Almost 16,000 cases of coronavirus in the UK went unreported because of a glitch caused by an Excel spreadsheet, it has been reported.
Public Health England (PHE) said 15,841 daily COVID-19 cases between 25 September and 2 October had been left out of UK totals.
The error has caused delays in tracking the contacts of people who tested positive.
On Monday, the Press Association (PA) news agency reported that the problem was caused by a Microsoft Excel spreadsheet reaching its maximum file size.
This prevented new names being added in an automated process, it said.
PA said files have now been split into smaller batches to prevent the error from happening again.
Previously, PHE said the issue was caused by some data files reporting positive test results exceeding the maximum file size.
Meanwhile, a government minister defended the error, saying: “We can’t change history”.
Watch: Minister unable to give number affected by glitch
Work and pensions secretary Thérèse Coffey told BBC1’s Breakfast programme she did not know how many potentially infectious contacts of COVID-19 patients were not traced because of the glitch.
“I’m afraid I just don’t have that information,” she said.
She also admitted that people may have been infected because the NHS Test and Trace scheme was not aware of the unreported cases.
Shadow health secretary Jonathan Ashworth said of the glitch: “This is shambolic and people across the country will be understandably alarmed.”
He called on health secretary Matt Hancock to go to the House of Commons on Monday and explain “what on earth has happened, what impact it has had on our ability to contain this virus and what he plans to do to fix test and trace”.
The glitch means the daily coronavirus totals published on the government’s COVID-19 dashboard in the past week have been lower than the real numbers.
The unreported numbers were included instead in Saturday and Sunday’s totals of 12,872 and 22,961 cases respectively.
A note on the government dashboard said: “The cases by publish date for 3 and 4 October include 15,841 additional cases with specimen dates between 25 September and 2 October – they are therefore artificially high for England and the UK.”
Michael Brodie, the interim chief executive at PHE, said the “technical issue” was identified overnight on Friday, 2 October, in the data load process that transfers COVID-19 positive lab results into reporting dashboards.
“NHS Test and Trace and PHE have worked to quickly resolve the issue and transferred all outstanding cases immediately into the NHS Test and Trace contact tracing system and I would like to thank contact tracing and health protection colleagues for their additional efforts over the weekend,” he said.
Watch: Why are UK deaths low despite cases rise?
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