Outbreaks of Covid-19 in care homes have more than trebled in a month, with levels of infections now similar to the peak of the first wave, figures show.
The latest surveillance data from Public Health England (PHE) reveals that, in the week to January 14, there was the second highest weekly total since records began in April.
On Thursday night, senior figures said the numbers were "shocking" and warned: "Care homes cannot be neglected again."
It came as the Government closed Britain's borders to Portugal and South America amid fears over a new strain of the virus from Brazil.
Ministers had pledged that all care home residents would be vaccinated by the end of this month, but The Telegraph has been told the care home rollout is taking longer than the Government had anticipated. Sources said only 100 residents could be vaccinated in the time it took to administer jabs to 1,000 people in the community.
On Thursday night, PHE said more than one third of people aged over 80 in England had been vaccinated, accounting for 56 per cent of the 2,371,407 vaccinations given up to January 10.
Matt Hancock, the Health Secretary, has said 25 per cent of older care home residents have received the jab, up from the previous figure of 10 per cent cited by Boris Johnson last week.
The new figures come after The Telegraph revealed that the Government is proposing to send hospital patients into care homes without tests despite being warned that was responsible for driving up cases in the first wave.
Telegraph analysis of official data shows that nearly as many patients caught Covid in England's hospitals during the last month as over the previous four combined. There is also concern that testing in care homes is failing to identify outbreaks.
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On Thursday night, it was reported that the Medicines and Healthcare products Regulatory Agency (MHRA) has warned the Government against the use in schools of lateral flow tests for Covid.
The same tests are currently being used in care homes, and experts have repeatedly raised concerns that they are unreliable.
The new PHE data shows that most outbreaks are now taking place in care homes, and that in the week to January 14 there were 977 outbreaks of respiratory conditions in care homes in England, of which 739 were confirmed as coronavirus.
That marks a stark rise since the week ending December 17, when just 305 outbreaks occurred, with 227 confirmations, and is closer to figures from mid-April, when 1,239 care homes reported outbreaks, with 651 confirmed.
Mike Padgham, the chairman of the Independent Care Group, said: "It's shocking to see these figures. It's great that we've got vaccines, but they've come too slowly. In Scotland, they found a way to get them into care homes more quickly than we did in England. We could have avoided this."
Adam Briggs, a senior fellow at The Health Foundation, said: "The rise in reported care home incidents is deeply concerning. Care homes cannot be neglected again."
The first wave was marked by the failure of officials to protect care homes, and the Government is anxious to avoid a repeat. Care home residents were identified as a priority in the vaccine rollout, but the inoculation of those in homes has proved trickier than ministers expected.
A senior source said: "It takes, on average, 10 hours to vaccinate a care home of 70 residents and 30 staff, whereas a team can vaccinate 1,000 people in the same time in a GP practice.
"It can obviously take a while to persuade some residents to have the vaccine or get them ready. It can involve going to their rooms rather than people coming to the vaccinator."
Many care homes are facing major staffing crises because of Covid and employees needing to stay at home to look after children.
Nadra Ahmed, who chairs the National Care Association, urged the Government to release data on how many care home residents and staff had been vaccinated, saying: "We need specifics."
Professor Martin Green, of Care England, said: "These worrying figures show that a vaccine alone is not a silver bullet."
A Department of Health and Social Care spokesman said: "We have been doing everything we can to protect care homes and have placed residents and staff in the highest priority group for vaccinations."
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