Patients who tested positive for coronavirus were among 221 people discharged into care homes from hospitals in west Wales during the peak of the crisis.
Only 30 of the 221 patients discharged between the beginning of March to the middle of April were tested.
Hywel Dda University Health Board said 25 of the tests were negative and that five were positive.
The figures follow a Freedom of Information request by the Local Democracy Reporter Service.
The health board said the 30 patients tested were showing symptoms of the virus, and that it had been following the national guidance of the time.
In answer to a follow-up question about what steps were taken to ensure care homes receiving the five positive patients could look after them safely, a Hywel Dda spokesman said all discharges were "planned in partnership with the receiving care home to ensure arrangements were safe and met the needs of patients concerned and other residents".
Health boards and trusts throughout the UK were desperate to create extra hospital capacity as the pandemic took a grip in March. Families were encouraged to take their relatives home, while others were moved into care homes.
There were warning signs though from Europe, where Covid-19 began its rampage before the UK, that care homes were particularly susceptible.
Hywel Dda University Health Board said that on April 22 Wales' chief medical officer, Dr Frank Atherton, issued updated guidance for health boards to test all inpatients prior to discharge to a care home.
The Welsh Government has maintained that it was following the scientific advice throughout the crisis, although in mid-June Vaughan Gething, Minister for Health and Social Services, said he would have made “different choices” at a number of points during the pandemic.
Wales Online has reported that 713 people with coronavirus died in Welsh care homes up to June 5 - nearly a third of all the country's 2,317 deaths linked to Covid-19.
The virus could also get into care homes via staff, although many facilities took extraordinary steps to protect their residents.
One example was Erwhir Care Home, Carmarthen, where staff lived in the home for six weeks.
The care home's owner and manager, Aled Rees, said there were no vacancies during the peak of the pandemic and that it had thankfully not been affected to date.
"We said among the managers at the beginning that we were not going to take anybody in," said Mr Rees.
"We didn't care what pressure we might get. We didn't care about losing income.
"Our staff came into the home to live - that's six weeks of being deprived of their own families.
"They were so devoted to their job and the residents."
Mr Rees said he felt under pressure in normal times to accept people from hospital into the Long Acre Road home.
He claimed that on July 7 he was contacting a Carmarthenshire Council safeguarding team to authorise the return of a resident who had needed treatment in hospital when that patient arrived by ambulance at the home.
He said he had raised a complaint about it.
The Senedd's health, social care and sport committee said in a report this month that it was "deeply troubled" by the number of Covid-related deaths in care homes.
The committee said it felt the Welsh Government’s initial approach to testing in care homes was "flawed", and that it was subsequently too slow in responding to the crisis.
It took too long, said the committee, to implement appropriate testing measures for care homes.
Care home residents, it said, had been "badly let down".
The report said: "Moving forward, there is a need to be confident about the ongoing availability of tests for care home residents and staff, particularly as visitor restrictions are relaxed."
The Welsh Government said it didn't accept that care home residents had been badly let down.
"Our approach has been rooted in scientific evidence with the sole objective of saving lives, regardless of where people live," it said.
Mario Kreft, chairman of care representative group Care Forum Wales, said the number of care home deaths from Covid-19 was "shocking but sadly not surprising when you consider the NHS was so prioritised in the early days".
Social care, he claimed, was left behind.
Mr Kreft said: “Anecdotally, the message from our members is that it would appear admissions from hospitals have been a major factor in spreading the virus like wildfire in those care homes, as opposed to community transmission.
“A survey we conducted showed that 42% of care homes felt they had been pressurised into accepting hospital patients who were either Covid-19 positive or had not been tested."
Back in Carmarthenshire, care homes are getting ready to welcome back visiting relatives for the first time in months.
Safety and social distancing measures will be to the fore.
Visits at Erwhir Care Home are resuming, but only outside for now.
Mr Rees said he had bought pop-up gazebos to make the experience better for residents and their relatives.
Reflecting on the past four months, he said the stock of care workers had risen among society.
"I think people have seen how dedicated and hard-working people in the health and social care sector are," he said.
