Pre-vaccine shielding prevented thousands of COVID hospitalisations across England, study finds

This Foundation‑funded study, published last week in BMC Medicine, shows how similar strategies could play a role in preventing future outbreaks.

Coronavirus disease (COVID-19), caused by the SARS-CoV-2 virus, first emerged in 2020, triggering the World Health Organization to sound its highest level of global alert and declare a pandemic.

In the UK, the government identified people who were particularly vulnerable due to underlying health conditions, and advised them to self-isolate at home and avoid all non-essential face-to-face contact.

This policy, known as ‘shielding’, began on 22 March 2020. Across England, 2.25 million NHS patients were included in the ‘shielding’ population.

Today, thanks to global vaccination programmes, rates of COVID have fallen significantly. But even as we pass the six-year mark since the pandemic began, the shielding policy has still not been evaluated to determine whether it successfully protected people across the country – until now.

Professor Rosalind Eggo (LSHTM), Professor of Infectious Disease Dynamics and lead author of the study, explains, “Evaluating this policy’s impact required information on both infection risk and COVID-19 health outcomes for those eligible for shielding.

“To support this, we combined data from ‘CoMix’ - an online social contact survey in which UK participants recorded their awareness, attitudes and behaviours during the pandemic - with detailed data on hospitalisations and deaths from NHS health records.”

With approval from NHS England, Rosalind and her colleagues accessed electronic health records for 24 million patients across England through ‘OpenSAFELY’, a platform for analysing pseudonymised NHS data. They examined records from 1 January to 1 December 2020 - the first stage of the pandemic, before vaccinations were rolled out and before new variants emerged.

The team also used a dynamic transmission model to estimate how infection spread through the population, enabling them to infer the likelihood of severe outcomes in both shielding and non-shielding groups.

By comparing the observed pandemic to a hypothetical scenario without shielding, the team found that between 7,800-10,600 hospitalisations and 2,300-3,500 deaths due to COVID-19 were directly avoided by the policy. These numbers correspond to a 25% and 23% reduction, respectively, across England’s shielding population.

Across England’s whole population, the researchers estimate that the burden of severe illness and deaths was reduced by 11-15%, accounting for thousands of people, all due to this intervention.

“Shielding was a major policy that impacted a lot of people’s lives. We found that it substantially reduced severe COVID‑19 cases in the pandemic’s first nine months,” says Rosalind.

The study shows that the UK’s shielding policy significantly relieved pressures on the NHS. The intervention also helped to reduce severe illness and death in people who were more susceptible to infection from COVID-19, helping to keep our most vulnerable safe.

Looking forward, we know we need to apply learnings from this pandemic to future disease prevention, preparedness and response. Rosalind adds, “It’s important to understand the impact that shielding had on hospitalisations and deaths so that policymakers can decide whether it should be used again in future pandemics.”

Dr Angela Hind, Chief Executive of the Foundation, comments, “Throughout the COVID-19 pandemic, mathematical modelling was vital to decisions that affected us all.

“Professor Eggo’s recent work has provided invaluable insight into how the virus spread, how it was controlled, and what interventions are most likely to protect our communities in the future. Our donors can be deeply proud to have supported research that can inform national policy and helps the country prepare for further disease outbreaks and other major health threats.”

See the full study here >>