Seroprevalence of Anti-SARS-CoV-2 IgG Antibodies in Tyrol, Austria: Updated Analysis Involving 22,607 Blood Donors Covering the Period October 2021 to April 2022
Lisa Seekircher,
Anita Siller,
Manfred Astl,
Lena Tschiderer,
Gregor A. Wachter,
Bernhard Pfeifer,
Andreas Huber,
Manfred Gaber,
Harald Schennach,
Peter Willeit
Affiliations
Lisa Seekircher
Clinical Epidemiology Team, Medical University of Innsbruck, 6020 Innsbruck, Austria
Anita Siller
Central Institute for Blood Transfusion and Immunology, Tirol Kliniken GmbH, 6020 Innsbruck, Austria
Manfred Astl
Central Institute for Blood Transfusion and Immunology, Tirol Kliniken GmbH, 6020 Innsbruck, Austria
Lena Tschiderer
Clinical Epidemiology Team, Medical University of Innsbruck, 6020 Innsbruck, Austria
Gregor A. Wachter
Central Institute for Blood Transfusion and Immunology, Tirol Kliniken GmbH, 6020 Innsbruck, Austria
Bernhard Pfeifer
Tyrolean Federal Institute for Integrated Care, Tirol Kliniken GmbH, 6020 Innsbruck, Austria
Andreas Huber
Tyrolean Federal Institute for Integrated Care, Tirol Kliniken GmbH, 6020 Innsbruck, Austria
Manfred Gaber
Blood Donor Service Tyrol of the Austrian Red Cross, 6063 Rum, Austria
Harald Schennach
Central Institute for Blood Transfusion and Immunology, Tirol Kliniken GmbH, 6020 Innsbruck, Austria
Peter Willeit
Clinical Epidemiology Team, Medical University of Innsbruck, 6020 Innsbruck, Austria
Because a large proportion of the Austrian population has been infected with SARS-CoV-2 during high incidence periods in winter 2021/2022, up-to-date estimates of seroprevalence of anti-SARS-CoV-2 antibodies are required to inform upcoming public health policies. We quantified anti-Spike IgG antibody levels in 22,607 individuals that donated blood between October 2021 and April 2022 across Tyrol, Austria (participation rate: 96.0%). Median age of participants was 45.3 years (IQR: 30.9–55.1); 41.9% were female. From October 2021 to April 2022, seropositivity increased from 84.9% (95% CI: 83.8–86.0%) to 95.8% (94.9–96.4%), and the geometric mean anti-Spike IgG levels among seropositive participants increased from 283 (95% CI: 271–296) to 1437 (1360–1518) BAU/mL. The percentages of participants in categories with undetectable levels and detectable levels at p-value < 0.001). In conclusion, anti-SARS-CoV-2 seroprevalence in terms of seropositivity and average antibody levels has increased markedly during the winter 2021/2022 SARS-CoV-2 waves in Tyrol, Austria.
