As the world grapples with the COVID-19 pandemic, the history of infectious diseases has attracted renewed attention. The stark social disparities laid bare by the current pandemic induce us to unearth teachable lessons from the past about the impact of earlier epidemics on different parts of the population. Many newspaper articles, opinion pieces and scholarly papers have centred on the bubonic plague outbreaks of the fourteenth to the seventeenth century, unparalleled as this disease was in its death toll and societal effects. The Spanish Flu of 1918-1919 has similarly played an important role, due to its relative historical nearness and the rich documentary trail of photographs, pamphlets and reports. In both cases, scholars have pointed to differences in disease burdens across regions, between urban and rural locations, occupations, wages or incomes, age, gender, and race. In spite of what one might aspect from these highly lethal epidemics, research has indicated that they did discriminate – very much like on-going research on COVID-19 is showing today. Smallpox, on the other hand, is a disease that has so far largely escaped this revived interest. This is surprising, because smallpox was the first contagious disease for which a vaccine was developed and its history provides important lessons about how social inequalities continue to shape vulnerability to disease in societies lacking universal uptake.
For centuries, smallpox was one of the deadliest and most widespread of all infectious diseases. It was transmitted by airborne droplets and the pus from pustules of an infected person. The first symptoms would often consist of muscle and joint pain, fatigue, high fever, nausea and vomiting, followed by a rash covering the entire body. In many cases, blisters developed, which turned into scabs that left scars. Levels of mortality were high: smallpox killed around 25 to 40 per cent of those infected. Anyone who survived infection possessed lifelong immunity. This resulted in a substantial level of immunity among large parts of the European adult urban population, while especially children and migrants from the countryside were susceptible. Before the era of widespread vaccination, smallpox would often erupt as a substantial epidemic at least once in a lifetime.
Edward Jenner’s inoculation of a 13 year-old-boy with cowpox in 1796 famously led to the creation of the smallpox vaccine: the first vaccine to ever be developed against a contagious disease. Large-scale vaccination campaigns subsequently commenced in Western countries like the Netherlands in the early 1800s, ultimately culminating in its global eradication in 1979. Alongside preventative measures, cowpox vaccination significantly reduced the frequency and severity of smallpox outbreaks. Yet, by 1870, increased urbanisation and global connectedness, waning vaccination levels, and the mobilisation and concentration of people due to the Franco-Prussian war led to a massive smallpox pandemic that spread between European countries and eventually reached Asia via America. It was the last smallpox epidemic to reach pandemic level across Europe and was the first to be studied scientifically by contemporaries, resulting in an unprecedented degree of documentation upon which we can draw today. Figure 2 illustrates the terrible shock that people must have felt, witnessing once more an outbreak that was only comparable in fatalities to ones occurring more than 70 years earlier. Although Amsterdam was not one of the cities hit hardest by the epidemic, it still lost about 1 in 125 inhabitants to the disease. The greatest blows were served to infants aged between 0 and 4. This age group was most vulnerable to an outbreak because they were the most likely to not have been vaccinated yet, nor had they had the chance to survive smallpox in the past.
Who were these victims? Did all of Amsterdam’s population face equal risks during the epidemic? Both scholars and nineteenth-century doctors have been inclined to assume that smallpox is a ‘socially neutral’ disease. Infection could simply seem unavoidable due to the mode of transmission (through air and close personal contact), striking lower and higher classes fairly equally. Some scholars have, however, suggested that socio-economic status did matter. Differences in living standards, housing and house density, and opportunities to keep distance from infected people could reduce or increase the impact of a smallpox epidemic on particular parts of the population. Faced with an outbreak, the higher classes had better opportunities to isolate infected household members in separate rooms. This was impossible for a large part of the population: families that shared a single room of less than 10 square metres, in a building occupied by up to 12 families. Furthermore, it is generally assumed (though not corroborated by archival evidence) that vaccination campaigns were less successful at the bottom of the societal ladder. All of this makes an examination of the last smallpox epidemic in Amsterdam between 1870 and 1872 in relation to social inequalities worthwhile.
Significant social and spatial disparities existed between different parts of the city. At the time of the smallpox epidemic, the city of Amsterdam was divided into fifty administrative neighbourhoods with an average of just over 5,000 inhabitants. Even prior to the epidemic, nineteenth-century doctors debated how the composition of Amsterdam’s neighbourhoods might affect disease and mortality patterns. For example, neighbourhoods D and E in the heart of the city (see Figure 4) were considered to be better-off, and were characterized by relatively good health conditions. The opposite was true for many neighbourhoods belonging to the Jordaan (neighbourhoods QQ, PP, OO, NN, MM, DD, EE, FF and GG), which were infamously poor and unhealthy and contained hundreds of alleyway slums. How did the inhabitants of these different neighbourhoods fare during the smallpox epidemic of the 1870s? Was smallpox as undiscriminating as commonly believed, or did the spread and distribution of smallpox mortality reveal social inequalities?
