"The analysis shows the infection events of the first three Corona waves in detail," said Mayor Katja Dörner. She thanked all those involved who contributed to the success of this project: "Bonn is thus a model city for microgeographic corona analyses. The insights gained can serve as helpful guidance for us and for other municipalities in dealing with the pandemic and evaluating concrete measures to be taken."
"In close collaboration with the city of Bonn, infas 360 and the Hygiene Institute of the University Hospital of Bonn, it was possible for the first time to analyze in depth the entire incidence of infection with additional data on the basis of anonymized index cases. In the process, clusters and patterns in certain population groups were identified, which serve to derive and also further develop targeted measures to combat the pandemic," say Dr. Barbara Wawrzyniak, head of data and analyses at Infas360, and Prof. Nico T. Mutters, director of the Hygiene Institute at the UKB, in solidarity.
The data basis
The Federal City of Bonn provided infas360 and the UKB with around 14,500 anonymized data records from the period between the end of February 2020 and the beginning of July 2021. The information on infection cases was recorded, enriched and analyzed with further sociodemographic and microgeographic data, and placed in context with the first three infection waves.
Wave 1: February 28, 2020 to April 30, 2020.
Wave 2: October 1, 2020 to February 28, 2021
Wave 3: March 1, 2021 to May 31, 2021.
This provided evidence-based insights into the content as well as spatiotemporal clustering of infections and their associations. The goal was to track the spread of Corona in greater depth regionally and derive insights for future action. The key findings can be summarized in several key messages.
"Analysis of the data has shown us that the virus reacts differently with each wave, but is becoming more predictable with progressive vaccination and the information we have," said Bonn's Health Director Margarete Heidler. "Our job is to use the information we have and the options available to us under the law in the best possible way to protect Bonn's population. I thank everyone involved for their commitment to this project, which I don't take for granted."
Second wave hit older, third wave younger people
At the beginning of the pandemic, the coronavirus spread across the working-age population (up to 65 years). In the second wave of infection, infections occurred more in the oldest segment of the population. With the third wave, the incidence of infection shifted to younger people, especially children and adolescents.
People in institutions significantly more at risk
During the period studied, four percent of the population in Bonn became infected with Corona. It was found that the incidence of infection was higher for people in old people's homes and nursing homes, where more elderly people also died compared to the other population groups.
Correlation with building and social structure
In the microgeographic analysis, the correlation between the infection figures and the building and social structure, which has already been shown for other cities, was confirmed. While in the first wave the well-off neighborhoods (low building density, high purchasing power, low proportion of people with a migration background) were more affected, in the second and third waves more infections occurred in the more poorly off neighborhoods (high building density, lower purchasing power, high proportion of people with a migration background). In addition, the larger the household, the greater the risk of infection.
Infections mostly within a social group
The analyses showed that infections occur almost exclusively within a social group. This enables targeted education and measures to stop infection chains. Infection events between people are concentrated in the same age group or infection between parents and children - i.e., the neighboring generation.
"The deeper analysis of infection trajectories and data confirms our previous work. The combination of our case data and the sociogeographic information available to infas 360 enables us to draw conclusions about the population groups that are particularly affected and the spatial distribution of infections," says Dr. Susanne Engels, head of the Bonn Health Department.
Various building blocks of urban measures
With further mobile vaccination and education offers, the Federal City of Bonn would like to reach its inhabitants and encourage them to be vaccinated, which is still the safest protection against severe courses of the disease. In particular, institutions such as nursing homes and homes for the elderly are closely monitored and help is offered in organizing and carrying out booster vaccinations. A close exchange with the Association of Statutory Health Insurance Physicians and the physicians in private practice makes it possible to react quickly to local problems and to contain the incidence of infection. Regular PCR tests (so-called lollipop tests) at all elementary schools and municipal daycare centers, as well as consistent contact tracing, provide the best possible protection for the group of children under the age of 12, who have not yet been protected by vaccinations.
The analysis of the incidences, the development of the infection figures within the individual population groups as well as the hospital occupancy is a further component of the municipal measures in the fight against the virus.
"The pandemic shows that it is important to conduct data collection and look more closely at the behavior and circumstances of affected people in order to initiate necessary measures. This is an important approach to prevention and health promotion in population medicine, which is the focus of public health departments," said Dr. Susanne Engels, head of the Bonn public health department.
Beginning in 2021, the city's crisis team regularly discussed best-practice models for dealing with the Corona pandemic with an interdisciplinary team from academia and research. To identify targeted measures, this exchange led to the commissioning of a small-scale analysis of Bonn's infection incidence in July 2021 by the infas360 research institute in cooperation with the Institute for Hygiene and Public Health at Bonn University Hospital. Bonn is acting as a model city in order to gain evidence-based insights for the future handling of the pandemic - also for other municipalities.
Translated with www.DeepL.com/Translator (free version)