Apparently the U.K. was not undercounting COVID-19 cases in the country due issues with the Excel file format they were using.

According to the BBC, the error was caused by the fact that Public Health England developers stored the test results in the file format known as .XLS. These .XLS files were then sent to the NHS after uploading to a central system. .XLS is an outdated file format, however, and each spreadsheet can have only 65,000 rows. By contrast, the .XLSX file format, which was first released in 2007, allows for more than 1 million rows. Because of the limited number of rows, each spreadsheet could contain about 1,400 cases, leaving excess cases off the file altogether. Although the issue was reportedly fixed by splitting the files into smaller batches, many are slamming Public Health England. “Why are critical databases in a national pandemic posted on Excel spreadsheets?” Jonathan Ashworth, the Labour Party’s shadow health secretary, said. “Why aren’t they using specialist data-based software?”

Read the full article from Slate here. The article also gives some more examples of problems caused by using the spreadsheet software.