The recipe for the 2006–2007 influenza vaccine calls for A (H3N2) and B strains that differ from last year's version, according to analyses of recently isolated flu viruses, epidemiologic data, and postvaccination serologic studies in humans.
Vaccine manufacturers should include the A/New Caledonia/20/99-like (H1N1), A/Wisconsin/67/2005-like (H3N2), and B/Malaysia/2506/2004-like viruses in formulations of the 2006–2007 influenza vaccine, recommends the Food and Drug Administration's Vaccines and Related Biological Products Advisory Committee (MMWR 2006;55:648–53). Last year's vaccine included the emerging strain A/California/7/2004 (H3N2) and retained the H1N1 and B strains from the previous year.
During last year's flu season (from Oct. 2, 2005 to June 3, 2006), 35 deaths were reported among children aged less than 18 years, which were linked to laboratory-confirmed influenza infections from 13 states. Of the 31 children for whom the type of virus was known, 23 were infected with the influenza A virus, and 8 were infected with the influenza B virus. A total of 11 deaths occurred in children aged 6–23 months, 4 in children younger than 6 months of age, 4 in children aged 2–4 years, and 16 in children aged 5–17 years, the Centers for Disease Control and Prevention said.
Pediatric hospitalizations with lab-confirmed influenza infections were monitored in two networks. The pediatric hospitalization rates from last year's flu season showed an overall rate of 1.21/10,000 children aged 0–17 years, based on preliminary data from the Emerging Infections Program. When broken down into younger and older age groups, the rates were 2.76/10,000 among children aged 0–5 years and 0.38/10,000 among those aged 5–17 years. Furthermore, the laboratory-confirmed influenza-associated hospitalization rate was 5.4/10,000 children for children aged 0–4 years, based on preliminary data from the New Vaccine Surveillance Network.
In the 2005–2006 season, influenza A (H1N1), A (H3N2) and B viruses cocirculated all over the world, the CDC said.