There was a large rise in reported deaths today among hospital patients who have tested positive for the coronavirus.

The Department of Health and Social Care reported more than 380 more deaths across the UK today, compared to a rise of 180 yesterday.

But experts have long warned not to put too much weight on deaths reported on a single day.

Time lag

While the UK government is putting out a daily number based on people dying in hospital, that doesn’t mean all those people died in that 24-hour period.

There’s a time lag between someone dying and the death being reported. Doctors need to fill in death certificates, family members need to be contacted, and post-mortem examinations are sometimes done.

That means that some deaths from a few days ago are only being reported now. The latest figure does not mean that 200 more deaths took place on one day than on the previous day.

This is why experts consistently warn people not to celebrate if the number is low one day or panic when it is high the next. The important thing is the trend over time.

The statistician Professor Sir David Spiegelhalter from Cambridge University said: “The extreme day-to-day variation in reported Covid-19 deaths is far more than we would expect from chance variability and must be due to reporting practices.

“Some deaths occurred many days ago, and there seems to be fewer reported over the weekend. So great caution is required in interpreting daily figures.

“Over the last week, reported deaths rose on average by an estimated 21 per cent each day, similar to Italy at the same stage of the epidemic, around two weeks ago.

“Italy’s death rate appears to have now levelled off at around 900 a day, and we can hope that our death rate will also flatten off due to the measures started a few weeks ago. It is a good sign that the number of new cases per day is now stable. But this will be a very tough time.”

New data

As FactCheck reported yesterday, the independent ONS is also now publishing new data on registered deaths in England and Wales where Covid-19 is mentioned by a doctor on the death certificate.

Importantly, this new weekly figure also includes people dying outside hospital – in care homes, for example.

It may also include people who have not tested positive for the coronavirus. This might sound strange, but doctors outside hospitals who do not have access to testing kits are able to record suspected cases of Covid-19 on death certificates without having their diagnosis confirmed by a test.

The ONS data inevitably captures more deaths. We learned today that ONS is aware of 210 deaths involving Covid-19 occurring before 20 March, 40 more than the 170 announced by @DHSC by that date.

But there is an even longer time lag between someone dying and the death showing up in the ONS statistics, so the number will always be behind the daily death toll figures published by the UK government.

The daily deaths in hospitals and the weekly figures from registered deaths both carry the same warning: Covid-19 may not always be the main cause of death.

FactCheck verdict

You’ve probably seen the number of coronavirus deaths in the UK reported every day.

Some of the deaths being reported now might have happened days earlier, so experts say we shouldn’t overreact if the number is particularly low or high on a given day: it’s the overall trend that matters.

The daily death toll only covers people who have died in hospital. They have tested positive for Covid-19 but it’s not necessarily the cause of death.

We also now have a weekly figure that takes in people who have died in the community too. But the time lag between death and reporting is even longer here, and we may not even be able to say for sure whether the patient had coronavirus, let alone that it was the cause of death.