Nearly 16,000 coronavirus cases have not entered the national computer system used for official data due to a technical problem, Public Health England says.
Some of the unreported cases were then added to Saturday̵
He said all cases “received the Covid-19 test result as normal”.
BBC Health editor Hugh Pym said it meant that contacts from those who tested positive had not been contacted.
Public Health England said the cases were ignored from daily reports between September 25 and October 2.
He added that the IT problem had been resolved and all cases had now been transferred to the test and tracking system.
Labor shadow health secretary Jonathan Ashworth said: “This is chaotic and people across the country will understandably be alarmed.
“(Secretary of Health) Matt Hancock is expected to come to the House of Commons on Monday to explain what the hell happened, what impact it has had on our ability to contain this virus and what he plans to do to correct testing and tracking.”
Earlier, Prime Minister Boris Johnson warned it could be “patchy until Christmas” and beyond as the UK deals with the coronavirus.
Speaking with Andrew Marr of the BBC, the prime minister said there was “hope” in beating Covid and called on the public to “act without fear but with common sense.”
At a time when the test system has come under close scrutiny after reports of delays and a system struggling to keep up with demand, the latest revelation could not have come at a more embarrassing time for the government of Westminster.
Since the nearly 16,000 extra positive test results were not fed into the testing and tracking system, their recent contacts were not immediately followed up.
Experts advise that contacts should ideally be traced within 48 hours.
Officials say the glitch, thought to be IT-related, has been resolved, with all new cases added to the totals reported over the weekend.
But all of this is unlikely to improve public confidence in the test system in England.
And it muddies the waters for policy makers and officials trying to monitor the spread of the virus at what the prime minister called a “critical moment.”
On Sunday, a note on the government’s coronavirus dashboard said: “Cases by publication date for October 3 and 4 include 15,841 additional cases with sample dates between September 25 and October 2 – therefore artificially high for England and the United Kingdom. United “.
Public Health England’s interim chief executive Michael Brodie said that a “glitch” was identified on Friday, Oct.2 during the data upload process that transfers Covid-19 positive lab results into reporting dashboards.
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“After a quick investigation, we identified that 15,841 cases between September 25 and October 2 were not included in the daily reported Covid-19 cases. Most of these cases have occurred in the past few days,” he said.
“Each of these cases received the Covid-19 test result as normal and all those who tested positive were asked to isolate themselves.”
He said they worked with NHS Test and Trace to “quickly fix the problem and immediately moved all pending cases into the NHS Test and Trace contact tracing system.”
“We fully understand the concern this could cause and further robust measures have been put in place as a result,” he said.
Susan Hopkins, joint medical consultant for Test and Trace and Public Health England, added that “a thorough public health risk assessment was undertaken to ensure that pending cases were prioritized for effective contact tracing.”
A spokesperson for the Department of Health previously said that the problem did not affect the people who received the test results, and anyone who tested positive was informed in a normal way.
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