The surge in the Indian Covid-19 variant was fuelled by failures in England’s test and trace system, a report has found.
Eight local authorities did not have access to the full data on positive tests in their areas for three weeks in April and May, it says.
The number of missing cases was highest in Blackburn with Darwen, in Lancashire – where a recent rise in infections was linked to the Indian variant.
The other areas affected by the apparent technical glitch were Blackpool, York, Bath and North East Somerset, Bristol, North Somerset, Southend-on-Sea and Thurrock, the BBC revealed.
Officials at one of the councils affected said the centralised test and trace system failed to notify its staff of cases, meaning their contacts could not be traced locally.
The “rapid spread of Indian variant cases … may be partially or largely attributable to risks in the international travel control system”, the report states.
But it adds: “These were exacerbated by the sporadic failure of the national test and trace system.”
Six of the local authorities affected told the BBC that they had experienced problems in tracing contacts.
Jonathan Ashworth, Labour’s shadow health secretary, seized on the revelation, saying: “This is deja vu and echoes the mistakes made last year with Boris Johnson’s ‘whack-a-mole’ approach.
“It beggars belief that yet again local health experts on ground have been left in the dark for two weeks when we know acting with speed is vital to containing an outbreak.
“Ministers need to explain what’s gone wrong and provide local health directors with all the resources they need to push infections down.”
But Mr Johnson’s spokesperson played down the impact of the problem, saying: “This issue was across a small number of local authority areas and was quickly resolved.”
Asked if the problem had helped the Indian variant spread, he said: “I don’t think it is possible to draw that conclusion from this.”
The government has continued to call the test and trace system “world-beating” – despite a parliamentary inquiry finding, in March, that it was making no “measurable difference”.
The MPs condemned an over-reliance on consultants paid up to £6,600 a day, a failure to meet the surge in demand for tests last September and never hitting a target to turn around face-to-face tests within 24 hours.
Contact tracers have consistently reported only having enough work to fill half their time, even when cases were rising.
Between 21 April and 11 May, the system only provided details of a limited number of positive cases of coronavirus to the eight local authorities, the BBC said.
On 11 May, they were told by the Department of Health and Social Care that, over that period, 734 positive tests had not been reported.
It meant that, in many cases, the councils were also unable to offer financial support to people isolating.
