Post #32 Flu Vaccine Update 2012

How is the flu vaccine formulated?

Flu viruses are always changing. Each year, experts study thousands of flu virus samples from around the world to figure out which viruses are making people sick and how these viruses are changing. With this information, they forecast which three viruses are most likely to make the most people sick during the next flu season. These strains are then used to make the flu vaccine for the next flu season.

On February 23, 2012 the WHO recommended that the Northern Hemisphere’s 2012-2013 seasonal influenza vaccine be made from the following three vaccine viruses:

*an A/California/7/2009 (H1N1)pdm09-like virus

*an A/Victoria/361/2011 (H3N2)-like virus

*a B/Wisconsin/1/2010-like virus (from the B/Yamagata lineage of viruses)

While the H1N1 virus used to make the 2012-2013 flu vaccine is the same virus that was included in the 2011-2012 vaccine, the recommended influenza H3N2 and B vaccine viruses are different from those in the 2011-2012 influenza vaccine for the Northern Hemisphere.

When to get vaccinated?

Yearly flu vaccination should begin in September or as soon as the vaccine is available and continue throughout the influenza season, as late as March or beyond. The timing and duration of influenza seasons vary.

While influenza outbreaks can happen as early as October, most of the time influenza activity peaks in February or later. About 2 weeks after vaccination, antibodies that provide protection against influenza virus infection develop in the body.

How many shots will my child need?

This year’s seasonal flu vaccine will again include the Novel 2009 H1N1 vaccinewhich was used during the global pandemic and which was also included in the 2010-2011 and 2011-2012 seasonal flu vaccines. This means your child will only need to get vaccinated with ONE TYPE of flu immunization this year.

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If your child is 9 years or older, regardless of what flu immunizations have been given in the past, they will only need ONE immunization this flu season.

However, if your child is under 9 years of age, they may need TWO immunizations this year. See the chart below to assist you in knowing how many shots your child will need this flu season.

Please note that the decision tree sponsored by the CDC (Centers for Disease Control) and ACIP (Advisory Committee on Immunization Practices) are slightly different this year. Our office has decided to use the ACIP decision tree as it is more conservative.

If your child needs 2 flu vaccines this year, they should be spaced apart by a minimum of 4 weeks (28 days). There is no deadline by which the 2nd flu vaccine needs to be completed, but once the minimum 4 weeks has passed, the sooner the better as your child will have optimal protection only after the 2nd immunization.

0 flu shots since July 2010

1 flu shot since July 2010

2 flu shots since July 2010

Under 9 years of age

2 flu shots needed

2 flu shots needed

1 flu shot needed

9 years of age or older

1 flu shot needed

1 flu shot needed

1 flu shot needed

If your child is under 6 months of age, they are too young to receive the flu vaccine. It is imperative then for all surrounding family members (and caretakers) to receive the flu vaccine as soon as possible to create herd immunity. Essentially, if everyone surrounding the infant is protected, it decreases the risk that the baby will be exposed to the live flu virus.

Will a quadrivalent vaccine be available for the 2012-2013 season?

Traditionally, the flu vaccine covers 3 different strands of the flu virus and is labeled a trivalent vaccine. Starting next year some pharmaceutical companies will produce a flu vaccine that will be expanded to include 4 different strands of the flu virus thus adding 33% more protection.

Flu vaccine for the US market is produced and distributed by the private sector. While some manufacturers are planning to produce a quadrivalent (four component) vaccine in the future, quadrivalent vaccine is not expected to be available for the 2012-2013 season.

Of note, on February 29, 2012, quadrivalent flu vaccine manufactured by MedImmune, LLC was licensed by FDA for use in the United States.

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