Most people should aim to get a flu shot in early fall—ideally in September or October—so protection is strong when flu season ramps up in late fall and winter.

Quick Scoop

  • Flu season typically starts in October, peaks between December and February, and can last into May.
  • Your body needs about two weeks after the shot to build up good antibody protection, so getting vaccinated by the end of October is a sweet spot for most people.
  • Getting the shot in July or August can be “too early” for many adults because protection may wane before the end of flu season.
  • If you miss the September–October window, it is still worthwhile to get a flu shot later—even into January or beyond—as long as flu viruses are circulating and vaccine is available.

Who should get it, and when?

  • Health agencies recommend that almost everyone aged 6 months and older get a flu shot every year, with rare medical exceptions.
  • Older adults (65+) are often advised to prioritize a high‑dose or adjuvanted flu vaccine, usually given in late September or October to balance strong protection with waning immunity.
  • Many national programs plan adult vaccination to start around October and finish most doses by late November to align protection with the usual December–January peak.

Is it ever “too late”?

  • It is not considered “too late” as long as flu is still circulating in your area and the vaccine for that season has not expired.
  • Even if you get vaccinated after the peak months, it can still help, especially if there is a second wave or a prolonged season.

Information gathered from public forums or data available on the internet and portrayed here.