The ‘Excel error’ that led to 16,000 missing coronavirus cases

A technical error with an Excel spreadsheet is believed to have caused 16,000 cases of coronavirus to be missed from national tallies, causing a “shambolic” delay to tracing efforts.

The issue occurred between September 25 and October 2, when testing data failed to transfer from the labs to the dashboards that report the numbers. 

Although the original numbers suggested the UK’s coronavirus cases were beginning to plateau, the missing cases instead confirmed the country’s number of positive test results is still on an upward trajectory. 

The error means on September 30, although the official daily tally showed 7,109 positive results, the total should have been 3,049 higher. On October 1, the total number of missing cases climbed to 4,133 and on October 2, that number was even higher, at 4,786. 

These 16,000 missing coronavirus extra cases have now been added to the official count. Although Public Health England said everyone who tested positive was informed in the normal way, those who came into contact with them were not.

Instead their details were passed to official contact tracers after the error was discovered, at 1am on Saturday, leaving the test and trace system facing a giant backlog of cases. 

What caused the IT error?

Public Health England’s interim chief executive Michael Brodie blamed the error on a “technical issue”, which he said was identified overnight on Friday, 2 October.

However, a report by PA suggests the fiasco was due to an Excel file containing lab results reaching its maximum file size, which stopped new names being added in an automated process. 

The files have now been split into smaller multiple files to prevent the issue happening again, the report claims. 

Matthew Parker, a mathematician and author of Humble Pi, tweeted: “When I first heard that cases were missing I thought “can’t be an Excel problem, the rows run out at 1,048,576 which is bigger than even total cases”.

“I never thought they’d have a case per COLUMN. Unbelievable. And yes: Excel columns end at 16,384 aka “XFD”.