Smallpox entered the city of Amsterdam in April 1870, months before the Causes of Death registers (recently digitised the Radboud Group Citizen Science for the History of Health) recorded its first fatal victim. The city’s annual report of 1870 describes how all of the initial cases of smallpox were found in the old city centre (see Figure 4, phase 1). Government officials were worried about the increase of smallpox cases and initially traced them back to foreign contacts: recently returned travellers and those “for whom their occupation necessitated contact with the French”. The spread of smallpox from the old city centre to the rest of the city (phase 2) was accompanied by the first fatalities of the unfolding epidemic in November. In December, 49 cases were reported, with 11 casualties; more than half of which were now observed outside of the old city centre. By this time, the medics ceased to report on external sources of smallpox, as it had become clear that new infections now came from within the city itself. The Causes of Death registers reveal that smallpox swept across the whole city during 1871, killing, at its peak, 24 inhabitants a day (phase 3). The disease started to phase out during the early months of 1872 (phase 4), although it took until the end of the year for deaths to cease in all neighbourhoods (phase 5). Smallpox clearly lingered the longest in the poorest parts of Amsterdam.
An examination of the neighbourhoods most affected by the epidemic reveals a clear picture of spatial differentiation. Figure 5 shows the smallpox death rate per 1000 inhabitants of Amsterdam’s fifty neighbourhoods in the worst year of the epidemic, 1871. The use of death rates rather than the death counts allows us to correct for the varying population sizes of the neighbourhoods. If chances to succumb to smallpox were equal across Amsterdam’s urban landscape, the height of the bars would not substantially differ between one neighbourhood and another. But this was not the case. On the contrary: Figure 5 reveals vast variation in smallpox mortality. The neighbourhoods with the highest smallpox deaths had double or triple the mortality rate of the neighbourhoods with the lowest. Moreover, the colour-coding of each neighbourhood according to wealth categorisation reveals something similar to a coarse social gradient: neighbourhoods that did relatively well during the epidemic were by and large also those that were regarded as being among Amsterdam’s wealthiest. And vice versa, neighbourhoods with very high smallpox death rates belonged to the poorest neighbourhoods. The pattern is only really disrupted by the Jewish neighbourhoods, which did exceptionally well regardless of their infamous poverty and crowdedness.
The spatial distribution of smallpox deaths lays bare some of the deep-seated social and health inequalities across the city of Amsterdam. Many factors may have contributed to the stark neighbourhood variation in smallpox mortality – some quantifiable, others less so. The number of inhabitants per house and neighbourhood wealth had a significant and measurable effect on smallpox mortality. Higher birth rates in the poorer areas, furthermore, made for a larger young population susceptible to smallpox. We lack data on neighbourhood vaccination rates, but the relative success of the Jewish neighbourhoods (often lauded for their high vaccination uptake) during the epidemic is suggestive of its importance. The case-study of the last Dutch smallpox epidemic emphasises once more that the outcome of an epidemic is not only a matter of biology. It highlights how socially and economically deprived populations are more vulnerable to the burden of epidemics, in the past as much as today. Moreover, it also suggests that in certain circumstances these disadvantages may be offset by particular interventions such as vaccination. The historical example of the smallpox epidemic therefore underscores the importance of addressing and tackling existing inequalities in today’s COVID-19 control strategies. As research is suggesting, failing to do so will only further exacerbate health disparities for future generations.
Further reading
Sanne Muurling, Tim Riswick, and Katalin Buzasi, ‘The Last Dutch Smallpox Epidemic: Infectious Disease and Social Inequalities in Amsterdam, 1870-1872’, SocArXiv (25 June 2021). doi:10.31235/osf.io/szjp5.
Tim Riswick is a historical demographer working as a postdoctoral researcher at Radboud University. His research focuses on the impact of kin on child mortality outcomes, inequality in cause-specific mortality risks, and comparative historical life course research on East Asia and Western Europe. He tweets as @timriswick.
This research has been conducted as part of the project Lifting the Burden of Disease. The modernisation of health in the Netherlands: Amsterdam 1854-1940, led by Prof. dr. Angélique Janssens and Prof. dr. Jacco Wallinga, and was funded by the Dutch Research Council (NWO).