Covid 19 facts and uncertainties

In thinking about the people who’ve died as a result of Covid 19, we remember that they are real people, whose lives were cut short, leaving behind grieving families, friends and colleagues as well as the NHS staff, carers and funeral staff who did their best at great cost to themselves and their families. And for everyone who has died many others will have survived but been greatly harmed.

This blog post looks at data about the Covid-19 deaths in England, in order to try and be clear about what the different data sets are. And in so doing, to help us work through the many uncertainties about how best to respond to the pandemic, so that transmission is eliminated in accord with a zero Covid strategy.

What we the public think and do is crucial – it is because of our actions that Covid 19 has been brought under control to the extent that it has.

Based on his analysis of Office of National Statistics data about Covid19 deaths as of May 23rd 2020, social geographer Danny Dorling concluded,

“This disease was brought under control despite the actions of central government, not because of them…”

This conclusion is based on data that show that mortality rates fell at the start of April when the number of infections fell at the start of March, because people (weeks before central government began to express any sense of urgency) began to change their own behaviour.

Handling uncertainty when urgent action is vital

We are not out of the Covid19 woods. The government is quickly re-opening different sectors of the economy, without waiting to check on the effects and see if one is safe before lifting others.

Evidence from other countries is that some sectors are particularly risky and their reopening has been followed by new spikes of Covid-19 infections.

Source: IndieSAGE – https://www.ecdc.europa.eu/en/publications-data/download-todays-data-geographic-distribution-covid-19-cases-worldwide
Source: IndieSAGE – https://www.ecdc.europa.eu/en/publications-data/download-todays-data-geographic-distribution-covid-19-cases-worldwide

The latest data (updated on Friday 24 July 2020 at 4:28pm) on the UK government’s website https://coronavirus-staging.data.gov.uk/ shows a rise in the number of new UK confirmed Covid-19 cases.

The July 22nd British Medical Journal article Managing uncertainty in the covid-19 era points out,

“uncertainties continue to multiply both for individuals and policy makers. Should I return to work? Should I visit relatives? Which businesses should re-open? What about schools and universities?”

It adds, 

“The stage of the current pandemic requires us to work with imperfect data…In this context, purist pursuit of an illusory one-dimensional truth is doomed to failure. Instead, we must generate and collaborate to achieve ‘viable clumsy solutions’. By carefully evaluating how these imperfect responses unfold in messy real-world settings, we can help to build the multifaceted evidence base that the world urgently needs.’

Here’s an attempt to at least be clear about what some of the imperfect data are.

There are four different sets of data about deaths caused by Covid 19:

Total number of deaths in English hospitals of people who’ve tested positive for Covid19: 29,146 people up to 4pm on 15 July (Source here)

Total number of deaths in England of people whose death certificates mention confirmed or suspected Covid 19, wherever the person died: 50,946 people up to 10 July (Source: Office of National Statistics: Deaths registered weekly in England and Wales, provisional, release date 21 July 2020)

Death certification as involving COVID-19 does not depend on a positive test. The Office of National Statistics have published a summary of where you can find data on COVID-19 infection rates and deaths for England, Wales, Scotland and Northern Ireland.

Total number of deaths registered in England of people who tested positive for Covid 19: 45,677 as of 16 July (Source: https://coronavirus.data.gov.uk/ )

This data is reported by Public Health England. It is based on deaths of people who had tested positive in Pillar 1 tests (hospital patients and staff) and Pillar 2 tests (the commercial tests carried out in the community).

On July 16th the Oxford Uni Centre for Evidence Based Medicine published an article pointing out that these figures include deaths of people more than 28 days after testing positive for Covid19. The other UK countries only include deaths of people who tested positive from Covid19 up to 28 days after their test.

On July 17th, the government paused reporting data about the deaths of people who had tested positive in Pillar 1 and Pillar 2 tests, while they investigate.

Source: https://www.gov.uk/guidance/coronavirus-covid-19-information-for-the-public

However, this is very confusing because as of 24 July 2020 the data reported by Public Health England includes the numbers of Covid-19 deaths for each day from 17 July-24 July. This table shows 123 people died of Covid 19 on 24 July, all of them in England.

Source: https://coronavirus-staging.data.gov.uk/deaths, accessed 24.7.2020, 23.27

Total number of “excess” non-Covid19 deaths in England and Wales since the start of the Covid 19 pandemic to 1 May (the most recent Office of National Statistics data): an excess of 46,380 death registrations compared to the five-year average; 12,900 of these deaths (27.8%) did not involve the coronavirus (COVID-19).

