For the last 15 years, SHIVERS has tracked influenza and other respiratory viruses among thousands of volunteer New Zealanders and developed one of the world’s leading influenza longitudinal studies. Unlike traditional influenza surveillance, which focuses on people sick enough to seek medical care, SHIVERS captures comprehensive data on how influenza progresses from mild to severe disease and how our immune systems respond.  

WellKiwis, a Wellington‑based community cohort study, is a flagship of the SHIVERS programme. It uses weekly surveys and testing at the PHF Science laboratories to identify influenza and other respiratory viruses. The study also examines how the influenza virus spreads within households and how the first exposure to influenza, either through infection or vaccination, shapes a person’s immunity over time. 

Data from SHIVERS directly led to a major change in New Zealand’s influenza vaccination policy in 2013, where vaccines became free for children under five with a history of significant respiratory illness. The programme has also contributed to changes in the World Health Organization surveillance standards and is informing global efforts to create a universal flu vaccine.  

The SHIVERS studies play an essential role in strengthening New Zealand's preparedness for seasonal and future pandemics and have international relevance – often predicting Northern Hemisphere trends, helping shape early global responses to emerging viral threats.