- Nine studies provided data for meta-analysis (n = 40,685 participants).
- Current smokers were 5 times more likely to have laboratory-confirmed influenza than non-smokers.
- Current smokers were 34% more likely to develop an influenza-like illness than non-smokers.
The association of current smoking with influenza infection is not widely recognised. The aim of this systematic review was to summarise published evidence and quantify the risk of influenza infection in tobacco smokers compared to non-smokers.