A computer glitch has seen 11,000 coronavirus cases missed off the official count in Wales last week.
The figure for December 9 to 15 currently stands at 11,911, but this could double later today when the missing positive tests are added.
Public Health Wales has blamed the oversight on ‘planned maintenance’ of some IT systems, in an error that has hidden the full impact of Wales’ fire-break lockdown.
It is not the first time health chiefs have botched their figures, after Public Health England admitted in October it had missed 16,000 cases from the UK official tally due to an Excel spreadsheet blunder.
As many as 30,000 positive tests also had to be removed from the UK total in July, after PHE admitted it had ‘double-counted’ its figures.
A total of 103,098 people have tested positive in Wales since the pandemic began, meaning the 11,000 extra positives – which will be added PHW figures on Thursday – will represent roughly one tenth of the new total.
PHW says positive tests from Lighthouse laboratories, which were set up to process Covid-19 swabs, had not been added to its total.
A spokesman said a ‘very large backlog’ of cases, in the region of 11,000, would be added to their total when the figures are updated around 2pm.
Plaid Cymru’s health spokesman Rhun ap lorwerth told BBC Radio 4’s Today programme the blunder ‘raises questions about the way data is analysed’.
‘It raises questions again about the interaction between what is controlled in Wales and the Lighthouse laboratories, and it’s one of those things that again sort of rocks trust in what’s happening and the data that’s presented to us,’ he said.
‘I must say when the First Minister announced yesterday that from the 28th there would be a tightening of restrictions, and I could see the figures as they were, one wondered why not do things now in terms of stepping up support for areas most heavily affected, but this does put a new slant on it again.
He added: ‘This is a serious bulk of figures being added to the total today and it raises questions about the way data is analysed.’
Yesterday, it was reported that 30 more people had died with coronavirus in Wales and 530 more cases were announced.
It comes as cases continue to rise in the country with First Minister Mark Drakeford announcing a tightening of the Christmas bubbles rules and a third lockdown from December 28.
In a dramatic break with the UK-wide approach, Mr Drakeford will change the law so just two households can mix rather than three.
He also said the nation would go back into lockdown once the five-day Christmas relaxation of rules is over.
Wales currently has the highest infection rate in the UK – 425 per 100,000 people – with eight of the top ten worst-hit areas.
Mark Drakeford said today that Wales would be going back into lockdown once a relaxation of rules over Christmas comes to an end
Mr Drakeford said one in five people in Wales is testing positive for the virus, while more than 2,100 are in hospital with symptoms. A record 98 are in intensive care.
Wales only ended a 17-day ‘firebreak’ lockdown on November 8.
Mr Drakeford said new measures were necessary because the situation had become ‘so serious’. He stressed that the ‘sustained rise in coronavirus’ meant the country would go into its third lockdown from Monday December 28.
Non-essential shops and gyms will close earlier – on the evening of Christmas Eve – while all restaurants, pubs and bars will shut from 6pm on Christmas Day. From December 28, tighter rules will restrict household mixing, travel and holiday accommodation.
Mr Drakeford said Wales’s move into the fourth and highest level of restrictions would last for three weeks before being reviewed. He insisted: ‘The situation we are facing is extremely serious.
Non-essential shops and gyms will close earlier – on the evening of Christmas Eve – while all restaurants, pubs and bars will shut from 6pm on Christmas Day. From December 28, tighter rules will restrict household mixing, travel and holiday accommodation
Christmas advice has toughened up in Wales, with Mr Drakeford changing the law so that no more than two households can mix. He said: ‘A shorter Christmas is a safer Christmas’
‘We must move to alert level four and tighten the restrictions to control the spread of coronavirus and save lives.’
The First Minister also toughened up the Christmas advice, changing the law so that no more than two households can mix.
He said: ‘A shorter Christmas is a safer Christmas.’
The Welsh government later said that the guidance on two households would be enshrined in law.
Matthew Jones, clinical director for emergency care at the Prince of Wales hospital, told ITV that ambulances were queuing outside with patients.
He said: ‘With the ambulances outside like this, there’s a strong argument that we are beyond crisis point – that this isn’t safe.’