Research Monitor

January 12th 2021


A Chinese study published in The Lancet, a prestigious medical journal, investigates the long-term health consequences of COVID-19 infection. Even for those who recover from the virus, COVID-19 symptoms can persist for months after infection. This is the so-called “long COVID,” a condition that is still little understood.

To assess the disease’s long-term progression, Dr Chaolin Huang from the Wuhan Research Centre for Communicable Disease Diagnosis and Treatment, Dr Lixue Huang from China’s National Centre for Respiratory Medicine, and a team of their collaborators tracked the post-recovery of 1,733 patients admitted to Jin Yin-tan Hospital (Wuhan, China) with COVID-19, between January and May, 2020.

Between June and September, the academics gave patients an in-person follow-up visit. To evaluate their symptoms and quality of life, they were interviewed using a questionnaire and subjected to a physical examination, laboratory tests and a six-minute walking exercise to gauge their respiratory fitness and lung performance.

The results were stark. Of the patient sample, 76% still experienced at least one COVID-19 symptom six months after their initial infection. The most common symptom to persist appear to be fatigue or muscle weakness, with 63% of patients in the study still reporting discomfort. The next most common symptom was difficulty sleeping, with 26% of patients still reporting issues. This was followed by anxiety and depression, with 23% reporting.

Those who had been severely ill in hospital still frequently experienced impaired lung and respiratory function. This was borne out by a higher prevalence of abnormalities in chest imaging scans. After six months, the levels of COVID-19-specific antibodies in sampled patients had also fallen by 52.5%––a drop of more than half––compared with their peak infection.

Unfortunately, this final result also suggests that any immunity granted by the gamut of COVID-19 vaccines may be relatively short lived––potentially requiring a seasonal booster shot.


A paper published in the American National Bureau of Economic Research (NBER) Working Paper Series estimates the medium to long-term effects of the COVID-19 unemployment shock on life expectancy and mortality rates.

In economics, there is a well-established connection between poverty, unemployment and life-expectancy. The existing research suggests that, in the year after a job displacement which results in an extended period of unemployment, subjects experience an increase in mortality of between 50 and 100%. Even 20 years after displacement, a period of long-term unemployment is still associated in mortality rates 10-15% higher than would otherwise be expected. For someone displaced at the age of 40, this translates into a loss in average life expectancy of between 12 and 18 months.           

To understand the implications of the COVID-19 economic crisis for medium to long-term mortality rates, Francesco Bianchi of Duke University, Giada Bianchi of the Harvard University and Dongho Song of John Hopkins University performed a statistical analysis of previous large-scale unemployment shocks in the United States and their effects on mortality rates over time. This detailed historical information was then used to forecast the possible effects of the ongoing COVID-19 economic crisis on future mortality rates.

The study’s findings make for grim reading. The unemployment shock due to COVID-19 was estimated to be between 2 and 5 times larger than a typical unemployment shock in the United States, contingent on the race and gender make-up of the sample. As a consequence, the academics estimate that the overall American population is likely to see an overall mortality-rate increase of 3% over the next 15 years, as well as a 0.5% drop in average life expectancy––purely as a consequence of COVID-19-related unemployment.

If correct, this would mean 890,000 additional premature deaths over the next 15 years, beyond deaths directly from COVID-19 itself. Over the short-term, this mortality rate shock is expected to be felt disproportionately among women and African Americans, given existing trends. However, over the long-term it is expected to be felt more strongly among white men.


A separate paper also published in the American National Bureau of Economic Research (NBER) Working Paper Series tests the hypothesis that nations with a greater historical exposure to big societal shocks are better prepared to mount societal responses to unrelated shocks in the future.

There is a solid body of evidence indicating that exposure to big societal shocks changes people’s long-term behaviour. For example, there is strong evidence from a wide range of countries suggesting that exposure to the violence of war increases individuals’ general social participation in the war’s aftermath. There is some evidence that it also makes individuals more likely to make decisions for the benefit of others.

To test the extent to which prior exposure to big shocks has primed a country’s response to the COVID-19 pandemic, Michael Lokshin and Vladimir Kolchin of the World Bank, along with Martin Ravallion of Georgetown University investigated whether there was a relationship between a country’s loss of life in the COVID-19 pandemic to date and its loss of life in the largest shock of the 20th century––namely, World War II. To make this comparison, the authors utilised two sets of cross-country data on mortality rates, focusing on Europe, Russia and Central Asia. The academics then tested the robustness of their results with an extended set of countries with global coverage.

The fact that different countries’ responses to the pandemic––and the pandemic’s course in those countries––have been markedly diverse, even among close cultural and geographic neighbours, has now become almost a cliché. As a consequence, the strength of the study’s results may come as a surprise. The comparison between the cumulative number of deaths suffered in World War II as a proportion of a country’s population, and a country’s cumulative mortality rate per million people during the COVID-19 pandemic, indicates a strong negative correlation between the two.

The two countries at either pole of this spectrum are Belarus and Belgium. Over 25% of Belarus’s population was lost in World War II, but its cumulative COVID-19 mortality rate is below 100 per million inhabitants––one of Europe’s lowest. The opposite is true of Belgium, which lost less than 2% of its population, but has a cumulative COVID-19 mortality rate of over 800 people per million inhabitants––one of Europe’s highest.

The study suggests that big societal shocks have surprisingly persistent effects on a country’s ability to adapt and respond to future shocks. Given that the COVID-19 pandemic is unlikely to be the last major shock of the 21st century, let us hope that this proves correct.

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