Did the UK's public health Shielding policy protect the clinically extremely vulnerable during the Covid-19 pandemic in Wales? Results of EVITE Immunity, a link data retrospective study

Introduction The UK shielding policy intended to protect people at highest risk of harm from COVID-19 infection. We aimed to describe intervention effects in Wales at 1 year. Methods Retrospective comparison of linked demographic and clinical data for cohorts comprising people identified for shielding from 23rd March to 21st May 2020; and the rest of the population. Health records were extracted with event dates between 23rd March 2020 and 22nd March 2021 for the comparator cohort and from the date of inclusion until one year later for the shielded cohort. Results The shielded cohort included 117,415 people, with 3,086,385 in the comparator cohort. The largest clinical categories in the shielded cohort were severe respiratory condition (35.5%), immunosuppressive therapy (25.9%) and cancer (18.6%). People in the shielded cohort were more likely to be female, aged >= 50, living in relatively deprived areas, care home residents and frail. The proportion of people tested for COVID-19 was higher in the shielded cohort (OR 1.616; 95% CI 1.597 -1.637), with lower positivity rate IRR 0.716 (95% CI 0.697 – 0.736). The known infection rate was higher in the shielded cohort (5.9% versus 5.7%). People in the shielded cohort were more likely to die (OR 3.683; 95% CI: 3.583 – 3.786); have a critical care admission (OR 3.339; 95% CI: 3.111 – 3.583), hospital emergency admission (OR 2.883; 95% CI: 2.837 – 2.930), Emergency Department attendance (OR 1.893; 95% CI: 1.867 – 1.919) and Common Mental Disorder (OR 1.762; 95% CI: 1.735 – 1.789). Conclusion Deaths and healthcare utilisation were higher amongst shielded people than the general population, as would be expected in the sicker population. Differences in testing rates, deprivation and pre-existing health are potential confounders, however lack of clear impact on infection rates raises questions about the success of shielding and indicates that further research is required to fully evaluate this national policy intervention

Evaluation of the shielding initiative in Wales (EVITE Immunity): protocol for a quasiexperimental study

Introduction: Shielding aimed to protect those predicted to be at highest risk from COVID-19 and was uniquely implemented in the UK during the COVID-19 pandemic. Clinically extremely vulnerable people identified through algorithms and screening of routine National Health Service (NHS) data were individually and strongly advised to stay at home and strictly self-isolate even from others in their household. This study will generate a logic model of the intervention and evaluate the effects and costs of shielding to inform policy development and delivery during future pandemics. Methods and analysis: This is a quasiexperimental study undertaken in Wales where records for people who were identified for shielding were already anonymously linked into integrated data systems for public health decision-making. We will: interview policy-makers to understand rationale for shielding advice to inform analysis and interpretation of results; use anonymised individual-level data to select people identified for shielding advice in March 2020 and a matched cohort, from routine electronic health data sources, to compare outcomes; survey a stratified random sample of each group about activities and quality of life at 12 months; use routine and newly collected blood data to assess immunity; interview people who were identified for shielding and their carers and NHS staff who delivered healthcare during shielding, to explore compliance and experiences; collect healthcare resource use data to calculate implementation costs and cost–consequences. Our team includes people who were shielding, who used their experience to help design and deliver this study. Ethics and dissemination: The study has received approval from the Newcastle North Tyneside 2 Research Ethics Committee (IRAS 295050). We will disseminate results directly to UK government policy-makers, publish in peer-reviewed journals, present at scientific and policy conferences and share accessible summaries of results online and through public and patient networks