All children and adolescents at least six months old should receive annual flu immunization. However, groups most susceptible to influenza-related complications should be specially targeted for vaccination: all family members, household contacts, and out-of-home care providers of children younger than five years; children with asthma, diabetes, neurologic diseases, or other high-risk conditions; healthcare personnel; and pregnant women.
The 2011-2012 U.S. seasonal influenza vaccine virus strains are identical to those contained in the 2010-2011 vaccine. These include A/California/7/2009 (H1N1)-like, A/Perth/16/2009 (H3N2)-like, and B/Brisbane/60/2008-like antigens. The influenza A (H1N1) vaccine virus strain is derived from a 2009 pandemic influenza A (H1N1) virus.
The child's age when receiving the first influenza vaccine dose and vaccination history determines the number of influenza vaccine doses each child needs, as summarized in a flow chart provided in the policy statement.
Specific guidelines concerning the required number of influenza vaccine doses are as follows:
Children younger than 6 months are too young to receive influenza vaccine.
Children aged 6 months through 8 years who received only 1 dose of influenza vaccine in their first year of vaccination required 2 doses the following season. However, because the 2011-12 vaccine strains are unchanged from the 2010-11 season, children in this age group who received at least 1 dose of the 2010-11 seasonal vaccine will require only 1 dose of the 2011-12 vaccine. Children in this age group who did not receive at least 1 dose of the 2010-11 seasonal influenza vaccine, or for whom it is not certain whether the 2010-11 seasonal vaccine was received, should receive 2 doses of the 2011-12 seasonal influenza vaccine.
Children younger than 9 years require at least 2 doses of 2009 pandemic H1N1 vaccine. They will need 2 doses of seasonal influenza vaccine this year if they did not receive the H1N1 vaccine during last year's influenza season.
Children younger than 9 years who have never before received the seasonal influenza vaccine will require 2 doses.
Children younger than 9 years who received seasonal influenza vaccine before the 2009-2010 influenza season, need only 1 dose this year if they received at least 1 dose of the H1N1 vaccine last year, but they need 2 doses this year if they did not receive at least 1 dose of the H1N1 vaccine last year.
Children younger than 9 years who received seasonal influenza vaccine for the first time last year, but who only received 1 dose, require 2 doses this year.
For children younger than 9 years who received influenza vaccine last year, but for whom it cannot be determined whether it was a seasonal influenza vaccine or the H1N1 influenza vaccine, 2 doses are recommended this year.
For all children who require 2 doses, the second dose should be administered at least 4 weeks after the first dose.
FIGURE 1. Influenza vaccine dosing algorithm for children aged 6 months through 8 years --- Advisory Committee on Immunization Practices (ACIP), 2011--12 influenza season