In December 2019, the novel coronavirus SARS-CoV-2 with the accompanying severe respiratory disease COVID-19 emerged in Wuhan Province, China, and quickly spread around the world. Since then, measures such as exit restrictions have been introduced in many countries to contain the pandemic – including Germany. This has been done in an attempt to contain the spread of the virus in order to protect vulnerable groups such as the elderly, the immunocompromised and people with pre-existing conditions, and to avoid overburdening the healthcare system. These measures are continuously adjusted taking into account the incidence of SARS-CoV-2.

Scientific data indicate that a large proportion of infected persons, however, do not show typical symptoms of the disease and are thus not recorded in the reporting statistics. As a result, the actual number of cases, the immunity to SARS-Co-V-2 that presumably accompanies them, and the mortality rate are unknown. These parameters play an important role in assessing and forecasting the further course of the epidemic in Germany and should provide information and recommendations for policy makers.

To be able to determine the actual spread of the virus, there is the possibility to test the blood serum for antibodies against SARS-CoV-2. These antibodies are produced shortly after infection by the human immune system and remain in the body even after the disease, and can thus react faster and better to the virus in case of a new infection, presumably providing immunity. How long the immunity lasts is still unclear and can be found out with this study.

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