How do you count the cost of a pandemic? COVID-19 has killed an estimated 15 million people since it emerged at the end of 2019, but its impact on health reaches much further. For hundreds of millions of people around the world, infection with the coronavirus SARS-CoV-2 has brought a range of problems, from the acute effects of the illness to the lasting symptoms known as long COVID.
Working out the size of that health burden is challenging, but important — governments use such figures to plan how to spend health-care budgets. So researchers are starting to tally the overall health impacts and trying to draw lessons from any patterns. They’re hoping, for example, to discern how different populations are affected and to provide evidence about the effects of vaccine roll-outs and new variants of the virus.
Even without a pandemic, there is no easy way to tally all the effects of various health conditions: good data can be hard to come by and decisions on how to measure burdens are inherently subjective. “There are a whole lot of social value choices where there isn’t hard science,” says Theo Vos, an epidemiologist at the Institute for Health Metrics and Evaluation at the University of Washington in Seattle, a research centre that aims to categorize the global health burden of diseases. “How do you value a year with asthma, a year without a leg, a year with depression?”
Those calculations are even harder when scientists are grappling with a new virus and a poorly characterized disease.
Research groups are exploring a number of ways to calculate the burden of COVID-19, and many are starting to report their results. Early data suggest that the impact is significant and varies by country. One study found that COVID-19 took a heavy toll across 16 European countries, but that the impacts on different nations varied owing to factors ranging from the population’s age structure to political responses to the pandemic1 (see ‘A heavy burden’).
Estimates produced by national teams provide more detail. In Scotland2, COVID-19 was second only to ischaemic heart disease in terms of the impact it had on the population’s health in 2020. In the Netherlands3 that year, the burden was 16 times that of a typical influenza season, according to a preprint published last November.Individual-country analyses also reveal big differences in the health burden of COVID-19. Research from Malta reveals that between March 2020 and March 2021, COVID-19 became the fourth leading cause of disability, ranking after ischaemic heart disease, lower back pain and diabetes5. In India, it ranked much further down the list: using 2019 data as a guide, it would have accounted for 3% of the total health burden — putting it outside the top 10 and rating it as less of a burden than ischaemic heart disease, nutritional deficiencies and chronic respiratory diseases6. The authors acknowledge, however, that COVID-19 cases might be under-reported in India, which would affect the rate of DALYs.
Each project sources its data slightly differently, which can add to the variation in DALY estimations. The research group that estimated DALYs for 16 European countries, for example, used aggregated data from the European Centre for Disease Prevention and Control (ECDC), the World Health Organization (WHO) and the World Bank Group; many of the national studies used more-detailed country-specific data. As a consequence, DALY estimates for the same country vary in different hands. Using ECDC, WHO and World Bank data for Denmark, for example, gives a figure of 116 DALYs per 100,000 people1, whereas Monteiro Pires’ group used data from Denmark’s health systems to come up with a figure closer to 520
Several of the studies of individual European countries have been supported by the European Burden of Disease Network, a project launched in 2019 to improve how the burden of disease is calculated and understood. The network of epidemiologists and public-health researchers from 53 countries worldwide quickly realized that it should be documenting the public-health burden of the nascent pandemic virus, and began to develop a consensus protocol, including a specific model for the disease progression of COVID-19 from infection to recovery or death. “From that moment on, many countries have been using that protocol. We never imagined it would happen so quickly,” says Monteiro Pires, who heads the network’s infectious-disease working group. Network researchers have now completed burden estimates for Malta, Denmark, the Netherlands, Scotland, Ireland and Germany, with more expected to appear in the months ahead.
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