Summary in English:

Natural immunisation, vaccination and risk for COVID-19 by age in Switzerland.

Brian Martin^a,b, Eva Martin-Diener^b, Pirmin Schmid^a, Thomas Bührer^a, Andreas Stettbacher^a
a Military Health Service, Swiss Armed Forces; ^b Epidemiology, Biostatistics and Prevention Institute of the University of Zurich

In June 2021, the COVID-19 incidence in Switzerland continues to fall, and there is a growing body of evidence concerning the immune response to COVID-19 infections. At the same time, the national vaccination campaign is well underway. As long as no new variants of SARS-CoV-2 with relevant immune escape are emerging, it can be assumed that individuals who have recovered from COVID-19 are largely protected from re-infection for about 6 months, individuals who are fully vaccinated for at least 12 months. The data are updated weekly by the Swiss Federal Office of Public Health. They can be used to re-define the population at risk and to calculate age-specific incidences adjusted for natural immunisation, vaccination and both. The Swiss Armed Forces do so to inform the adjustment of protective measures, of the COVID-19 test strategy, of contact management and of the vaccination strategy. In the beginning of June 2021, unvaccinated individuals of the age of 80 years or more in Switzerland still had a 14 day incidence for COVID-19 higher than that of the general population. This fact indicates the continuing importance of vaccinations as  well as the protection of the unvaccinated. The quantification of COVID-19 risks is essential for counselling individual patients as well as for designing targeted measures to protect specific population groups, for example members of the Armed Forces.