example that immunization rates in Württemberg's Jaxt district were ≈40% higher than in the ... duchy of Baden. ... and Württemberg after an outbreak in France.
Katharina Muehlhoff, Universität Mannheim and Universität des Saarlandes
Attention: This poster is a challenge. It will confront you with the main questions of the corresponding paper: How to control epidemic infectious diseases by optimal prevention? Which institutions guarantee high immunization coverage? But, it will not give you the answers at once. Instead, you will assume the role of a 19th century health planner and take decisions which will earn you points. At the end, your score in the solution manual will indicate whether you would have prevented an epidemic and you will —hopefully— have learnt a lot about the interaction between geography, politics and the economical control of infectious diseases. Ready? Then let us travel back in time to 19th century Germany…..
Introduction: Smallpox— the Challenge
Immunization
Are you afraid of Ebola or MERS? Then take a minute to consider a disease as deadly as Ebola but infinitely more contagious: Smallpox. In preindustrial Europe, up to 75% of each cohort contracted smallpox and 8% succumbed to the disease. In 1800, English historian Macaulay wrote:
How do you attain high vaccination rates? A)You make vaccination mandatory by law.
(Continue at A)
B) You refrain from coercion—smallpox is a horrible disease and reasonable people will get vaccinated anyways. (Continue at B)
The smallpox was always present, filling the churchyards with corpses, tormenting with constant fears all whom it had stricken, leaving on those whose lives it spared the hideous traces of its power, turning the babe into a changeling at which the mother shuddered, and making the eyes and cheeks of the bighearted maiden objects of horror to the lover.
A
You have chosen to leave vaccination voluntary. This policy has been adopted by many European countries, including England and Prussia. Although there has been little initial difference in the immunization rates of states with and without mandatory vaccination., a gap appeared as large outbreaks became rare. At this stage, herd immunity was seldom realized under laissez-faire policies. Look right for a comparison between a vaccinating state (Baden) and a laissez-faire state (France).
These horrors were only banned in 1798 when Edward Jenner discovered the possibility to induce immunity against smallpox by inoculating patients with cowpox, a much less virulent disease. As trade and labor mobility were increasing rapidly, vaccination promised enormous economic and strategic benefits. But how to enforce universal immunization at reasonable costs?
Methodology: Modelling Epidemics The SIR model depicts how epidemics react to medical intervention. If it is incorporated in an economic optimization problem, the characteristics of optimal prevention can be derived analytically and graphically:
B
Mandatory vaccination. brings you in line with a number of German states including Baden, Wurttemberg and Bavaria. A major advantage of this strategy is that universal immunization leads to “herd immunity”, i.e. to a state in which the disease cannot spread within the population. You can assess the benefits of high vaccination rates by using an epidemiological (SIR) infection model. The model divides the population in three groups, namely of those susceptible (S), infected (I), and recovered (R). The dynamics of the epidemic process are captured by a set of differential equations which describes the movements between the three states.
Higher Levels of Prevenion
Information: II
Prevention effort reduces the final size of an epidemic.
Prevention reduces the maximum number of infections more than proportionally .
If prevention efforts in country i and country j are substitutes, there will be a prevention externality. The distortion grows the more dissimilar the countries are.
No matter whether compulsory or not, getting the public informed about vaccination was (and still is) a cornerstone of prevention policies. How do you disseminate fundamental medical knowledge?
I
How do you disseminate fundamental medical knowledge?
I: Total Infections
A) You rely on popular media like newspapers (Continue at A) B) You enlist the support of local elites like teachers, doctors and clergymen to increase popular reliance on vaccination. (Continue at B) C) You save the money, because you have made vaccination compulsory. (Continue at C)
II: Maximum Infections
A
You have chosen to promote vaccination by means of media coverage. This is not a bad idea, but it comes with pitfalls. Traditional and belief-based fears were common among the peasantry and the city poor – i.e. among people who were hardly reached by printed media. A doctor wrote: "The following prejudice is deeply rooted [in popular opinion], that vaccination will eventually give rise to other diseases even if it might prevent the outbreak of smallpox." (Archival Source GLA Karlsruhe) A pastor from the city of Mannheim added: Most members of the parish are poor and especially the heads of large families secretly welcome the disease. For, if the smallpox take one child or another, they are relieved of a burden and can place the guilt of their children’s death on God.” (Archival Source GLA Karlsruhe)
C
You have chosen to refrain from information activities. Unfortunately, this strategy did not address popular fears and gave rise to vociferous antivaccination movements. Once these groups had formed, they were ubiquitous in popular media and universal immunization was virtually unfeasible.
B
Immunization was typically most successful when its proponents engaged in face-to face communication and set positive examples by local elites. This was an inexpensive and efficient way to make vaccination popular. Note for example that immunization rates in Württemberg‘s Jaxt district were ≈40% higher than in the rest of the country because local teachers and pastors lobbied actively for vaccination.
Contemporary print suggesting that vaccination tiggered diseases like plague, leprosy etc.
Implementation:
Let us assume you have successfully introduced vaccination. The sustained success of your policy depends on your ability to ensure doctors can perform and patients will receive vaccinations at modest costs.
