The national immunization registry serves as the source for the vaccination data. The cases of SARS-CoV2 infection registered in the epidemiological reporting system EMS are regularly supplemented with the vaccination data via a reliable person identifier. The data quality assurance necessary for this is performed by the Institute of Infectious Epidemiology of AGES. The definition of sufficient and insufficient vaccine- or/and infection-induced immunization, based on the information on COVID19 vaccination and SARS-CoV2 infection history and their temporal sequence, is derived from the evidence-based vaccination recommendations of the NIG, according to the document "COVID-19 Vaccinations: Application Recommendations of the National Immunization Panel (as of Dec. 23, 2021), is derived. Immunization classification refers to status at the time of current laboratory diagnosis of SARS-CoV-2 infection. The reference population used in this report for 2021 was the population as provided by Statistics Austria at the beginning of 2022. A relevant limitation for all analyses of infection incidence by vaccination/genese status is the different testing strategy between vaccinated/genese individuals and all other individuals classified as not or not sufficiently immunized. The latter group of individuals has a higher likelihood of being detected as a case of asymptomatic SARS-CoV-2 infection due to access testing obligations compared with individuals classified as adequately immunized who are not subject to these testing obligations; this may lead to an underestimation of the true incidence of asymptomatic infection among the vaccinated, geneseeded, and geneseed-vaccinated. Because the analysis is based on symptomatic infection, the impact of this limitation on the infection risk ratio result by immunization classification should be smaller. We hypothesize that for suspected COVID-19 sufferers, the likelihood of being identified as a case of SARS-CoV-2 infection is largely independent of vaccination status or genesee status.

A. CHALUPKA, N. HANDRA, L. RICHTER, D. SCHMID.