Be wary of claims Covid-19 deaths “soar” on Tuesdays
10 November 2021
What was claimed
Daily Covid deaths in the UK soared on 9 November 2021.
This is missing key context. The number reported on that day was higher than the day before, but this happens almost every Tuesday, which usually includes the backlog from the weekend. The weekly average number of daily reported Covid-19 deaths actually fell on 9 November 2021.
UK daily Covid deaths hit 262 in highest rise in a WEEK
Several newspapers gave a misleading impression of the latest Covid-19 death figures on Tuesday 9 November 2021.
While it was true that 262 deaths within 28 days of a positive Covid test were reported in the UK that day, this did not represent a rise in the general trend. The average daily number of reported Covid deaths actually fell slightly on 9 November, to about 166.
The number of Covid deaths reported is often very high on Tuesdays, which generally include many deaths not reported over the weekend.
Overall, deaths involving Covid have risen since the summer. On average, there have been more than 100 a day throughout the autumn.
We’ve written before about how daily Covid death figures can be distorted, both upwards and downwards, by reporting delays.
So most deaths announced on Monday were reported on Sunday. Most announced on Sunday were reported on Saturday, and so on.
However, the reporting process is generally slower at the weekend. As a result, the number of Covid-19 deaths announced on Sundays and Mondays is typically low. Then the reporting catches up on Tuesdays, when many of the missing weekend deaths are added to the day’s total, making it higher.
This causes the number of Covid deaths by reporting date to rise and fall in a weekly cycle. It doesn’t mean that there are dramatic changes in the number of people dying each day.
The “About” section on the government’s Coronavirus Dashboard says: “Counts of cases, admissions, deaths, etc vary from day to day just through natural random changes, but also tend to vary throughout the week systematically, so that rates are consistently lower at weekends for example.”
To see how daily deaths are really changing over time, the Coronavirus Dashboard recommends looking at a weekly average. This evens out the fluctuations, because it always includes data from each day of the week.
We also have data showing the number of Covid deaths by date of death, not date of reporting. However, it often takes a few days for a death to be reported, so the totals for the most recent days are usually incomplete.
The dashboard shows the centred average on each day, meaning it includes the figures from the three days before and the three days after. At the time of writing, we don’t yet know the figures for the three days after 9 November, so we’ve calculated a trailing average, which includes the six days before instead.
This trailing average rose in the second half of October, and has been roughly flat in November so far.
However, it is often misleading to say that reported deaths “soared”, “climbed” or “rose” on a Tuesday, as the Evening Standard, The Guardian and Sky News did on 9 November, unless you’re talking about the average.