Do they give flu vaccines in the summer or winter?

Each year: the new flu shots come out in early fall. When the vaccine is actually available depends on the private manufacturers. Try to get it as early as possible - ie. August - September as flu cases may start increasing around October. Even it you get it later in the season - still try to get it.

Flu shot: Flu shots are given in the fall and early winter. Better sai between the end of September and the end of March