For epidemiologists studying the coronavirus today, that scale is still measured by the mundane act of counting. The tally begins with descriptive statistics on the daily state of the pandemic – who is infected, who is sick, how many have died. And then those numbers are used to predict the future of the pandemic, allowing officials to plan and mobilize resources. Epidemiologists use this data to discern trends over time and among different groups of people, and to determine why some get sick and others don’t. This is the difficult part of epidemiology.
We know that the SARS-CoV-2 virus is the cause of Covid-19, and in that sense the story is very simple. But why is one exposed person infected and another not? Despite more than 200 million cases detected worldwide, scientists still don’t understand much about transmission, or what makes an infected person sick enough to be hospitalized, beyond simple demographics like age. and sex.
Almost half a million scientific papers have now been published on Covid-19, and they are assembling a dizzying array of hypotheses to explain the observed patterns, but a large majority of that conjecture quickly crumbles. Many studies noted early on the relative absence of Covid-19 cases in Africa and South Asia, for example, leading to much environmental, genetic and behavioral guesswork, until suddenly African countries and l India are also devastated by the increase in the number of cases. So, so many epidemiological theories came and went, such as the impacts of altitude and blood group. But a constant association has remained, and it is the same one that Dr Virchow found in Upper Silesia: our current pandemic has a social model.
This remains one of the few ubiquitous observations that systematically describe the risks of infection, hospitalizations and death from Covid-19 around the world. Yet while wealth correlates with those who can work from home and shop online in wealthy countries, it does less to explain patterns among the larger aggregates of people across states and nations. At this level, it seems that the most salient characteristics that distinguish the severity of a pandemic are relational factors such as economic equality and social trust. It is not surprising, even to the casual observer, that the pandemic has hit countries embroiled in political divisions and social strife most fiercely.
For example, consider the number of excess death across countries during the pandemic. If we look at the most severely affected countries, such as Peru, Bolivia, South Africa and Brazil, we see mainly middle-income countries in political turmoil and with weak social institutions. In contrast, countries that have experienced fewer deaths than expected based on pre-pandemic trends are often richer, but also stand out with high levels of political cohesion, social trust, income equality and collectivism, such as New Zealand, Taiwan, Norway, Iceland, Japan, Singapore and Denmark. Many researchers have come to similar conclusions in research conducted within and between countries on measures of political polarization, share capital, trust in government and income inequality.