According to the Centers for Disease Control and Prevention, although October and November are the recommended months for vaccination, a flu vaccine given later in the season -- December through March -- still can help protect from influenza.
This year, flu vaccine manufacturers plan to have more then 130 million doses of influenza vaccine available for distribution in the United States, more than ever before.
The two vaccines available to the public are:
The traditional injectable flu vaccine, which contains inactivated (killed) virus, is for anyone age 6 months and older. Some patients experience soreness at the injection site lasting less than two days, but serious side effects are extremely rare. This vaccine may come in a multiple-dose vial or in single-dose syringes. Syringes for children 3 and younger are thimerosal-free.
A live weakened virus vaccine called LAIV or "FluMist" is sprayed into the nose and is for healthy people ages 2 through 49. A small amount of vaccine is sprayed into each nostril, instead of getting an injection.
Source: CDC, Public Health -- Seattle & King County