CDC: All Americans should get a flu shot

For the second year in a row, U.S. health experts are urging all Americans to get a flu shot, even though the circulating strains of flu have not changed since the 2010-2011 flu season.

The U.S. Centers for Disease Control and Prevention said the recommendations apply to everyone older than 6 months of age, even those who got shots last year against the same flu strains.

This year's vaccine protects against H1N1 swine flu and two other strains called H3N2 and influenza B. The CDC said it was possible that immunity provided from last year's shots, which included the H1N1 pandemic flu strain, may have faded.

The new recommendations from the CDC's Advisory Committee on Immunization Practices, published in the agency's weekly report on death and disease, also cover Sanofi-Aventis' newly approved Fluzone Intradermal vaccine for adults aged 18 to 64.

The vaccine, which uses a short needle and delivers the vaccine into the skin rather than the muscle, can be used as an alternative to traditional vaccines.

The five companies that make flu vaccine for the U.S. market expect to provide 166 million doses of it this season, CDC said. Last year, 157 million doses were distributed.

Children aged 6 months to age 8 getting a flu shot for the first time will need two shots, at least a month apart, to build up immunity, the CDC says. Those in that age group vaccinated last year will need only one shot.