January has seen the UK repeatedly set, and break, records for the daily number of Covid-19 deaths being added to the horrific total.
Amid the second wave of the pandemic, these escalating totals have been echoed by the media and widely shared as grim markers of the extent to which the virus has ravaged the nation.
But while it’s important to pay attention to these daily totals, they don’t tell us the whole story.
How the data works
The government presents daily deaths in two ways on its dashboard.
The first is deaths within 28 days of a positive Covid test organised by date of death.
The second is deaths within 28 days of a positive Covid test organised by date of report.
The latter is the number that gets amplified by the media each day, and is not a reflection of how many people actually have died in the previous 24 hours, which is information that takes longer to establish.
Confused? Don’t worry.
Let’s use a completely different example. Imagine if we learned today that 500 people had died during the Blitz whose deaths had never previously been discovered or recorded.
That would mean 500 new deaths had been reported today from the Blitz, but clearly those deaths would not have actually happened today.
In the same way, while 1,000 deaths could be newly reported today, those deaths could have actually taken place on any day of the pandemic, but only now been discovered (or, at least, reported centrally).
The most recent record for a daily report was set on Wednesday, which saw 1,820 deaths recorded in a single 24-hour period.
But if we’re looking at what the actual deadliest day of the pandemic is, we need to know when those people died, which this figure alone doesn’t tell us.
So when did the most people actually die?
A new record for the highest number of Covid-19 deaths by date of actual death was also identified on Wednesday as records updated.
January 12, 2021, is now the deadliest day of the pandemic so far, with 1,136 confirmed deaths on this date. This total, as records update over the coming days and weeks, is likely to increase.
The previous record of 1,073, which had held for months, occurred during the first wave of the pandemic on April 8. One of the deaths on April 8 was reported as recently as this week.
April 8 has also now been surpassed by seven more days. These are the 20 deadliest days of the pandemic so far according to the most recent data, though these totals – especially the later ones – are likely to change as records update.
January 12, 2021 – 1,136
January 13, 2021 – 1,123
January 16, 2021 – 1,119
January 14, 2021 – 1,117
January 11, 2021 – 1,108
January 18, 2021 – 1,102
January 17, 2021 – 1,074
April 8, 2020 – 1,073
January 15, 2021 – 1,053
January 10, 2021 – 1,048
January 19, 2021 – 1,038
April 7, 2020 – 999
April 9, 2020 – 999
January 9, 2021 – 987
January 7, 2021 – 976
April 12, 2020 – 957
April 11, 2020 – 956
January 8, 2021 – 948
April 10, 2020 – 941
April 5, 2020 – 915
As you can see, nine of the top 10 have taken place in January, which seems likely to overtake April as the deadliest month so far.
Why don’t we report on these figures instead?
The main reason the daily increase – that is, deaths by date of report rather than by date of death – makes headlines is that it comes reliably and regularly. Every day from 4pm, the government’s dashboard is updated.
By contrast, the information about fatalities by date of death doesn’t come to light immediately.
A death on, for example, December 20 might take days to verify and report – say, if there is confusion over test results, or a delay in submitting data from a particular health trust, or simply because it has to work its way through a number of databases before reaching the government.
So that person’s death wouldn’t make it into the December 21 data.
How common is this? Well, in reality, the majority of deaths aren’t reported the next day, meaning this method of reporting would be extremely inaccurate if we did it in real-time.
Just 140 of the 765 hospital deaths reported in England on April 9 had actually taken place on April 8. One of the deaths in that dataset had occurred as far back as March 16. April 8 was, until Wednesday, the single day with the highest number of UK deaths: as the months passed, more and more fatalities on that day were reported, bringing the total for England’s hospital deaths alone to 974. That means most of those 974 deaths were reported on subsequent days.
So reporting daily increases by the other method isn’t perfect, but it’s the best data available on the day. We just need to remember what it shows us, and what it doesn’t.
This article originally appeared on HuffPost UK and has been updated.