Seven ways the SHIVERS programme changed how the world manages viruses

For 15 years, New Zealand has led an influenza research programme of international importance. The SHIVERS (Southern Hemisphere Influenza and Vaccine Effectiveness Research and Surveillance) research initiative, hosted at PHF Science, has shaped both global and national health policy. It has contributed to revision of World Health Organisation (WHO) standards and frameworks, prompted major changes to New Zealand's vaccination policy, and provided important insights during the Covid-19 pandemic.

The research has tracked flu and Covid-19 among thousands of volunteer New Zealanders over multiple years. Unlike traditional influenza surveillance that only collects data about people sick enough to visit a doctor or hospital, SHIVERS also captures mild disease. Its longitudinal, community-cohort and hospital-based surveillance approach reveals the full burden of disease caused by respiratory viruses, providing important information for New Zealand's preparedness for seasonal viruses and future pandemics.

SHIVERS has now entered its sixth phase of research, bringing the total international funding it has received to over $62 million. Below, we highlight seven ways the programme has shifted how the world manages respiratory viral infections.

1. Flu vaccines are now free in New Zealand for children under five who have been hospitalised or have a history of significant respiratory illness. This major change in New Zealand's vaccination policy in 2013 was based on SHIVERS-I, which demonstrated high hospitalisation rates and low vaccination rates among children, and indicated that high-risk groups need better vaccination coverage.
2. Influenza surveillance standards in 194 countries were aligned after SHIVERS-I revealed that cases of the flu were being missed. The study found a reasonable proportion of people still test positive for influenza 8–9 days after symptom onset, not just 7 days as previously thought, prompting WHO to revise its global influenza surveillance standard in 2014. Now that all WHO member countries use the same “onset within 10 days” standard, rates of infection can be compared internationally, improving pandemic preparedness and monitoring. 
3. WHO’s global Pandemic Influenza Severity Assessment framework for making better pandemic response decisions used three indicators to measure virus transmissibility, disease seriousness and impact on healthcare. The high-quality data of SHIVERS-I contributed to the development of this important framework for global pandemic preparedness and response.
4. A national surveillance platform for respiratory diseases was established in New Zealand as a result of SHIVERS-I. It became essential national infrastructure and supported emergency pandemic response. New Zealand’s weekly surveillance data is provided to our Ministry of Health and National Public Health Service, and shared with researchers around the world to inform health policy, seasonal influenza control and pandemic response.
5. A universal flu vaccine may be possible in future, following the SHIVERS-I discovery that people have more anti-neuraminidase (NA) antibodies than anti-hemagglutinin (HA) antibodies. This surprising discovery in 2015 raised the possibility of tapping into the beneficial effect of NA for influenza vaccine development, in addition to HA, which could enable vaccines to be longer-lasting and more broadly protective. Universal flu vaccine research and clinical trials are currently underway in the US.
6. Public health measures were associated with a significant reduction in respiratory disease transmission. SHIVERS-II, III and IV were underway before the Covid-19 pandemic, so the data captured the effect of rare public health measures, including lockdowns and border closures. The absence of flu and RSV when these measures were in place provided evidence of their effect on respiratory disease transmission.
7. Covid-19 vaccination was highly effective in reducing community transmission. SHIVERS-II, III and IV were valuable to evaluate the impact of vaccination in New Zealand, informing future vaccine roll-out, equity, policy and public health communication. 

With more than a decade of rich data collected, SHIVERS continues to provide opportunities for researchers to build knowledge about virus transmission and immunity. “SHIVERS has resulted in significant change in the way how we understand immune response to influenza virus,” says Professor Sue Huang, principal investigator for SHIVERS and director of the WHO National Influenza Centre at PHF Science.

The recently funded sixth phase of SHIVERS focuses on New Zealand's unique two-year absence of influenza during 2020–2021 to understand how this immunity gap affects subsequent flu transmission and severity.

The platform's ability to pivot rapidly (as it did from influenza to Covid-19 in 2020) and research capabilities (including genomic sub-typing that can rapidly detect emerging strains like H5 bird flu) mean New Zealand is well-placed to respond rapidly to future pandemic threats.

The research continues through to 2029 with current US funding, but Huang emphasises: “For New Zealand to be safe, we need to maintain surveillance long-term. Community-level and hospital-based surveillance data is fundamentally important for New Zealand to be prepared for future pandemic responses.”