There's a mysterious pattern in the deadliness of COVID-19. Countries across the world, each with their unique healthcare system, combat the pandemic with varying containment and mitigation strategies, leading to drastically different mortality rates. Substantial disparities can be seen by continent.
European countries have the highest infection and death rates, Asian countries remarkably lower ones, and Canada falls in between Asia and the U.S. What really explains these stark differences?
The extent of testing is a possible explanation. Since the outbreak in January 2020, testing for COVID-19 was widely accessible in Asia; Germany, the European country with the lowest mortality rate, also deployed early testing. Although a lack of testing may result in underestimation of cases and deaths, countries that have better control of the outbreak ensured wide access to testing. It does not appear that widespread testing makes the epidemic look worse by finding more people with minor or no symptoms. Infection rates are low in Asian countries and high in the U.S. and Spain where testing was less available.
Another possible explanation is that countries define and report COVID-19-related deaths differently, and those methods changed over time. In the early phases of the epidemic in mainland China, the first few versions of case definition required that up to six criteria needed to be met, which probably underestimated cases by . As of April 14, 2020, the include counting both confirmed and probable cases, which depended on doctors' judgment based on symptoms and contact history. The attribution of cause of death to COVID-19 probably varies by country, especially since most of these deaths occur in people with chronic illnesses.
Demographics also matter. In Hong Kong, were incoming travelers, largely consisting of returning students and expatriates. In , outbreaks in foreign worker dormitories constitute 80% of cases, while community cases only account for 10%. These younger populations are relatively healthy and may contribute to overall lower mortality rates. In contrast, in such as France and Italy, and in the U.S., community outbreaks in nursing homes and long-term care facilities contribute to higher infection and mortality rates among the elderly.
The countries also differed in the capacity of their healthcare systems to handle a rapidly spreading epidemic. When surges of patients overwhelm the healthcare system's capacity, mortality rates skyrocket. The ultimate aim of containment and mitigation strategies is to control infection rate to a level within healthcare systems' capability and avert "hot spots" such as in Wuhan, Italy, and New York.
Needless to say, rapid and robust preparedness and response strategies make a substantial difference. Death rates were much lower in countries and regions that had standing plans for containing the infection. For example, Singapore, Hong Kong, China, and Canada had confronted the Severe Acute Respiratory Syndrome (SARS) epidemic in 2003. That very serious threat had led them to develop national strategies to build capacity, preparedness, coordination, and communication in preparation for the next outbreak. The painful experience of SARS also resulted in a higher level of public acceptance and adherence to masking and social distancing measures.
We do not know for sure why some countries did so much better in confronting the current pandemic. Certainly, there are other factors that might explain the wide variability in death rates. But we do know that countries share the same goals to mitigate the pandemic and should not be islands attempting to confront the crisis independently.
To be sure, we have different cultures, approaches to healthcare, and political systems. But, the observation that infected people in the U.S. are 60 times more likely to die compared to Singapore is too serious to ignore. In light of these striking differences, a more unified approach in deploying testing, reporting cases, and implementing containment measures, whether through the World Health Organization or other entities, is urgently needed to bring struggling countries to better control.
, is a physician from Hong Kong. She is an oncologist in training and a fellow at Clinical Excellence Research Center, Stanford University. , is a distinguished research professor of public health and medicine at UCLA and is currently a faculty member at the Stanford Clinical Excellence Research Center. He is a former associate director of the NIH and former chief science officer of the Agency for Healthcare Research and Quality.