Every day we get a significant figure for deaths in the UK. Everyone jumps on this number, considering it as the last assessment. However, the NHS England figures – which currently account for the bulk of deaths in the UK – actually reflect the day the death was reported, not the actual date of death, which is usually days, sometimes weeks. , before it appears in the numbers.
The truth is that we do not know how many deaths took place the day before. In fact, the overall figure is likely to under-report the number of deaths that occurred the day before.
The number we usually hear from mainly counts deaths that occurred on an earlier date. The difference is important because by underestimating the number of deaths, we bias the curve.
Professor Sheila Bird, formerly of the Biostatistics Unit of the Medical Research Council at the University of Cambridge, explains: “We are on an upward trend in epidemics, and therefore the number of deaths is currently increasing, and we are trying to follow their sharp increase. If today I discover a series of deaths that have occurred in the past 10 days, then what I am receiving is not a reflection of the slope of the curve right now. “
On March 30, the NHS England reported 159 deaths within 24 hours to 5 hours on Sunday March 29. However, the actual number of deaths during this 24-hour period has been revised to 401 in Thursday’s report and to 463 Friday, as more deaths have occurred on that date. And that number could be revised upward as more deaths are discovered.
“When you’re on an upward trajectory, the reporting delay probably means that you underestimate the slope [of the curve] and therefore we can think that we are doing better than us. And when we come to the recession of the epidemic, the slowdown and the decrease in deaths, we will be too slow to recognize the change. As a result, we risk going both ways, ”adds Bird.
Another complicating factor is that the daily count of the Department of Health and Social Services covers deaths in hospitals, omitting those in the community. Although the NSO started this week to publish the number of deaths, including community deaths in England and Wales, there is also a time lag in these data.
There are other data sets that we can examine. The number of confirmed virus cases is a useful indicator, but it is based on tests, which have not been deployed to cover a sufficiently large swath of the general population to give us an idea of the number of people potentially infected.
The number of triage calls and online assessments through the NHS are also helpful in giving us an idea of the potential infection levels – 1.9 m at the time of writing in England. But these are people with symptoms of Covid-19, not those with confirmed cases of the virus.
The most solid data available showing the trajectory of the impact of this virus is deaths. This is why it is imperative that we have reliable and up-to-date data – and why the severity of the problem increases with the death toll.
“It’s not uncommon for this to happen in a new epidemic,” says Bird. “Reporting delays are something to manage, not to be ashamed of. You manage them, but you don’t want to do it by making people believe that they will be blamed for reporting delays and therefore run the risk of not reporting them. This is the worst possibility. “