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July 2010: Countries that banned H1N1 Flu vaccine

This year, Americans will be offered a Flu shot that has a combination of three different strains: Influenza B, H3N2 ("Hong Kong"), and the 2009 H1N1. But some countries are banning H1N1.

This month I will look at two countries that have banned H1N1 and see whether their reason for doing this is true here in the United States.


Finland has banned H1N1 because of an alarming rise in the number of narcolepsy cases (they had 15 cases following H1N1 flu injections).

Have narcolepsy rates associated with Flu shots changed in the United States?

To answer this question, we must define "narcolepsy" so that it can be found in MedAlerts searches. As usual, we will consult the MedDRA classification of symptoms. It shows narcolepsy in two different places:
Top-level termNext-level termMid-level term
Nervous system disorders   Sleep disturbancesNarcolepsy and hypersomnia
Psychiatric disordersSleep disorders and disturbances   Narcolepsy and associated conditions

So we will do this MedAlerts search:

Here is the graph:

The number of cases is shown below the date. We can see that in all of the years up to the 2006-2007 season, there were only rare instances of narcolepsy, sometimes 1 or 2, usually none. In the last 3 seasons the rate has increased, going to 12 in the 2007-2008 season, 14 in the 2008-2009 season, and a surprising 60 in the 2009-2010.

But this graph combines Seasonal Flu and H1N1, so how do we know whether H1N1 is responsible for the spike? If you separate the 60 events in the 2009-2010 season, 26 are from Seasonal Flu and 34 are from H1N1. So although Seasonal Flu was associated with a large number of narcolepsy cases, H1N1 was found in even more of these events.

It appears that Finland's experience with the Flu vaccine is also happening here in the United States.


Australia has banned H1N1 because of 23 convulsion cases (mostly in children).

The MedDRA places convulsions here:

Nervous system disorders    Seizures (incl subtypes)    (top-level term)    (next-level term)

So we will do this search:

Here is the graph:
The spike this year is easy to see: the 2009-2010 flu season had 587 events that indicate seizure-related symptoms and the administration of a Flu vaccine (274 for H1N1 and 313 for Seasonal Flu). Last year had only 132 events and the year before, 139.

Let's look in detail at the 2009-2010 season to see if children are more strongly affected (as Australia claims). Here is a graph of H1N1 flu associated with convulsions, broken down into three age groups: under 5 years old, 5 to 10 years old, and over 10 years old (these are the cut points for policy recommendations):

The children under 5 years of age are indeed more affected by the H1N1 vaccination.

So as with Finland, it seems that Australia's experience with the flu vaccine is also happening here in the United States.

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