1
|
Seekircher L, Siller A, Astl M, Tschiderer L, Wachter GA, Pfeifer B, Huber A, Gaber M, Schennach H, Willeit P. 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. Viruses 2022; 14:1877. [PMID: 36146684 PMCID: PMC9502884 DOI: 10.3390/v14091877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 08/19/2022] [Accepted: 08/22/2022] [Indexed: 11/30/2022] Open
Abstract
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 <500, 500−<1000, 1000−<2000, 2000−<3000, and ≥3000 BAU/mL were 15%, 54%, 15%, 10%, 3%, and 3% in October 2021 vs. 4%, 18%, 17%, 18%, 11%, and 32% in April 2022. Of 2711 participants that had repeat measurements taken a median 4.2 months apart, 61.8% moved to a higher, 13.9% to a lower, and 24.4% remained in the same category. Among seropositive participants, antibody levels were 16.8-fold in vaccinated individuals compared to unvaccinated individuals (95% CI: 14.2−19.9; 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.
Collapse
Affiliation(s)
- 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
- Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, 3584 CX Utrecht, The Netherlands
| | - 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
- Division for Healthcare Network and Telehealth, UMIT-Private University for Health Sciences, Medical Informatics and Technology GmbH, 6060 Hall, 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
- Department of Public Health and Primary Care, University of Cambridge, Cambridge CB1 8RN, UK
| |
Collapse
|