In a recent retrospective study published in the Public Health Journal, researchers evaluated the effects of the United Kingdom's (UK) shielding policy intervention among residents of Wales at 12 months.

Study: 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. Image Credit: Alonafoto/Shutterstock.com

Background

It is known that older individuals with pre-existing comorbidities, including respiratory diseases, cardiovascular diseases, immunodeficiencies, diabetes, and malignancies, are at an increased risk of coronavirus disease 2019 (COVID-19) severity outcomes than other individuals.

In response to increasing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission and deaths due to COVID-19, the United Kingdom government introduced a national-level intervention called 'shielding' to protect individuals against severe COVID-19.

About the study

In the present study, researchers assessed COVID-19 testing rates and outcomes among shielded high-risk individuals and the unshielded public in Wales after 12 months of policy implementation.

The team retrospectively compared linked clinical and demographic data, including SARS-CoV-2 testing reports, the utilization of healthcare resources, and COVID-19-associated deaths, for EVITE Immunity study cohorts comprising individuals identified to require shielding between March 23 and May 21, 2020.

This formed the shielded cohort, and the remaining general public formed the unshielded comparator cohort. The C20 study group was formed to provide population-scale electronic health records data and facilitate the assessment of the effects of COVID-19 in Wales.

The C20 group comprised >3.20 million Welsch individuals residing in the country on January 1, 2020, or individuals moving into or taking birth there after the date. Individuals to be shielded were tagged in the C20 group.

The team retrieved medical records concerning health events from March 23, 2020, and March 22, 2021, for comparator group individuals and from the study inclusion date up to 12 months following policy implementation for the shielded group individuals.

The team obtained data from the secure anonymized information linkage (SAIL) databank. Data sources included the Annual District Death Extract (ADDE); the Patient Episode Database for Wales (PEDW); the Welsh Longitudinal General Practice Dataset (WLGP); COVID-19 pathology data; the Annual District Death Daily; the Consolidated Death Data; and the Critical Care Dataset.

The study outcomes included SARS-CoV-2 infection tests, positive SARS-CoV-2 infection test results, all-cause, and COVID-19-associated mortality; emergency department (ED) attendance; emergency hospitalization and hospital length of stay; intensive care unit (ICU) admissions and days in ICU; and common mental disorder (CMD) indicators.

Generalized linear modeling was performed, and the odds ratios (OR) and incident rate ratios (IRR) were determined, adjusting for sex and age. Deprivation was determined using the 2019 Welsh Index of Multiple Deprivation (WIMD 2019), and frailty was determined using the Electronic Frailty Index (eFI) scores, calculated on March 23, 2020.

Results

Of the 193,815 individuals initially eligible for shielding, 117,415 individuals identified during the first two phases of policy implementation, between March 23 and May 21, 2020, and linked to the C20 cohort comprised the shielded group and 3,086,385 individuals comprised the comparator group.

Most individuals in the shielded group suffered from severe respiratory conditions (36%), immunosuppressive therapies (26%), or malignancies (19%). The shielded individuals had a greater probability of being female (54% vs.50%), aged 50.0 years or above (80% vs. 39%), residing in regions with relatively high deprivation (43% vs.41% considering upper limits), residing in care homes (0.90 vs. 0.50%), and being severely frail (58% vs. 15%) than the comparator cohort.

The percentage of individuals who underwent SARS-CoV-2 testing was greater among shielded individuals (OR 1.6), with lower rates of SARS-CoV-2 positivity (IRR 0.7). The rate of infections was also greater among shielded individuals (5.90%) than in the comparator cohort (5.70%).

In addition, shielded individuals showed a greater likelihood of death (OR 3.7), critical care hospitalization (OR 3.3), hospital emergencies (OR 2.9), emergency department (ED) attendance (OR 1.9), and CMDs (OR 1.8).

A greater proportion of shielded individuals could have undergone SARS-CoV-2 testing despite a lack of COVID-19 symptoms, e.g., to meet routine care hospitalization requirements or due to anxiety. Alternately, shielded individuals with comorbidities such as chronic obstructive pulmonary disease (COPD) could have an increased likelihood of experiencing symptoms, increasing SARS-CoV-2 testing.

Moreover, the availability of COVID-19 testing facilities varied geographically and across the study period. Thus, the rates of SARS-CoV-2 infection were estimated to range between 5.9% and 16% among shielded individuals and between 5.7% and 19% among non-shielded individuals.

Despite efforts to shield high-risk individuals, the vulnerable population could have been exposed to SARS-CoV-2-positive individuals at their homes, in care homes, hospitals, or other care facilities and, therefore, be prone to COVID-19-associated complications.

The elevated rates of any-cause deaths and health resource utilization in the shielded cohort could be due to greater illness levels among shielded individuals, with differences not attributed to the shielding intervention.

Conclusions

Overall, the study findings showed that mortality and the utilization of healthcare resources were greater among shielded individuals than the general public, as expected for ill individuals.

Women aged ≥50.0 years, residing in highly deprived areas, and those with high frailty had an increased likelihood of being shielded. Discrepancies in the rates of COVID-19 testing, pre-existing health conditions, and deprivation were identified as potential confounders.

However, the impact on SARS-CoV-2 infection rates could not be well characterized, raising doubts concerning the success of shielding and warranting further research, including matched comparator groups, self-documented outcomes, and costs, for a thorough assessment of the national health policy intervention.

Caution must be exercised before implementing the policy in future pandemics until further scientific evidence is available concerning the benefit, harm, and cost of shielding.

Written by

Pooja Toshniwal Paharia

Dr. based clinical-radiological diagnosis and management of oral lesions and conditions and associated maxillofacial disorders.