How do large-scale population studies inform vaccine evaluations in England?

Large-scale population studies are important to monitor and evaluate aspects of a vaccination programme including vaccine coverage, real-world effectiveness, and post-licensure vaccine safety. These types of epidemiological studies often come under the remit of public health agencies, such as the UK Health Security Agency (UKHSA) in England, which are required to undertake surveillance of vaccine-preventable diseases, including via seroepidemiological studies and data linkage studies using national-level electronic healthcare data. An individual-level national vaccine register with an accurate denominator can be the key to gaining insights into vaccine coverage, effectiveness, and safety. During the coronavirus disease 2019 pandemic, England's first vaccine register was developed. This enabled timely estimates of real-world vaccine effectiveness in the whole population of England, as well as enabling epidemiological investigations of rare potential risks from vaccines in specific populations. Population-based research studies, including prospective cohort studies, are complementary to surveillance and combined, enable more comprehensive assessments. As there was an unprecedented investment into research studies and infrastructure during the pandemic, the scale of these studies meant they were able to contribute to vaccine programme evaluations in a way that had not been possible for previous vaccine programmes. In this review, we summarise the different large-scale surveillance and research studies that have been used to evaluate and inform vaccine policy from the time of the first data linkage studies undertaken in England in the 1990s to the present-day post-COVID-19 pandemic.