May 12, 2020

expert reaction to study estimating excess deaths over one year directly or indirectly related to COVID-19 based on underlying health conditions and age of UK population, and making comments on the effect of easing the lockdown

A study, published in the Lancet, reports estimates excess deaths over one year directly or indirectly related to COVID-19 based on underlying health conditions and age of UK population, and making comments on the effect of easing the lockdown.

Prof Mark Woolhouse, Professor of Infectious Disease Epidemiology, University of Edinburgh, said:

“This study by Banerjee and colleagues is timely because it underlines the importance of two pillars of the UK government’s COVID-19 response published earlier this week.  However, the study is not a direct examination of the effects of easing the lockdown.

“Commenting on the paper:

“We now understand that the risks of severe disease and death are far from equally distributed across the population; they are concentrated in an identified minority of individuals.

“There is a relatively small group – around 2% – who have co-morbidities or underlying health conditions and have been advised to “shield” themselves from infection.

“There is a much larger group – everyone over 70 years old, almost 20% – who have been advised to carry out “enhanced” social distancing.

“This paper illustrates why shielding and enhanced social distancing are so important.

“The authors have conducted an inventory of who in the UK is at greatest risk of dying from COVID-19.  They go on to explore how epidemics of different scales would affect excess mortality over the coming year.

“The study is based on existing knowledge of risk factors for death from COVID-19.  These include a wide range of co-morbidities and, importantly, age; people over 70 are at greatly increased risk.  Many people have multiple risk factors.

“The study considers a wide range of epidemic sizes and a range of levels of increased risk, and for each set of assumptions calculates excess mortality.  They estimate a worst case of 73,000 excess deaths within one year from the direct and indirect effects of the COVID-19 pandemic; but it is important to stress that this is a worst case – the actual number of excess deaths may well turn out to be considerably lower.  And once again it is important to stress the study did not look at the specifics of the lockdown or of easing the lockdown, so these numbers do not apply to that.

“Estimates of this kind are a useful public health tool and will be refined as our understanding of the risk of death following COVID-19 infection improves.”

Prof Rowland Kao, Sir Timothy O’Shea Professor of Veterinary Epidemiology and Data Science, University of Edinburgh, said:

“This study performs a very useful function in putting the impact of COVID-19 in the context of other conditions and co-morbidities.  The extrapolation to determining excess deaths due to COVID-19 related causes helps to illustrate the enormous difference that could result from different degrees of success at controlling the pandemic in the UK, and highlighting the uncertainties in what we don’t know.  In particular, our current uncertainty in the relative risk or mortality associated with COVID-19, introduces approximately a 10x variation in the expected excess deaths over a single control scenario.

“An important caveat to interpreting these figures is in understanding the role of deprivation.  It is now well known that deprivation plays a critical role in determining the impact of COVID-19 on the population.  In part this study considers deprivation related factors, due to relationships between deprivation and health.  However, what is unclear is the role that deprivation plays in transmission of the virus; for example due to higher levels of contact in low income housing, or imperfect distancing that may occur in many lower paid jobs.  Understanding those impacts will be a critical factor in understanding how relative risks impact different sectors of society, impacts that would be better understood with analyses that also consider questions of long term immunity, community structure and transmission that are beyond the scope of this study.

“It is important to note this study did not model the easing of the lockdown – so it cannot make conclusions about that.”

Prof Sarah Harper, Clore Professor of Gerontology, University of Oxford, said:

“This is an important paper which shows the complexity of mortality risk factors and how age, sex and underlying health conditions combine under different conditions to increase risk.

“From a policy perspective, for example, the paper rightly states that it shows how policy might consider age in combination with underlying conditions.  For example, a man aged 66–70 years with no underlying conditions, is not currently considered high risk.  Yet he has a higher background 1-year mortality (1·07%) than that of a woman aged 56–60 years with one underlying condition (0·91%), who is considered high-risk.  Similarly, it shows that generally women’s mortality risk at any given age is the same as men’s who are around 5 years younger.

“The blanket and arbitrary use of age – for example age 70 as a rough cut off for the high risk mortality-category – has been questioned by many already.  This paper highlights the difference between men and women, and the importance of identifying underlying health conditions.  Importantly, the authors suggest that this enables a publicly available tool for individuals to use to develop better understanding of who is at risk based on reliable health data.  The association between population risk and individual risk is complex, but a transparent public health approach enabling people to understand the evidence behind government messages would be welcomed by many.”

‘Estimating excess 1-year mortality associated with the COVID-19 pandemic according to underlying conditions and age: a population-based cohort study’ by Amitava Banerjee et al. was published in the Lancet at 23:30 UK time on Tuesday 12 May 2020.

DOI: 10.1016/S0140-6736(20)30854-0

Declared interests

Prof Sarah Harper: “Sarah Harper is Clore Professor of Gerontology at the University of Oxford.  She writes in this capacity.  She is also a Board member of HDR UK who provided funding for this study.”

None others received.