The Office for National Statistics (ONS) have released provisional counts of the number of deaths registered in England and Wales in the week ending 2 April 2021.
Prof Paul Hunter, Professor in Medicine, The Norwich School of Medicine, University of East Anglia, said:
“It’s difficult to interpret this week’s death stats as the final week included Good Friday so will be an under-estimate. So it probably looks better than reality because of one day’s data being missing till the following week.”
Prof Kevin McConway, Emeritus Professor of Applied Statistics, The Open University, said:
“ONS have published their regular bulletin of provisional data on death registrations in England and Wales. It takes the data up to the week ending 2 April, and that already draws attention to a big problem in interpreting the trends. Friday 2 April was Good Friday this year, a bank holiday, so that some death registrations that might have occurred on that day did not take place then. So numbers of deaths registered in the most recent week will be lower than they would have been without the holiday. This is arguably the worst time of year for disruption to short-term trends in death registrations. Not only are there two bank holidays (Easter Monday as well as Good Friday), but comparisons with average numbers of deaths in corresponding weeks in previous years are complicated by the fact that the date of Easter changes from year to year, so that the Easter bank holidays fall into different weeks in different years. ONS are very clear about this issue in their bulletin, but it does mean that short-term trends, such as changes between the most recent week and the week before, can be misleading. Therefore I won’t go into as much detail about them as I sometimes do – but some comparisons do still make sense, as I’ll explain.
“One way round these calendar difficulties is to use data classified by the date when the deaths actually occurred, rather than the date when they were registered. ONS do publish data by occurrence date as well as by registration date, but that doesn’t deal with the issue of looking at short-term trends. That’s because deaths are not registered immediately after they occur – there’s usually a delay. The median time between the occurrence and registration of a death in England and Wales in 2019 was four days – that is, half of death were registered within four days, but the other half were not, and some of them took very much longer to register. (In 2019, 11% of deaths were still not registered two weeks after then person died, and half of those were still not registered three months after the death.) Delays are likely to be rather longer around bank holidays. So counts of deaths by date of occurrence around bank holidays will be incomplete for the most recent week for which data are published, and will be revised upwards later as the later registrations come in. Indeed revisions like that happen for all weeks, not just the most recent, though they are usually biggest for the most recent.
“Having got this complication out of the way, what do the data show? Good news, though we’ve got to be careful with the interpretation. Total death registrations from all causes were 18% down, for the most recent week compared to the week before that, but a considerable proportion of that fall will be because of the bank holiday issue. The number of deaths registered that week is almost 2,000 below the average of the previous five years, but the Good Friday bank holiday occurred in the corresponding week in only one of those five years and was in a later week in the other four, so the comparison is not all that helpful. Total death registrations were below the five-year average, mostly considerably so, in England considered separately, in Wales, and in every English region, but the same proviso about the bank holiday applies. There were only 400 deaths registered in England and Wales in the latest week where Covid-19 was mentioned on the death certificate – that’s 44% down on the previous week, but the same bank holiday issue does arise. For most of those 400 deaths, in fact 308 of them, Covid-19 was coded as the underlying cause of death.
“There are some comparisons that can be made that are less affected by the bank holiday issue. In the most recent week, registered deaths involving Covid-19 made up just 4.9% of all deaths registered in England and Wales. The previous week, deaths involving Covid-19 made up 7.2% of all registered deaths. Assuming that the bank holiday delayed registrations for Covid-19 related deaths and other deaths at roughly the same level, that’s a very clear decrease in the impact of Covid-19 on deaths. Back at the height of the latest wave in mid-January, over 45% of all registered deaths involved Covid-19. The last time deaths related to Covid-19 made up as few as 5% of all deaths was in mid-October last year. There’s still some way to go before we get to the level between mid-July and mid-September last year, when only one or two per cent of registered deaths involved Covid-19. So I’m not complacent and we must still be careful, now that restrictions on what we can do are being lifted. But the news so far is good.
“Other comparisons that won’t be much affected by the bank holiday issue are comparisons between age groups. In people aged 50 and over, the number of registered deaths involving Covid-19 was 46% lower in the most recent week than in the week before. That comparison will have been affected by the bank holiday, and the true fall will be less than that, though I think, still very substantial. However, the number of deaths involving Covid-19 in people aged under 50 increased very slightly between those two weeks, from 26 to 27 deaths. The fact that it did increase isn’t at all concerning, because the numbers are so small and will therefore be affected a lot by random statistical variation from one week to another. But what these numbers for different ages do point to is the effect of vaccination in reducing deaths in older people. There’s nothing in the death registration data that prove for certain that the differences in trends between older and younger people are caused by the vaccination, but vaccination must surely be playing a very major role. In reductions in the counts of Covid-19 deaths, vaccination of younger people won’t have so much of an impact, because there are far fewer deaths in those younger groups anyway – but vaccination also reduces the risk of serious illness at all ages, and is likely to help in stopping younger people passing on infection to older people.”
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Prof Kevin McConway: “I am a Trustee of the SMC and a member of its Advisory Committee. I am also a member of the Public Data Advisory Group, which provides expert advice to the Cabinet Office on aspects of public understanding of data during the pandemic. My quote above is in my capacity as an independent professional statistician.”
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