The UK government has been embarrassed by its key monitoring agency under-reporting COVID-19 infections thanks to a misconfigured Excel spreadsheet.

Over the weekend it was revealed Public Health England, the government agency responsible for community and public health services across England, had missed 15,841 COVID-19 cases between September 25 and October 2.

The undercount was due to the agency saving its file in the outdated .xls file version of Microsoft Excel capable of saving just over 65,000 rows instead of using the .xlsx version that can handle up to 1,048,576 rows.

Excel’s .xls file version was superseded with Microsoft’s release of Office 2007 in late 2006.

Public Health England’s mistake meant there were eight days of incomplete data over a period where there was a daily average of 6,273 new cases being reported.

The mistake meant cases were not being passed onto the National Health Service’s track and trace team, leaving the contact tracers scrambling to cover the backlog.

According to The Guardian, UK Health Minister Matt Hancock told the House of Commons, “This incident should never have happened. The team have acted swiftly to minimise its impact and now it is critical that we work together to put this right, and to make sure that it never happens again.”

Spreadsheets like Excel have long caused data handling problems due to errors in cutting-and-pasting, formatting, formula errors, and the hiding of rows.

British institutions have been particularly prone to expensive and embarrassing Excel mistakes. In 2012, errors in a UK based analyst’s spreadsheets were partly blamed for JP Morgan’s London Whale debacle that cost the bank over US$6.2bn.

In the same year, the London Olympics Organising Committee oversold tickets to its swimming finals due to a staff member entering the wrong number into a spreadsheet.

Two years earlier, MI5 bugged over a hundred incorrect numbers due to a misconfigured spreadsheet and in 2008, Barclays Capital inadvertently bought 179 worthless contracts from the bankrupt Lehmann Brothers due to an Excel formatting error.

The errors though are not limited to British users, with one survey claiming up to 88% of Excel spreadsheets contain some sort of error.

For the current problem in the UK, Public Health England has solved the problem by breaking down the errant spreadsheet into smaller sheets as an interim measure.

However, the UK debacle shows the importance of using the right data tools while making sure up-to-date software is used.