It takes about two weeks for your immune system to create enough antibodies to help protect you from the flu. If you're considering getting a flu shot later in the flu season but are worried that it's too late to get a flu shot—if there's any flu activity occurring, then it's not too late at all.

It takes up to two weeks to build immunity after a flu shot. 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 the flu vaccine in September and October. Aim to get it by the end of October.

Medicare covers the flu shot Medicare Part B (Medical Insurance) covers one flu shot per flu season. You pay nothing for a flu shot if your doctor or other health care provider accepts assignment for giving the shot.

Flu vaccination is safe during pregnancy. Pregnant women should get a flu shot; NOT the live attenuated vaccine (LAIV or nasal spray). Postpartum women, even if they are breastfeeding, can receive either type of vaccine. There is a lot of evidence to show that flu shots can be safely given to women during pregnancy.