A growing number of publications are recommending annual influenza vaccination of healthy children and adults. However, the long-term consequences of repeated influenza vaccination are unknown. We used a simple model of recurrent influenza infection to assess the likely impact of various repeated influenza vaccination scenarios.---
DISCUSSION
Under the plausible assumption that protection against influenza infection lasts longer after naturally acquired infection than after vaccination, we show that repeated vaccination at a young age substantially increases the risk of influenza in older age.---