Working while ill: Why a quietly sick workforce is a bigger risk than sick leave

Remote and hybrid working have done a huge amount of good for STEM businesses – wider talent pools, better flexibility and higher reported productivity. However, it has also created a quieter problem that leaders need to start addressing: employees who are working while ill, instead of taking time off to recover.

Not “sick leave”, but sick working

The data now supports what many of us in employment law have been seeing in real time – a shift from taking actual sick leave to “working from home” when feeling poorly.

CIPD’s Health & Wellbeing at Work report (2024/2025) notes that in organisations with home working:

• 36% report a fall in sickness absence BUT
• 35% report a rise in presenteeism — employees working while unwell.

In the private sector, particularly in technology, science, engineering and research, this trend is even more pronounced because work is portable. A developer can commit code from bed. A data scientist can push models from the sofa. A lab supervisor can clear inboxes from their phone.

The effect is what researchers call “virtual presenteeism” — showing up, just remotely.

ONS labour data shows sickness absence rates falling again in 2024, but that dataset only captures absence, not people working through illness. On the surface, that looks good but under the surface, there is at least the possibility that people are trading short-term availability for long-term performance.

Why this topic matters

For high-growth STEM organisations, productivity is everything. Lead time to product launch, customer implementation, clinical validation or funding milestones often depends on a small number of highly skilled individuals.

Deloitte’s Mental Health and Employers analysis (2024) estimates the UK annual cost of poor mental health at work at £51 billion, with almost half (£24 billion) attributable not to absence, but to people working while unwell.

The Institute for Public Policy Research (IPPR) recently estimated employees lose around 44 productive days a year due to working while ill — compared to 6–7 days lost through sickness absence.

Why STEM sectors are particularly exposed

STEM organisations have characteristics that unintentionally increase the risk:

If your business relies on key-person dependency, then presenteeism is not a wellbeing issue – it’s a single point of failure risk.

The legal risk: disability and long-term health conditions

From a legal perspective, businesses should remember:

• Working while ill can turn a short-term condition into a long-term disability
• Disability is a protected characteristic under the Equality Act 2010, meaning that special protection is given to workers who have a disability
• Amongst other things, that creates a legal obligation on the employer to make reasonable adjustments for those with a disability

In other words, allowing or encouraging employees to push through illness may not be the best way to manage your workforce in the long run.

What high-performing STEM employers do differently

The most effective businesses — and I see this in my own client base — do three things:

1. They make it explicit: working from home is not a substitute for sick leave. That one sentence gives employees permission.
2. They design for short-term absence. Process mapping is great for this. So, for example:

• If X is unwell today, can the business continue without friction?
• Do we have a buddy system / handover playbook / minimal client disruption plan?

3. They reward performance not presence. A culture that praises “never off sick” is inadvertently praising presenteeism. Recognition of output, collaboration and knowledge sharing is a much more positive way to engage staff.

How we can help

If you want to update your hybrid working or sickness absence policies to align your company with best practice, please get in touch.

Dawn Robertson, Partner & Accredited Specialist in Employment Law, BTO Solicitors LLP: dro@bto.co.uk / 0131 0131 222 3242