Changes to government Covid-19 death data won’t make a big difference to the overall death count

On 16 July, the Centre for Evidence Based Medicine published an article which warned that, under Public Health England’s (PHE) system of reporting deaths from coronavirus, a patient who tested positive for Covid-19 but was successfully treated in and discharged from hospital would still be counted as Covid-19 death “even if they had a heart attack or were run over by a bus three months later.”

It described this as a “statistical flaw that leads to an over-exaggeration of Covid-associated deaths.”

This prompted Matt Hancock, the health and social care secretary, to demand an urgent review of PHE’s data. The announcement of daily death data has been paused while the review is carried out (although the data itself is still published online). Our readers have asked us about how much of a difference this makes to the total death toll.

PHE has suggested that changing the way it counts deaths is unlikely to make a big difference to the overall death toll. In a series of tweets, it said that around 90% of the 40,528 Covid-19 deaths reported by 15 July 2020 had occurred within 28 days of a positive test. Of those who died after 28 days, Covid-19 was stated as the main cause of death on the registration form for 47%. 

This suggests that approximately 5% of those deaths were people who died more than 28 days after receiving a positive test and did not have Covid-19 as the main cause of death (which would put the figure at around 2,000). 

PHE also noted that if it was to only count deaths of those who died within 28 days of a positive Covid-19 test, then 4,149 deaths of people with a laboratory confirmed infection would have been excluded from that 15 July death count.

Dr Susan Hopkins, PHE’s incident director, said the decision to count all those who have died who had a positive Covid-19 test at any point was to “ensure our data is as complete as possible”.

“We must remember that this is a new and emerging infection and there is increasing evidence of long term health problems for some of those affected. Whilst this knowledge is growing, now is the right time to review how deaths are calculated.”

It’s important to say that while the PHE figures appear to slightly overestimate the number of people who tested positive for Covid-19 and died from it, they likely underestimate the true number of people who have died from Covid-19.

That’s because they don’t capture cases where someone has died of Covid-19 but this has not been tested for. 

The Office for National Statistics (ONS) publishes data on the number of deaths involving suspected or confirmed Covid-19 according to the causes of death listed on death certificates.

This shows that as of 10 July 2020, 48,388 deaths involving suspected or confirmed Covid-19 had been registered in England, while PHE figures at that time showed 40,213 people had died after a Covid-19 positive test in England.  

Also, the number of excess deaths (the number of deaths in excess of what might be expected in a normal year) during the pandemic has been higher than either PHE’s or the ONS’s figures on Covid-19 deaths.

This could suggest that there are even more deaths involving Covid-19 that neither PHE nor the ONS are picking up, but this is still uncertain.