The Advisory Committee on Immunization Practices (ACIP) of the Centers for Disease Control and Prevention has issued updated guidelines for the use of influenza vaccine and antiviral agents for prophylaxis and treatment of influenza A. The full report was published in the July 28, 2006, issue of Morbidity and Mortality Weekly Report and is available athttp://www.cdc.gov/mmwr/preview/mmwrhtml/rr55e628a1.htm.

Changes from previous recommendations include the following:

• Neither amantadine (Symmetrel) nor rimantadine (Flumadine) should be used for chemoprophylaxis against influenza A because of recent data indicating widespread resistance of influenza viruses to these medications. Until susceptibility to these agents has been reestablished among circulating influenza A viruses, oseltamivir (Tamiflu) or zanamivir (Relenza) may be prescribed if antiviral treatment or chemoprophylaxis of influenza is indicated (Table 1).

• Children 24 to 59 months of age and their household contacts and out-of-home caregivers should be vaccinated against influenza. This change extends the recommendations for vaccination of children so that all children six to 59 months of age are vaccinated annually (Table 2).

• Previously unvaccinated children six months to less than nine years of age should receive two doses of influenza vaccine. Children six months to less than nine years of age who receive trivalent inactivated influenza vaccine should have a booster dose administered at least one month after the initial dose, before the onset of influenza season, if possible. Children five to less than nine years of age who receive live, attenuated influenza vaccine should have a second dose six to 10 weeks after the initial dose, before the influenza season, if possible. If a child six months to less than nine years of age was vaccinated for the first time during a previous influenza season but did not receive a second dose of vaccine in the same season, only one dose of vaccine should be administered this season.

• Health care professionals should routinely offer influenza vaccine to patients throughout the influenza season, even after influenza activity has been documented in their communities.

• The 2006-2007 trivalent influenza vaccine virus strains include A/New Caledonia/20/1999 (H1N1)-like, A/Wisconsin/67/2005 (H3N2)-like, and B/Malaysia/2506/2004-like antigens. For the A/Wisconsin/67/2005 (H3N2)-like antigen, manufacturers may use the antigenically equivalent A/Hiroshima/52/2005 virus; for the B/Malaysia/2506/2004-like antigen, manufacturers may use the antigenically equivalent B/Ohio/1/2005 virus (Table 3).