H1N1 vaccine update

In the month since my last flu vaccine post, I've received tons of questions.  Time for an update.

When I last wrote, it was not clear to me a) what the flu season would look like and b) what the actual H1N1 vaccine would be.  While I still am not clear that IN GENERAL, this flu season is going to be any worse or better than typical flu seasons, it does seem that some populations (pregnant women, school age children) are being hit harder than one might expect.  To add to the confusion, there are huge regional differences in infection rates and severity of flu.  For example, as reported by the New York Times, the Northeast (where I practice) seems to be fairly mild right now – is that because we saw a lot of H1N1 this spring/summer?  Or just not our time yet?  The cases I have seen are typically mild.  Almost no one needing the ER or (knock on wood many times) hospitalization.  It would be nice if that trend continued.

So – what about the actual H1N1 vaccine constitution?  Turns out that the formulations available at the current time are made by the same manufacturers as the regular seasonal flu vaccines and in the same exact manner.  Meaning this – most of the supply in multi-dose vials contains 25 mcg thimerosal per dose.  There are single dose thimerosal-free injectable version available – though I haven't heard of any or seen any in the NY/NJ area to date.  We did receive a small shipment of nasal live attenuated "FluMist" H1N1 last week.  The good news is that, as with the seasonal FluMist version, it is thimerosal-free and relatively easy to administer.  In children, this version seems to be more effective than injectable.  It is only licensed for use in ages 2-49 and in those people without significant asthma or immune deficiency states (which rules out its use in most of our highest-risk populations).  

So…. what's the bottom line?  Am I recommending H1N1 vaccine for all kids?  I am obligated to inform you and all of my patients that both the CDC and AAP have recommended it for all kids 6 months and older.  To be honest, I don't have access to appropriate supply to carry this out even if I wanted to.  Also, H1N1 vaccination requires 2 doses to be given to children under 10.  And if you've never had the seasonal flu vaccine, and you're under 9, you need 2 doses of that as well.  We have absolutely no data regarding safety and efficacy of this approach – up to 4 doses of flu vaccine in a short time period; up to 100mcg thimerosal in total.  THAT possibility does concern me greatly.  So it's really hard to make blanket recommendations given that informed consent requires an adequate assessment of risk/benefit.  On the one hand, if you typically give your children the seasonal flu vaccine, it is a bit inconsistent to avoid the H1N1 vaccine.  It is only "new" in the same exact sense that each year, the seasonal flu vaccine is "new" – the included antigen strains are changed each year to mimic what we believe will be the active circulating strains.  On the other hand, if you avoid flu vaccine always, you are not likely to line up for the H1N1 version.  On balance, I think that, if you can get a thimerosal-free version, it is worth considering especially if you are considered higher-risk.  Once again, I think these decisions are best made on a case-by-case basis with your physician.  Please take your time and consider the pros and cons for YOUR child(ren).

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