Early seasonal influenza vaccination and delayed influenza peaks - A possible cause of end-of-season outbreaks

- Intra-seasonal waning of influenza vaccine-induced immunity is now well-recognised.
- Late seasonal influenza incidence is regular and predictable in some populations.
- Despite a good vaccine match this may lead to end-of-season influenza outbreaks.
- Later-in-the-season influenza immunisation may reduce outbreaks in such populations.