant persons 2-49 years old.  FluMist seems to be more effective than the IM vaccine in children whereas the converse is generally true in adults.

(6) FluMist recipients may shed virus for a few days after vaccination, but person-to-person transmission has been rare and vaccine virus is unlikely to cause serious disease (which has never been reported) since it cannot replicate above 37 degrees C.  Nonetheless, FluMist recipients should avoid close contact with severely immunocompromised persons for 7 days after vaccination.

(7) Intradermal administration theoretically improves immunogenicity because of the high vascularity and large concentration of antigen-presenting cells in the dermis.  Fluzone Intradermal is 0.1 ml (not 0.5 ml) per dose, is injected through a shorter needle, and only has 9 mcg of influenza hemagglutinin antigen from each strain (the usual is 15 mcg).  Limited data indicate immune response comparable to the IM vaccine, but no published studies on the clinical efficacy of the vaccine against infection or illness are available. (we'll see how I do). The last time I had the REAL flu I felt like I was going to die....my skin hurt, my hair hurt. After that learning experience....I always get the shot.

(8) Fluzone High-Dose, an alternative to the standard IM vaccine for patients 65 and older, contains 60 mcg of hemagglutinin antigen from each strain (4x the usual).  It causes more injection-site reactions than the standard vaccine (as does Fluzone Intradermal, by the way).

(9) Influenza vaccination has very rarely been associated with Guillain-Barre syndrome, but so has influenza infection itself.

(10) Dosing of IM vaccine: 0.5 ml x1 if 3 years or older, 0.25 ml x1 if 6-35 months old.  Children <9 years old being vaccinated for the first time should receive two doses separated by at least 4 weeks (second dose given before December if possible).  Since this year's vaccine is the same as last year, children <9 who received only one dose of vaccine last year require only one dose this year (normally they would receive two).  Dosing of FluMist: 0.1 ml in each nostril x1; children 2-8 years being vaccinated for the first time should do this twice (separated by at least 4 weeks).

(11) BOTTOM LINE....GO GET YOUR FLU SHOT/INTERDERMAL INJECTION.  

REFERENCE

Influenza vaccine for 2011-2012.  Med Letter Drugs Ther 2011; 53: 81-83.