Association between vaccination coverage decline and influenza incidence rise among Italian elderly

After a peak of 68.3% during the 2005-06 season, influenza vaccine coverage among Italian elderly showed an unprecedented, prolonged decline. According to the National surveillance network, the vaccination coverage was ≤50% during two of the last three seasons (2014-17). In parallel, influenza-like illness (ILI) rates increased from 2.71% in the triennium 2005-08, to 4.24% in the last triennium. A significant association was found between ILI rise and vaccine coverage decline (P = 0.036), and according to a conservative estimation, each 1% increase in coverage may prevent ≥2690 ILI cases among the elderly. A reinforcement of influenza immunization policies is strongly needed in Italy.