Smallpox vaccination in 19th-century Finland: lessons from a vaccine mandate

Susanna Ukonaho. Show Author details

Poor vaccine uptake limits the public health impact of vaccination campaigns and compromises the health of at-risk individuals. In high-income countries, the elimination of vaccine-preventable childhood infections fails and some infections are on the rise, a phenomenon in part attributed to persistent hesitancy towards vaccines. To combat vaccine hesitancy several countries including Italy (2017), France (2018) and Germany (2020) recently made vaccinating children mandatory, for example by allowing children to public schools only after vaccination or through fines, but the effect of such vaccination laws on vaccination coverage remains debated and their long-term consequences remain little known.

The history and resistance against vaccine mandates

In fact, although rarely studied, mandatory vaccination or vaccination mandates have a long history in Europe and the US. The earliest vaccination campaigns against the highly lethal childhood infection smallpox were already set during the 19^th century (see an earlier post here on smallpox in the Americas), soon after the development of the world’s first vaccine, by the British physician Edward Jenner in 1796 (Fenner 1988). In many countries vaccination mandates soon followed, for example as early as 1806 in parts of Italy, 1810 in Denmark, 1816 in Sweden, 1853 in England and Wales and 1874 in Germany (Salmon 2006, Petersen 1833). 

Along with other European countries, Finland’s vaccination campaign against smallpox started in 1802. In 18^th and 19^th century Finland, smallpox was a major cause of death in children, killing up to 15% of Finland’s population around 1800, before the introduction of vaccines (Mielke et al. 1984, Ketola et al. 2021, Briga et al. 2021). Although there was a great need for vaccines, the management of the vaccination campaign was poor at the beginning and struggled to meet the demands and standards of good quality vaccines. Despite the efforts, vaccination uptake did not consistently exceed 80 %, which is required for smallpox herd immunity. For this reason, Finland imposed a law in 1883 that made vaccination mandatory for all children over the age of 2. This law was reinforced with a fine. The last case of smallpox in Finland was diagnosed in 1941. In 1980, WHO declared smallpox eradicated from nature. 

Although the history of vaccination campaigns spans 200 years, the characteristics and impact of these campaigns have been rarely studied on the long-term. I studied the long-term consequences of Finland’s first vaccination campaign against smallpox by describing the timing and age at first vaccination and the impact of the 1883 vaccine mandate on vaccination uptake in Southwestern rural Finland. I acquired and digitised vaccination records from the Finnish National archives, which included close to 50,000 individuals monitored for 63 years from 1837 till 1899 in 8 rural Finnish parishes. Children were called for vaccination by their local priests, and they were also the ones who collected records consisting of personal details about the children and the success of the vaccination. The figure below illustrates what Finnish historical vaccination records look like. Columns represent (from left to right): I, ii, iii: Location, village and house; iv: Name and occupation of the parent (mother or father); v, vi: Names and birthdate of person called for vaccination; vii, viii: date of vaccination; ix, x: date of follow-up examination; xi-xiii: success of vaccination (successful, partial or no reaction); xiv-xv: absent from vaccination or follow-up examination. People who disagreed to vaccination are symbolised by ‘/’ or ‘x’ and do not have a date (not on this page); xvi: remarks and notes. In most cities and towns in Finland, vaccinators reported numbers of vaccinated at a municipality level as early as the vaccination campaign started but more detailed annual records started to become the norm around the 1830s or the 1850s at the latest, depending on the parish.

There was seasonal variation in the timing of vaccination, likely attributed to the fact that vaccinators travelled to the parishes only once a year during the summer, when farmers had more time to attend vaccination. Most people were vaccinated within the first year after birth, which is important to prevent childhood infections early on. Vaccination coverage before the mandatory law was on average 60 % and had been decreasing since the beginning of the campaign. This decrease stopped with the introduction of a mandatory vaccination law, after which vaccination rates increased abruptly to an average of 80 % which persisted for at least 15 years. 

The benefits of vaccine mandates 

According to historical records, the distribution and quality of vaccines as well as the management of the campaign in Finland gradually improved throughout the 19^th century (Björkstén 1902 & 1908). For example, vaccine distribution improved slowly but consistently especially after the establishment of a new vaccination district division and a new vaccine inventory for district doctors after 1825. In Finland, the smallpox vaccination campaign was met with high hesitancy from the public (Björkstén 1902 & 1908) and the opposition against vaccines remained strong throughout the progression of the campaign. There were efforts to reassure the public, which did not seem to work. Vaccination mandates against smallpox were common in many European countries already during the early 19^th century and following the lead from other countries, the Chief of Finnish doctors’ association first proposed mandatory vaccination in 1830, but the proposition was denied as unlawful and thought to raise further hesitancy and refusal among the public. 

After the famine years 1868-1869, which created a particularly good breeding ground for major smallpox outbreaks, as annual vaccinations ceased in many parishes, discussions about mandatory vaccination started again in the early 1880s. As a result, a vaccination mandate was proposed again and this time the proposition passed. The mandate was adopted in 1883 and it required parents to vaccinate children under the age of two (Björkstén 1908). 

Conclusions

In historical Finland, the vaccination law increased vaccination coverage over the long-term even in rural areas and during a period without proper health care, where vaccination campaigns even today often struggle with distribution issues and high reluctance. It should be noted that vaccine mandates improve vaccine uptake not only by highlighting the importance to vaccinate but also by increasing efforts in vaccine distribution and overall campaign management. However, in the case of smallpox, only the mandatory law was able to increase vaccination coverage over the required level for herd immunity, which is 80 %.

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