How does the Covid-19 data blunder affect the battle against the virus?

A woman wearing a mask walks past a coronavirus sign
Almost 16,000 coronavirus cases were not recorded for several days. Credit: PA

An IT blunder has led to delays in tracing the contacts of people who have tested positive for Covid-19 after thousands of cases were missed last week.

Public Health England (PHE) said a technical issue resulted in 15,841 cases between September 25 and October 2 being left out of the reported daily coronavirus cases.

PHE said the “technical issue” was identified overnight on Friday and that all the missing data has been handed to NHS Test and Trace by 1am on Saturday.

However, this means there was up to a week in contacting thousands of infected people's contacts, potentially contributing to a spread of coronavirus cases in the UK.

Here’s what we know so far:

Why was there such a big leap in cases over the weekend?

According to official data there were 22,961 cases of coronavirus reported on Sunday and 12,872 reported on Saturday.

This compares to an average of around 7,000 cases reported in the four preceding days.

But it has emerged that the big leap in cases seen at the weekend occurred due to a “technical issue” which was found on Friday evening.

This glitch meant that 15,841 cases between September 25 and October 2 were left out of the reported daily coronavirus cases and were only added to the official statistics over the weekend, inflating the numbers.

Does this mean there has been a surge in coronavirus cases?

Yes and no, officials said that the data published on October 3 and 4 are “artificially high” – because it includes cases from as far back as September 25.

But last week already saw a high number of cases reported, so adding on the ones missed will make the numbers look even more alarming than before.

(PA Graphics) Credit: PA Graphics

Has the problem been sorted?

A note on the government’s coronavirus data dashboard says that the issue has been “resolved” and PHE has said that “further robust measures have been put in place as a result”.

The issue occurred because some files containing positive test results exceeded the maximum file size that takes these data files and loads then into central systems, officials said.

They said that “rapid mitigation” measures have been put in place to ensure the issue does not occur again.

Experts argue that a circuit-breaker could provide time for improvements to NHS Test and Trace to be made Credit: Scott D’Arcy/PA

Did it affect when people got their test results?

No. Officials from PHE and Test and Trace said that people who were tested received their Covid-19 test results in a “normal way”.

So were contacts of these positive cases reached and told to self-isolate?

As soon as the missing cases were reported, officials said that the information was “immediately” handed to NHS Test and Trace so contact tracing could begin and people in contact with those who had the virus were instructed to self isolate.

But this means it could have been up to six days between someone testing positive for the virus and their contacts being traced.

Will this have contributed to the spread of the virus?

There is no way of knowing the precise ramifications of the error because of the way the new coronavirus spreads.

Some people are asymptomatic carriers and will be infected without knowing, while others will show symptoms, including a loss or change in sense of smell or taste, a new and persistent cough and a fever.

If everyone followed the rules then hopefully as soon as someone became symptomatic they immediately began to self-isolate and even those who had no symptoms would have hopefully self-isolated upon getting their result.

A cyclist passes a Covid-19 test centre sign Credit: Andrew Milligan/PA

Do we know where in the country has been affected by the issue?

Information from health officials does not make clear where the newly reported cases come from in the country.

But officials have said that the missed data reporting “does not impact the basis on which decisions about local action were taken last week”.

So how many cases does this mean have been recorded in total?

The number of reported positive Covid-19 cases in the UK has now passed half a million, with the cases reported over the weekend tipping the positive cases over the 500,000 mark – 502,978 cases according to the Government’s coronavirus dashboard.