Recovered Covid patients are being moved to care homes in England without needing a negative test under government policy.
Hospitals have been told they can discharge some patients straight to social care if they have no new symptoms or exposure.
That is despite the fact all other hospital patients need to have a negative test result within 48 hours of any move to a care home.
The Department of Health last night insisted it was “completely false” to claim infectious people would be moved into care homes.
But Labour claimed “this is history repeating itself with potentially tragic consequences yet again”.
Shadow Health Secretary Jonathan Ashworth said: “Having failed to protect care homes in the first wave, it appears ministers simply have not learnt the lessons.
“We urge ministers to review this guidance and ensure that no one is discharged into a care home without a Covid test, to protect lives.”
It is widely believed the virus was “seeded” into care homes during the first wave in a rush to discharge people from hospitals.
More than 20,000 deaths involving coronavirus were recorded in care homes in England and Wales last year.
The rule emerged in government guidance which was updated yesterday but has existed in some form since last month.
The guidance says hospitals must undertake a full, lab-based Covid-19 test on “all people discharged into a care home” within their final 48 hours on a ward.
But there is “an exception to this process” for some people who began suffering Covid-19 within the last 90 days, then recovered.
If they have “already completed their 14-day isolation” since symptoms began, and have no new “symptoms or exposure”, the requirement for a test before they leave hospital is waived.
The guidance says: “They are not considered to pose an infection risk.
“They therefore do not have to be re-tested and can move directly to a care home from hospital.”
This is despite a separate study today suggesting recovered Covid-19 sufferers may still be able to carry and transmit the virus.
Public Health England found antibodies from past infection provide 83% protection against reinfection for at least five months.
But Professor Susan Hopkins, senior medical adviser at PHE and the Siren study lead, added: “Crucially, we believe people may still be able to pass the virus on.”
The NHS expects all England’s elderly care home residents all be offered a vaccine by January 24.
However, it takes some weeks for initial protection to kick in, and second doses of the vaccine are only due after 12 weeks.
Hospital patients who test positive for Covid-19 in their final 48 hours of their stay are not moved into care homes.
Instead, they should be “discharged into designated settings” to isolate.
But data from the Care Quality Commission (CQC) shows that more than a third of local authorities in England had no approved ‘designated setting’ as of January 5.
Health officials said the policy was in place because a person can test positive for up to 90 days after first contracting the virus, but is “extremely unlikely” to be infectious beyond 14.
A Department of Health and Social Care spokesman said: “This guidance was published almost a month ago and approved by our deputy chief medical officers and Public Health England.
“Our priority is to ensure everyone receives the right care, in the right place at the right time.
“We have been doing everything we can to protect care homes since the start of the pandemic providing billions of pounds of additional funding, free PPE, infection control guidance, increasing staff testing and providing priority vaccines.”