On the face of it, statistics suggest that Wales could be the new hotspot for coronavirus infections. But how reliable are the figures?
The latest data suggests that Wales does have more Covid-19 cases per capita than any other country in the UK.
For every 100,000 people, there were more than 373 positive test results. That compares to 248.5 in neighbouring England.
Looking at local authorities in England and Wales, the five places with the highest rates are all in south Wales: Rhondda Cynon Taf, Merthyr Tydfil, Newport, Cardiff and Swansea.
Other parts of south Wales are also high on the list, such as Blaenau Gwent and the Vale of Glamorgan.
But how much can we read into this? It’s difficult to know for sure – because of gaps in the data published by the UK government.
How much testing?
The big question is how much testing is being done locally. If one area has done twice as many tests as another, you’d expect it to have more positive results. Likewise, some areas may be doing more contact tracing than others – tracking down and testing people who have been in contact with known cases.
This might cause the number of positive test results to be raised above what you would otherwise expect.
So, in order to compare the data fairly, we need to build up as much detail about testing in each area.
In Wales, this data is published for each local authority. For instance, we know that roughly 1.7% of local people have been tested in Rhondda Cynon Taf – compared to just 0.7% in Powys.
However, similar figures are not published in England. We know that 1,593,902 people have been tested across the whole of the UK, as of 14 May, which works out at around 2.4% of the total population. But we can’t break this down by every council area.
Death statistics may paint a more accurate picture of what has happened – because they are not affected by the number of tests being done. However, there is a time-lag with these figures, because there could be several weeks between someone catching the virus and then dying.
In other words, death statistics may not tell us about the current spread of the virus – but they might help us spot previous flare-ups.
Various media reports have emerged since March, saying that south Wales is an infection hotspot. So the question is: was this followed by a spike in the number of coronavirus deaths?
According to figures from the UK Department of Health, there have been 1,154 recorded Covid-19 deaths in Wales since the pandemic began. That compares to 29,637 deaths in England.
When adjusted to population size, this works out at around 36.6 deaths per 100,000 people in Wales. But the proportion is actually higher in England – at 52.7 deaths per 100,000 people.
In other words, concerns over previous flare-ups in Wales do not appear to be reflected in subsequent death statistics. This suggests there could be alternative reasons why positive test results are particularly high in the area.
Public Health Wales agreed that a range of different factors may be influencing the numbers – creating the impression that there is an infection hotspot. Instead, the organisation suggested the high local rates can be partly explained by the way testing has been carried out in the area.
A spokesperson said: “In Wales, we have been testing healthcare workers since 18 March, and other key workers since 6 April. Although it is impossible to say for sure, it is reasonable to assume that the increased identification of cases, and the lower case mortality rate in this analysis, is linked with our approach to testing in Wales.”
The issue has also been addressed by the Welsh First Minister, Mark Drakeford. Speaking in March he said that an apparent surge of infections within the Aneurin Bevan University Health Board (covering a large area of south Wales) could be partly explained “because we’ve tested more people than elsewhere”.
Reports also say that the Aneurin Bevan trust was the first in Wales to start testing its staff for coronavirus.
Mr Drakeford gave another “note of caution” about the statistics on Monday, saying: “[The statistics] rely on testing – and testing regimes are different in different places. So they may not be telling us everything we need to know.”
But he added: “If you are older and sicker and poorer then you are more vulnerable to the disease than you are if you don’t share those characteristics. And Wales has a population that is older and sicker and poorer than the United Kingdom as a whole. So you are seeing some reflection of that in these figures as well.”
Clearly, there is a lot more to these figures than first meets the eye. It is very difficult to make definitive conclusions.
However, based on the death statistics – and the knowledge that testing may have been carried out differently in south Wales – it seems likely that previous claims of a major flare-up in south Wales can be largely accounted for by local differences in testing.
Of course, this does not rule out a real flare-up of cases now or in the future in Wales.
Because full testing data is not published in England, it’s impossible to identify local hotspots across the wider UK in a meaningful way. Instead, we will have to wait several weeks for death statistics that will reflect how the disease is spreading at the moment.