Measuring the impact of Covid-19: Why mortality alone is not enough

In an editorial published in the British Medical Journal, we discuss why we must look beyond mortality to the wider burden of pandemic related harms. Over the course of the covid-19 pandemic, daily releases of national statistics on cases and deaths have been widely reported and used to support interventions and judge the success or failure of control measures around the world. However, differences in rates of testing and in reporting of deaths have led to uncertainty about whether national headline figures on deaths are directly comparable. Excess mortality is an alternative metric, which gives a measure of the number of deaths above that expected during a given time period and thus accounts for additional deaths from any cause during the pandemic, irrespective of how covid-19 deaths are defined.

Measuring excess mortality alone offers only partial insights into the impact of the covid-19 pandemic on the health of nations. If we are to truly understand and intervene to mitigate the impact of the pandemic, we must also look to quantify excess morbidity within and between nations. A focus on deaths alone gives only a partial picture of the impact of covid-19 on populations, particularly among younger people in whom death from covid-19 is rare. The importance of “long covid,” for example, has recently been highlighted, but the true burden of this condition has yet to be quantified, and policies are urgently needed to overcome its long term challenges.

The covid-19 pandemic has resulted in widespread disruption to health systems across the world. Diagnostic and treatment pathways for cancer and other time sensitive conditions have been disrupted, and the monitoring of long term conditions has often taken place through novel telemedicine platforms, if at all. By April 2021 more than 4.7 million people in England were waiting for hospital treatment, the highest number since records began. Such disruption is likely to lead to poorer health and earlier deaths in countries across the world for many years to come, particularly where covid-19 remains endemic and where health services are unable to function normally. Establishing where health systems have fallen behind, and characterising the true extent of unmet need, is a critical step towards reducing these ongoing harms.

There has been a huge toll of the covid-19 pandemic on mortality in high income countries in 2020. However, its full impact may not be apparent for many years, particularly in lower income countries where factors such as poverty, lack of vaccines, weak health systems, and high population density place people at increased risk from covid-19 and related harm. In the UK, life expectancy in lower socioeconomic groups has fallen in recent years, an inequality likely to be exacerbated by the covid-19 pandemic, without concerted action.

Finally, although mortality is a useful metric, policy informed by deaths alone overlooks what may become a huge burden of long term morbidity resulting from covid-19. An urgent need exists to measure this excess morbidity, support people with long term complications of covid-19, and fund health systems globally to tackle the backlog of work resulting from the pandemic.


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