Results of the “Heinsberg study” published
The district of Heinsberg in North Rhine-Westphalia in Germany is the focal point for the novel coronavirus SARS-CoV-2. After a carnival session, there was an early and massive spread of the pathogen in Germany. As part of the study, a research team led by Prof. Dr. Hendrik Streeck and Prof. Dr. Gunther Hartmann from the University of Bonn in the village of Gangelt interviewed a large number of residents, took samples and analyzed them.
The mortality rate in the spotlight
Among other things, the mortality rate of the infection was precisely determined for the first time. The results of the study have been published in advance and are now being presented to science and the public. A publication in a peer-reviewed journal follows.
The focus of the study is the infection fatality rate (IFR), which indicates the proportion of deaths among those infected. This must be differentiated from the case fatality rate (CFR). The IFR is the more reliable parameter for various reasons, and its determination is required internationally for SARS-CoV-2.
“With our data, it is now possible for the first time to estimate very well how many people have been infected after an outbreak event. In our study, that was 15% for the community of Gangrel. Infection mortality (IFR) can be determined by the total number of all infected people. For SARS-CoV-2, it is 0.37% for the outbreak in the community of Gangelt, ”says study leader Prof. Dr. Hendrik Streeck, director of the Institute of Virology at the University Hospital Bonn.
The basis for model calculations
With the IFR, the number of people who have died can be used to estimate how many people are infected in other places with different infection rates. The comparison of this number with the number of officially reported infected leads to the so-called dark figure. In Gangelt this is around 5 times higher than the officially reported number of people who tested positive. If one extrapolates the number of almost 6,700 SARS-CoV-2-related deaths in Germany, the estimated total would be around 1.8 million infected. This undisclosed figure is 10 times greater than the total number of officially reported cases (162,496 on May 3, 2020).
“The results can be used to further improve model calculations on the spreading behavior of the virus – so far the data basis has been comparatively uncertain,” says co-author Prof. Dr. Gunther Hartmann, head of the Institute for Clinical Chemistry and Clinical Pharmacology at the University Hospital Bonn and spokesman for the Cluster of Excellence ImmunoSensation.
The study also provides important information for further research on SARS-CoV-2, such as the risk of infection depending on age, gender, and previous illnesses, the higher severity of the disease under the special conditions of a massive infection event such as Gangrel, or the risk of infection within families.
20% to 25% of COVID-19 infections are completely asymptomatic
The description of symptoms is also an aspect of the study. The most striking symptom complex for this infection is the loss of smell and taste previously described by Prof. Streeck. Besides, a total of 22 percent of all infected people in Gangelt showed no symptoms at all. It was noticed that people who had attended the carnival session had symptoms more often. “To find out whether physical proximity to other meeting participants and increased droplet formation through loud speaking and singing have contributed to a stronger course of the disease, we are planning further examinations in cooperation with specialists in hygiene,” explains Prof. Hartmann.
“The fact that every fifth infection has no noticeable disease symptoms suggests that it is not possible to reliably identify infected people who can secrete the virus and thus infect others based on recognizable symptoms,” says Prof. Martin Exner, head of the Institute for Hygiene and public health and co-author of the study. This confirms the importance of the general distance and hygiene rules in the corona pandemic. “Every supposedly healthy person we meet can unwittingly carry the virus. We have to be aware of this and act accordingly, ”says the hygiene expert.
In the multi-person households examined, the risk of catching another person was surprisingly low. “The infection rates in children, adults, and the elderly are very similar and do not depend on age,” says Prof. Streeck. There are also no significant differences between the genders.