Though the 2011 flu season is still three months away, flu vaccines are already on the way. Looking to avoid a potentially crippling shortage of vaccines, some drug manufacturers are disbursing shipments early. This year’s formulation is similar to last year’s, offering protection against a range of type A and B strains. This includes the H1N1 virus, otherwise known as swine flu. Even if you had a flu shot last year, you’ll need it again this time around. The immunity offered only lasts for a short period. The CDC recommends influenza vaccination for anyone six months and older. Different forms of flu vaccine are approved for different age groups. Six drug manufacturers are licensed to produce and distribute flu vaccines in the United States this year, according to the FDA. One of these manufacturers, Novartis, has already begun to ship its Fluvirin vaccine.