The Office of National Statistics explains:

  • Non-COVID-19 excess deaths occur predominantly in older age groups, to a greater extent with increasing age, and especially for the frail elderly with underlying conditions; undiagnosed COVID-19 could help explain the rise in these deaths.
  • In the period from Week 11 (ending 13 March) to Week 18 (ending 1 May), over 8,000 fewer deaths were registered in hospitals than in the corresponding period in the weekly average, a decrease of 20.9%; in contrast, almost 11,000 more deaths were registered in care homes, an increase of 60.5%, and over 8,000 more deaths were registered in private homes in this period, an increase of 42.6%.
  • The largest increases in non-COVID-19 deaths compared to the five-year average are seen in deaths due to “dementia and Alzheimer disease” and “symptoms, signs and ill-defined conditions” (the latter mostly indicating old age and frailty); overall, there have been 5,404 excess deaths (an increase of 52.2% on the five-year average) due to dementia and Alzheimer disease and 1,567 excess deaths (an increase of 77.8%) due to “symptoms signs and ill-defined conditions” from Week 11 (ending 13 March) to Week 18 (ending 1 May), which together comprise two thirds of total non-COVID-19 excess deaths in this period.
  • Deaths due to causes such as asthma and diabetes increased up to the week ending 24 April 2020 and occurred increasingly outside hospital; this could suggest a delay in care for these conditions is leading to an increase in deaths, although this rise could also be related to undiagnosed COVID-19.
  • Changes to registration processes implemented in the Coronavirus Act 2020 have led to an increased number of death registrations made by doctors, increasing registration efficiency overall; at present, it is not clear whether increased efficiency is a cause or result of an increase in weekly registrations, but some further effects may become apparent in the future for conditions where deaths have a longer registration delay.
  • There is not enough evidence to suggest the other theories investigated can explain much of the increase in non-COVID-19 death registrations; these other explanations were reduced hospital capacity and increases in deaths caused by stress-related conditions.
  • A full analysis of non-COVID-19 excess deaths will only be possible in several months’ time when longer-term effects and additional data, both death registrations and other sources, can be considered.

The death rate in confirmed cases is not the overall Covid 19 death rate and we don’t know what that might be

We lack accurate data on the overall death rate (aka infection fatality rate) as we don’t know the total number of people infected (and may never know).

The overall death rate is important because many people want to know if someone is infected with COVID-19, how likely is it that they will die?

In March 2020 the World Health Organisation suggested that the overall death rate for the population following infection could be around 3%.

(Although this figure might now be out of date, it’s obviously far less than UK rate of death based on confirmed cases so far – aka the case fatality rate. This was 14.13 with a 95% confidence interval as of 26th May. For all kinds of reasons, the case fatality rate varies over time and between places)

We just don’t know how many people would die if there is another wave of Covid 19. So the Academy of Medical Sciences Report urges caution, warning that,

“The UK must prepare now for a potential new wave of coronavirus infections this winter that could be more serious than the first.”

It stresses that preparations must include,

“Minimising transmission of coronavirus in the community, with a public information campaign for all, as well as advice tailored to individuals and communities at high risk.”

And that’s another consideration: that the risk of catching and dying from Covid 19 is not evenly spread across the population. It disproportionately afflicts not just the already poorly and the elderly, but key workers, black and asian people and people living on low incomes and in areas of poor quality overcrowded housing.

Update 25 July 2020: The Office of National Statistics reports:

In England, the age-standardised mortality rate for deaths involving COVID-19 in the most deprived areas between March and June 2020 was 139.6 deaths per 100,000 people; this was more than double the mortality rate in the least deprived areas (63.4 deaths per 100,000 people).

We’re probably heading in a direction where countries converge towards a single global death rate.

In a 27th April blog post, Danny Dorling notes a wide variation in different countries’ coronavirus fatality rates based on confirmed cases. At the lowest, Singapore had a 0.1% case fatality rate. The highest was 14.6%, in Belgium.

He points out that this disparity is due to different testing strategies in different countries:

“In Belgium, it is almost exclusively people who are very ill who are tested and so the mortality rate appears to be 150 times high than in Singapore where a much wider range of the public has been tested.

But the real mortality rate of these two countries will end up being very similar, and much nearer to the lower end of the range. It is extremely unlikely that Singapore, with its very efficient health system, is failing to record the deaths of those known to have the disease.”

He continues,

“Over time, all of these mortality rates will probably begin to converge on a single global rate of those who have caught the disease. This is what has happened in the past. The flu of 1918 may have had a mortality rate as high as 2% of all those who caught it. In contrast, the H1N1 flu of 2009 had a mortality rate 100 times lower at 0.02%.

For COVID-19, the final rate will tend to be towards the lower end of the spectrum shown, if this disease is at all like previous pandemics, which we don’t know for sure yet.”

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