This is according to a study commissioned by Healthy Return, a back-to-work programme focused on employee testing for COVID-19.
The study asked HR directors and senior decision-makers what percentage of their workforce they planned to bring back at the first possible opportunity.
The majority of employers (32%) said they planned to bring back 30-40% of their employees as soon as possible.
Another substantial percentage (30%) said they planned to bring back 50-60%, while 22% of employers planned to bring back 70-80%.
Just 4% of employers said they only intended to bring back 10-20%, while 8% planned on bringing back 90-100% of employees at the first opportunity.
Dr Anshuman Bhagat, NHS GP and chief medical officer at GPDQ.co.uk, said: “As a health expert on the frontline, my main concern is that around 20% of the UK workforce currently have underlying health issues that, should they be asked to come back to work, could put them at an unacceptably high level of risk.
“There must be a clinical approach to bringing the right employees back to work safely.
“The only way to promote a risk-stratified return to work plan is to assess the state of health of the workforce, test employees before the return to work and then introduce a test and trace action plan once people are back to stop the spread.”
Ed Hussey, director of people solutions at accountancy firm Menzies LLP, also warned against bringing workers back without careful planning.
He told HR magazine: “Now is not the time to create tension by forcing people to act against their will.
“Listening, considering individual circumstances and showing flexibility will be crucial to ensuring businesses come out of this without permanent scars on their employee relations.”
Also speaking to HR Daniela Mazzarella, board member and head of engagement for the Professional Women's Network, added: “Although we are all keen to get back to ‘normal’, we must acknowledge employees have had to adapt to new routines and ways of living and working.
“They will now need to return to a life which may never feel the same or work arrangements which may no longer be as appealing.
“We must be mindful of the measures and support structure we are putting in place to promote a motivating, productive and psychologically safe return.
Both Hussey and Mazzarella echo legal experts’ statement that employers should not bring people back to work until they have preventative measures in place.
Their comments come as three-quarters of Britons say they would be “very nervous” about leaving their homes as lockdown lifts.
Hussey added: “Employers should communicate and engage constructively with their staff to identify those who are prepared to come back and those who are not.
“Recent changes to the Coronavirus Job Retention Scheme (CJRS) mean that it may well be possible to find some middle ground by enabling some workers to remain furloughed, while coming back to work part-time when this new flexibility is introduced from August.”
At present, the UK government has said it will extend the furlough scheme until October this year.
Healthy Return’s study, which was conducted between 5 and 8 May, surveyed HR directors and senior decision-makers responsible for over 52,000 UK-based employees.