Monday, May 17, 2010

Adverse events following influenza vaccination in Australia--should we be surprised? BMJ Rapid Response

From the May 7 BMJ Online, authored by Peter Collignon, Peter Doshi, Tom Jefferson
There have been large numbers of major adverse reactions to this year's seasonal influenza vaccine in Australia, and the vaccine has been suspended for use in children aged five and under... Assuming all convulsions were in children, about one child in every 500 vaccinated had a febrile convulsion.  Across Australia, media accounts indicate that more than 400 adverse reactions [3] including 77 cases of febrile convulsion [1] have been reported by regulators.  While attention remains focused on reactions in very young children, reports suggest only one-third of the reactions may have occurred in children under five [4].

Although this situation has triggered considerable controversy in Australia, the story has attracted little to no media attention in the US and Europe.  Similarly, the media has paid little attention to a US H1N1 federal vaccine safety advisory committee which recently reported detecting signals for Guillain-Barre syndrome (GBS), Bell's palsy, and thrombocytopenia in the monovalent H1N1 (swine flu) vaccine [5]. The same monovalent H1N1 antigen component under review in the US is scheduled to be added to the US trivalent seasonal vaccine and is contained in the Australian trivalent seasonal vaccine and will be given to children, pregnant women and adults...

Overall, the percentages of children under three who developed a fever after vaccination appear very high; thirty five per cent with the 15 ug dose and 62% after a 30 ug dose [7,8]. Of those that received a 7.5 ug dose in the seasonal influenza vaccine, 23% develop a fever of >38 degrees Celsius [6]... If such a large proportion of children develop high fevers, it is also likely that a substantial number will develop febrile convulsions as a result of vaccination. It is thus surprising the vaccine was approved for this age group...

There are actually relatively little data on the effects of vaccinating young children against influenza [10]. Some manufacturers have even withheld data from public scrutiny amidst general indifference [10,11].  Evidence from all comparative influenza vaccine studies shows that harms, when they are investigated, are not reported consistently and systematically [10,11]. As pandemic vaccines are provided to governments and not individuals and manufacturers are indemnified for damages caused to users [12-14], there seem to be few incentives for investigation of harms...

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