A
Your solution involves a network of public doctors who conduct mass -vaccination campaigns. This approach was followed by the Grand duchy of Baden. The system was highly predictable and made vaccination a generally accepted habit.
How do you make sure everybody actually gets inoculated? A)You hire public doctors who conduct mass vaccination campaigns once or twice a year. The right to vaccinate is restricted to academically trained doctors. (Continue at A) B) You seek to spread immunization as fast and cost-efficiently as possible. Therefore you expand the permission to vaccinate to surgeons, midwives and even trained laymen. (Continue at B)
B
Like the government of Württemberg, you opted for a decentral system. Unfortunately, this was not as flexible and costless a solution as it seems. The reason was that the cowpox vaccination often failed to produce a sufficient immune reaction. Thus, the vaccination marks had to be controlled some days after inoculation. Especially in rural areas, doctors were reluctant to do so, because the ways to reach patients were long and cumbersome. As a country doctor observed:
Villagers gathering in the local school to have their children vaccinated
The fact that doctors were hired, salaried and controlled by the state also helped to ensure that inoculation was performed according to the state of medical art.↔ Low enforcement costs in the long run.
Running a medical practice in the countryside presents far greater a challenge than practicing in the city. There was rarely any night which passed without the door-bell ringing me out of bed and calling me to visit a patient in some village; there was no way, I could have eaten my meals at regular hours and in the end, even my horse could no longer bear the daily drudgery so I needed to buy a second one .”(A. Kussmaul, Erinnerungen, Stuttgart 1899, p. 109).
Infrastructure
Consequently, vaccinations were often not properly performed and documented unless doctors were rigorously controlled by central agencies. In decentralized systems like Wurttemberg, vaccinating patients in remote areas was often left to surgeons or more or less qualified laymen. The lack of control often produced undesired side-effects including the transmission of other diseases through contaminated instruments or the use of real smallpox lymph. To get a flavor of these pain costs, consider an illustration of a 19th century medical textbook..↔ High enforcement costs and poor prevention coverage in the long run.
A&B
Results – Lessons of Past Epidemics:
Successful immunization requires centralization, coordination and investment in information and infrastructure. Why did countries like Baden undertake these investments while others like Württemberg did not? The answer is, that countries which were exposed to imported epidemics were more eager vaccinators than states which had a shield of vaccinating states around them. The benefits of universal immunization were drastically revealed by a smallpox pandemic which broke out after the Franco-Prussian War. Since the German states 1800-1870
Level of Observation
German States and Prussian Provinces
Variable
Coefficient
Std. Err.
z
P>|z|
Exposure
0.0033
.0012
2.51
0.01
Shield
-1.2628
.5467
-2.31
0.02
River
0.0008
.0004
2.00
0.03
Pseudo R2
0.22
Variable
Description
Exposure
Exposure gives the length of a state's borders in relation to its surface.
Shield
Shield is a binary variable which takes the value of 1 if an adjacent state of country i
How do You make sure that outbreaks are reported and doctors are provided with vaccine? A) You create central institutions which produce vaccine.
correspond to a central-
ized strategy followed by the Grandduchy of Baden. The country established “vaccination institutes” (Impfinstitute) which collected lymph to produce fresh vaccine. The vaccination institutes were located at strategic positions to allow prompt delivery of vaccination lymph to any district in the country. The network of public doctors then guaranteed that mass-vaccinations could be performed within 1 or 2 days (!) after an unexpected epidemic outbreak.
The SIR model predicts that comprehensive prevention reduces the expected size of an epidemic more than proportionally.
Observation Period
Successful disease prevention is a matter of high vaccination coverage as well as rapid detection and containment of outbreaks.
B) You facilitate communication between local and central agencies. C) You require doctors to collect their own vaccine. D) You fine individuals who fail to report a case of smallpox.
C&D
capture the more decentralized strategies of Wurttemberg and other German states. Even if some of them had introduced mandatory vaccination, lack of vaccine or sluggish communication often helped epidemic spread. To see this, consider smallpox prevalence in Baden (centralized system) and Württemberg after an outbreak in France.
Outbreak in Alsatia (France)
has implemented mandatory vaccination laws and zero otherwise River
River denotes the length of navigable rivers in a state's territory.
which enforced vaccination by law weathered the epidemic comparatively well, the German Empire reacted by passing the Reichsimpfgesetz (National Vaccination Law) soon after its formation in 1871.
Source: Archival Sources, Generallandesarchiv Karlsruhe, Académie de la Médicine, Paris
Policy Implications: Mandatory vaccination facilitates high immunization coverage, but it is no sufficient condition. Other contributing factors are:
Smallpox Mortality and Vaccination Policies , Source: Mitteilungen aus dem Reichsgesundheitsamt, various years .
Rigorous information campaigns
Supervision and prompt supply of safe vaccine
Centralization and (international) coordination to reduce prevention exteralities.
Given that many German states did not take these steps prior to the 1870-74 pandemic, history suggests that the the heighted interest in current health threats like Ebola ought to be channeled into initiatives for multilateral health institutions, binding commitments to immunization and documentation targets and cooperation in the containment of outbreaks .
