The vaccine recommended for the coming flu season will protect against the same three viruses that last year's flu vaccine did, a report from the Centers for Disease Control and Prevention (CDC) said today.

Still, those who received the influenza vaccine last season should get vaccinated again, because the vaccine's protective effect declines over time, said the agency's Advisory Committee on Immunization Practices.

The vaccine includes three strains of the virus, one of which is derived from the 2009 H1N1 virus, the committee said.

The committee recommended the vaccine for all people over 6 months old, and said that people should get vaccinated before flu season begins, so the immune system has time to produce the antibodies needed to ward off flu infections.

Children ages 6 months to 8 years who didn't get vaccinated last year need two doses of the vaccine, given at least four weeks apart, the committee said, citing a 2006 study from University of Washington researchers that showed significantly greater protection after two doses than after one. Two doses should also be given if medical providers are not sure whether a child was vaccinated last year.

However, because the vaccine is unchanged from last year's, kids who received at least one dose last year need one dose this year, the committee said.

People who have previously had severe allergic reactions to an influenza vaccine should not be vaccinated, the committee said.

Some people with egg allergies may be safely vaccinated — they should receive the inactivated form of the vaccine, which is injected into the muscle, rather than the live (but weakened) virus vaccine, which is given via an intranasal spray, the committee said.

However, anyone with an egg allergy should consult with a health care professional familiar with potential allergic reactions. Those with more severe reactions who are deemed safe for vaccination should receive the vaccine only in a setting where rapid treatment of a severe anaphylactic reaction is possible, the committee said.

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