The effectiveness of seasonal trivalent inactivated influenza vaccine in preventing influenza hospitalisations and primary care visits in Auckland, New Zealand in 2013: provisional results

We present provisional estimates of influenza vaccine effectiveness (VE) for the NZ 2013 season. A case test-negative study was used to estimate propensity adjusted vaccine effectiveness. Influenza vaccination provided 52% (95% confidence interval (CI): 27% to 68%) protection against laboratory-confirmed influenza hospitalisation and 53% (95% CI: 28% to 70%) against laboratory-confirmed influenza in patients presenting to general practice.