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 linked data retrospective study.

INTRODUCTION: The UK shielding policy intended to protect people at the 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 23 March to 21 May 2020; and the rest of the population. Health records were extracted with event dates between 23 March 2020 and 22 March 2021 for the comparator cohort and from the date of inclusion until 1 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 years, living in relatively deprived areas, care home residents and frail. The proportion of people tested for COVID-19 was higher in the shielded cohort (odds ratio [OR] 1.616; 95% confidence interval [CI] 1.597-1.637), with lower positivity rate incident rate ratios 0.716 (95% CI 0.697-0.736). The known infection rate was higher in the shielded cohort (5.9% vs 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.

Effects of ingested fluids on exercise capacity and on cardiovascular and metabolic responses to prolonged exercise in man.

It is well established that the ingestion of carbohydrate-containing drinks can improve the performance of prolonged exercise. The present study examined the effects of ingestion of water and two dilute glucose-electrolyte drinks on exercise performance and on cardiovascular and metabolic responses to exercise. Twelve subjects exercised to exhaustion on a cycle ergometer at a workload corresponding to 70% of maximum oxygen uptake (VO2,max) on five occasions each separated by 1 week. The first trial served to accustom subjects to experimental conditions. On one trial, no drinks were given and on the others subjects drank 100 ml every 10 min. Drinks consisted of water, an isotonic glucose-electrolyte solution (I: 200 mmol/l glucose; 35 mmol/l NA2; 310 mosmol/kg) and a hypotonic glucose-electrolyte solution (H: 90 mmol/l glucose; 60 mmol/l Na+; 240 mosmol/kg). Treatment order was randomized. Blood and expired air samples were taken and heart rate and rectal temperature measured at intervals during exercise. Median exercise time was greatest for treatment H (110.3 min) followed by treatment I (107.3 min), water (93.1) and no drink (80.7). Endurance times differed significantly overall, and for pairwise comparisons (P < 0.01) between the no-drink trial and both treatments H and I: a difference between water and no drink was seen at the 5% level. At exhaustion, a significant treatment difference was found for the change in plasma volume, with the greatest decrease (6.7%) on the no-drink trial and the smallest decrease (0.5%) on treatment H. Significant treatment effects were also observed for heart rate, rectal temperature and serum osmolality. The results suggest that the ingestion of glucose-electrolyte drinks can improve exercise performance even when the amount of added glucose is small, and that performance may also be enhanced, albeit to a lesser degree, by ingestion of water.