Nichols MK, et al. - The vaccine effectiveness (VE) of trivalent influenza vaccine (TIV) for preventing influenza-related hospitalizations and other serious outcomes over three consecutive influenza seasons was investigated (in adults ≥16 years of age) via analyzing data from the Serious Outcomes Surveillance (SOS) Network of the Canadian Immunization Research Network (CIRN). Year-to-year variability was reported in the effectiveness of TIV to prevent serious outcomes. Over three seasons, a statistically significant and clinically important TIV VE for preventing hospitalization and other serious outcomes was shown. The overall benefit of influenza vaccines over time should be highlighted by public health messaging while acknowledging year to year variability.