Saturday, July 31, 2010

This year's seasonal flu vaccines

Flu vaccine is being recommended for the entire US population over 6 months of age, starting this year.

The (non-live) vaccines will contain 3 antigens, one of which is the antigen used for swine flu vaccines since late 2009.

In 2009, DHHS Secretary Sibelius issued a Public Readiness and Emergency Preparedness Act waiver of liability for injuries from swine flu vaccines, which expired June 23. Here is the law describing duration of such waivers.  Thus one should be able to sue manufacturers for injuries sustained as a result of this season's flu vaccine.

However, a similar vaccine used in Australia caused one in 110 children to have a seizure recently, so its use was prohibited in children under five while a panel is investigating the possible cause.  Although US public health agencies are well aware of this problem, US authorities chose to recommend the same flu vaccine for all children aged over 6 months.

UPDATE: In the UK, according to the Telegraph, the Department of Health has written to all GPs to avoid giving flu vaccines from manufacturers CSL and Pfizer to children under five:
The letter to all GPs from Prof David Salisbury, said: "Epidemiological information from Australia indicates that there has been a higher than expected increase in febrile convulsions in children related to the use of Fluvax (manufactured by CSL).
"This is the same product that will be marketed in the UK by Pfizer as Enzira and generic influenza vaccine for the 2010/11 influenza vaccination season.
"Evidence from Australia suggests a rate of febrile convulsions of about one per 100 for children who were vaccinated with Fluvax. This increased risk appears to be a product specific reaction and evidence from Australia of vaccination with other products has so far not indicated a similar level of risk.
"It is important that children over six months of age who are in clinical risk groups receive influenza vaccination. Given the availability of other influenza vaccine products, you should avoid offering Enzira or CSL Biotherapies generic influenza vaccine marketed by Pfizer to children aged under five years."
Furthermore, CDC plans to roll out the shots earlier than usual this flu season, during August.  That makes little sense.

Seasonal flu epidemics almost never start before December.  It takes up to 2 weeks to get maximal immunity from one vaccine dose.  Immunity wanes rapidly.  Therefore, there is no reason to get vaccinated before late November.

Furthermore, there has been almost no swine flu in the southern hemisphere this 2010 flu season (their winter is our summer).  Only 5 cases have been recorded so far this season in Tasmania, which has a population of 500,000, of whom less than 1/3 have been vaccinated.  I wonder if a much higher proportion of the Australian and US population was exposed and became immune last year than the 20% reported.  Exposure gives you much stronger and longer-lasting immunity than vaccination.

So it is likely the swine flu component of the vaccine will be unnecessary.  Australians suspect that is what is contributing to adverse reactions.  Canadians might suggest the combination is unsound.  No one knows for sure.  There is plenty of time to observe the trends of viral activity, and the adverse effect profile of the vaccine, before those in the northern hemisphere need to make a decision about whether the vaccine is likely to provide them net benefit or harm.

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