Hundreds of people have been wrongly told they have coronavirus by NHS Test and Trace after a laboratory error.
More than 1,300 people who gave samples between 19 and 23 November received positive results, when the tests were actually void.
All of those affected will be told to take another test, the Department of Health and Social Care (DHSC) said.
Duncan Larcombe, whose daughter received the wrong result, said it was "more than an inconvenient mistake".
The PR company director, from Maidstone, Kent, said his two children, aged 14 and nine, were both sent home from school to self-isolate and he was unable to work.
He said his 14-year-old daughter had not left her bedroom for four days, with meals being left outside her door, until the family learned the result was void on Thursday.
"We were taking it very seriously," he said.
Mr Larcombe, a former royal editor at the Sun newspaper, said the mistake "brings into question for me whether or not this testing system is competent".
"The entire economy is relying on the competence of the testing laboratories and if they are not doing their job they need to be held to account," he said.
DHSC said it was an "isolated incident" caused by an "issue with a batch of testing chemicals" which had affected tests taken across the UK.
It is "being fully investigated to ensure this does not happen again," the department said.
Mr Larcombe's daughter has now received a negative result after taking a second test on Thursday.
"Given that [the government] have just decided to put the whole of Kent in tier 3, you just wonder, is their modelling flawed," he said.
Asked if the 1,311 incorrect results would affect regional figures for infection rates, which are represented as the number of cases per 100,000 people, DHSC issued a statement saying: "Any impact on regional figures would be minimal, but in any event this incident was taken into account when the tiering discussions took place."