As the 2025/2026 flu season saw an alarming number of cases earlier in the year than anticipated – triple the number of cases in October 2025 compared to October 2024 – the NHS was bracing itself for a busy flu season with the “superflu” doing the rounds. Since mid-December, however, things have started to look more positive as the numbers have steadily fallen. According to Health Secretary Wes Streeting, the NHS is “not out of the woods yet”, as flu cases have started to spike again after the festive season. 

With this in mind, it begs the question: how much do sick days affect UK businesses? Sadly, the flu season in particular costs UK companies a significant amount of money each year. It is estimated that sick days and related productivity losses during flu season cost companies around £272 per infected employee. While this may not sound substantial, it adds up to a total of around £644 million annually, with some reports suggesting it could be as high as £1.1 billion.  

Key Statistics

Let us look at some of the key statistics when it comes to sick days and how much it costs UK businesses, according to the latest figures: 

  • Lost working days: RAND Europe estimated that as many as 4.8 million working days are lost yearly in the UK due to flu alone. This number was calculated by examining the working-age population (18-64 years) over the last four flu seasons, including those who had the flu or were caring for a dependent with the flu. 
  • Cost per employee: As mentioned earlier, the estimated cost to companies is approximately £272 per infected worker during the flu season. Flu falls under general short-term sickness, which reports by MetLife UK indicate costs companies on average around £13,800 per employee. This cost covers both direct and indirect expenses, including temporary staff and administration, as well as indirect costs such as lost output and the additional workload imposed on staff who work with the sick employee.  
  • Annual cost: The estimated figure for flu-specific cases in recent reports is around £644 million a year.  
  • Hidden cost: One of the hidden costs is presenteeism – when an employee still comes to work while sick, thus affecting their output. This figure looks at all illnesses, not just flu, and is estimated to cost the UK economy nearly £28 billion per year.  

Key Determinants Influencing Cost

For the 2025/26 tax year, the Statutory Sick Pay (SSP) is £118.75 per week, but the cost of sickness also includes indirect costs that influence overall costs: 

  • Work output: When an employee is unable to work, it greatly reduces work output.
  • Temp staff: If an employee is unable to work for a longer period, companies often resort to temporary staff, which costs the company extra time and money, as they still have to train the temporary staff to cover the workload. 
  • Lowered morale: The increased pressure and additional workload placed on other employees can result in reduced morale, which may subsequently impact their overall work performance.
  • Presenteeism: As previously noted, presenteeism has a significant impact on productivity. Although employees may be physically present at work, few companies recognise the associated costs – yet businesses lose billions of pounds every year as a result. 

Is Your Business Prepared for The Flu Season?

It is noteworthy that numerous businesses fail to monitor the financial consequences associated with employee sickness absence. And while people have, in a way, accepted that flu is just part of life, it doesn’t have to be. With the help of FluClinic2You, you can reduce the risk of flu spreading in the workplace by making flu vaccinations part of your yearly health plan. Contact our team at FluClinc2You to discuss how we can help your business be prepared for the flu season with our on-site corporate flu vaccination programme.