New study: No evidence that shielding reduced COVID-19 infections in Wales

A research team from Swansea University have been examining data from the year after the policy was introduced in March 2020, concluding that a “lack of clear impact on infection rates raises questions about the success of shielding.”  

Shielding was introduced to protect those thought to be at highest risk of serious harm should they catch COVID-19, for example because of preconditions such as cancer or medications that they were taking.  Key to protecting vulnerable people was to reduce their risk of contracting COVID-19.

The researchers examined the situation in Wales, but as shielding policy was similar across the UK, their findings will be of relevance in other countries too.    

Working with the NHS, they examined how shielding affected COVID-19 infections, deaths, and admissions to hospital and intensive care. They compared the 117,000 people shielding in Wales with the rest of the population - 3 million in total – who were not.   

The largest clinical categories in the shielded cohort were severe respiratory condition (35.5%), immunosuppressive therapy (25.9%) and cancer (18.6%) 

The team drew on data from anonymous electronic health records routinely collected for the entire Welsh population, which are held securely within the SAIL Databank at Swansea University. 

The researchers found that:  

• Deaths and healthcare utilisation were higher amongst shielded people than the general population, though this would be expected as they are sicker.  
• The known COVID-19 infection rate was also higher in the shielded cohort (5.9%) than in the general population (5.7%) 

The researchers conclude:   

“A 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.”  

Commenting on the policy context the authors say: 

“Shielding was an untested public health policy that was introduced in the United Kingdom early in the pandemic, in contrast to other countries where there was more focus on closing borders, lockdown, test and trace systems. The shielding policy was based on assumptions rather than evidence of effectiveness.”  

Professor Helen Snooks of Swansea University Medical School, who led the research, said:   

“Our study found no evidence of reduced COVID-19 infections one year after shielding was introduced. This raises questions about the benefits of shielding for vulnerable people as a policy.   

Work is ongoing to compare these outcomes, as well as self-reported quality of life, with a matched group of people who were clinically vulnerable, but not selected for Shielding. 

Having as much evidence as possible about the effect of policies is essential if we are to learn lessons for the future”.  

The project is known as EVITE Immunity, funded through the National Core Studies Immunity Programme - commissioned by Birmingham University on behalf of UKRI; and involves collaborations with Cardiff University, Warwick University, Welsh Government and NHS Wales.