Assessing SARS-CoV-2 Prevalence in Austria with Sample Surveys in 2020-a Report

Since the beginning of the SARS-CoV-2 pandemic a main metric is the amount of infected people at any given time. We present a valid assessment of the population acutely infected by SARS-CoV-2 in Austria at three distinct points in time: April, May and November 2020. The population of these sample surveys includes people aged 16 or older living in private households. Participants were tested with PCR (polymerase chain reaction) tests using nose-throat swabs. Based on these tests, it is assumed that the number of acute SARS-CoV-2 infections was below 11,000 individuals, or 0.15% of the target population, in April, below 6,000, in May and below 265,000 in November (i.e. the upper limit of the 95% confidence interval). In November a comparison with the Austrian Epidemiological Reporting System reveals that more than estimated 50% of acute infections remain undetected by the official reporting obligations.