More than 200 patients caught coronavirus while in hospital in the last week alone, it has been revealed.
Latest figures from Public Health Wales for the week ending November 22 show that 144 patients were "definitely" infected in hospital settings, while a further 59 were "probably" infected in hospital to bring the total to 203.
Swansea Bay University Health Board recorded the most probable or definite hospital-acquired infections over the seven-day period with 49, followed by Hywel Dda UHB with 42 and Cwm Taf Morgannwg UHB with 32.
A higher rate of Covid-19 circulating in hospitals inevitably translates to more deaths as many of the patients requiring care are older, more vulnerable, have a range of chronic conditions or are taking up beds in intensive care.
The overall Wales total of 203 was a drop on the figures for the week ending November 15 (269), November 8 (214) and November 1 (222). This can be attributed to several health boards recording a decrease in cases over recent weeks, including most notably Cwm Taf Morgannwg UHB which was recording as many as 84 cases over seven days at the start of November.
However, even in the middle of September there were barely a dozen (13 for the week ending September 13) patients recorded as catching the virus in hospital, with rates appearing to shoot upwards in the middle of October (from 59 to 103 between October 4 and 11) and into November.
Former ONS statistician Jamie Jenkins said: "Over the past 11 weeks there have been 1,503 patients who, according to Public Health Wales, have definitely or probably caught Covid-19 in hospital.
"Given many of these people would already have been vulnerable and we have been told this has led to many deaths, I think there needs to be an urgent release of data on the number of deaths that are directly linked to hospital infections.
"Areas with the highest problem are having the highest death toll and if we want to tackle the source issue, this information is vital for public scrutiny of policy."
Hywel Dda UHB saw its hospital-acquired infection rate almost double between November 15 and 22 - from 21 to 42 - while Aneurin Bevan UHB, which opened The Grange University Hospital on November 17, saw the biggest fall over the same period from 71 to 23.
In response to the figures, a Welsh Government spokeswoman said: "Health boards have implemented a range of measures to prevent transmission of Covid-19 in hospitals. These include the testing of patients coming into hospitals for procedures, extensive use of PPE and ensuring Covid and non-Covid patients are separated through the creation of segregated zones and pathways within hospitals.
"As the transmission rate of coronavirus rises, we have seen an increase in Covid-19 infection in some of our hospitals. We work closely with health boards and Public Health Wales to ensure any hospital outbreak is brought swiftly under control."
Meanwhile, new Welsh Government figures show the number of hospital beds occupied by Covid-19 patients is now exceeding levels seen at the peak in April.
As of November 24, 1,692 beds were taken up with confirmed, suspected or recovering cases of the virus, representing 22% of all hospitalisations. This is an increase from 1,653 beds the same day in the previous week.
Some 959 beds were occupied with confirmed Covid-19 patients according to latest figures, a decrease from 1,031 the previous week.
When it came to the most seriously ill patients, 70 invasive ventilated beds were occupied with Covid-19 related patients as of November 24. This is a rise on the 62 beds on the same day in the previous week but is well below the peak in April of 164.