When is the flu vaccine available?

Private manufacturers make the flu vaccine and take about six months to produce it. The availability of the flu vaccine depends on when production is completed. But generally, shipments begin sometime in August in the United States. Doctors and nurses may begin vaccinating people as soon as the flu vaccine is available in their areas.

It takes up to two weeks to build immunity after a flu shot, but you can benefit from the vaccine even if you don't get it until after the flu season starts. It's usually best for people in the United States to get their flu vaccine in September and October, and aim to get it by the end of October. However, you can still protect yourself against late flu outbreaks if you get the vaccine in February or later.