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SARS-CoV-2 Postvaccination Infections Among Staff Members of a Tertiary Care University Hospital – Vienna, January-July 2021; an Exploratory Study on 8 500 Employees with Better Outcome of Vector than m-RNA Vaccine

26 Pages Posted: 18 Aug 2021

See all articles by Sophie Brunner

Sophie Brunner

Medical University of Vienna - Division of Angiology

Tibor Spath

Medical University of Vienna - Vienna General Hospital

Gabriela Kornek

Medical University of Vienna - Vienna General Hospital

Bernhard Parschalk

Medical University of Vienna - Vienna General Hospital

Maximilian Schnetzinger

Medical University of Vienna - Vienna General Hospital

Robert Strassl

Medical University of Vienna - Vienna General Hospital

Rebeka Savic

Medical University of Vienna - Vienna General Hospital

Andrea Foit

Medical University of Vienna - Vienna General Hospital

Helene Resch

Medical University of Vienna - Vienna General Hospital

Florian Thalhammer

Medical University of Vienna - Vienna General Hospital

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Abstract

Background: The identification of SARS-CoV-2 antigen or RNA in a respiratory specimen collected from a person ≥14 days after completing all recommended doses of authorized COVID-19 vaccine series is a rare condition and defined as „breakthrough infection“. Data on mildly symptomatic or asymptomatic SARS-CoV-2 vaccine breakthrough infection cases especially with respect to viral characteristics and temporal relation to vaccination date is scarce. The purpose of the present investigation was to investigate the prevalence of postvaccination  infections in hospital employees and to compare between m-RNA and vector based SARS-CoV-2 vaccines.

Methods: At the General Hospital of Vienna 8 553 actively employed staff members participated at an voluntary in-house vaccination program, which took place between January and May 2021 and comprised of application of two doses of either COMIRNATY (BNT162b2; Pfizer/BioNTech, Inc.) or VAXZEVRIA (AstraZeneca, Inc.).

Findings: By the end of July 2021 a total of 78 postvaccination infection cases after administration of a minimum of one dose of vaccination had been identified (median age: 40·5 years (IQR: 19-60 years); 53 women) of whom 53 had been vaccinated with VAXZEVRIA and 25 with COMIRNATY. The majority of infections was related to an insufficient or partial vaccination status; the incidence of postvaccination infection ≥14 days after complete vaccination (i.e. breakthrough infection) was 34·8: 10 000 for COMIRNATY and 8·8: 10 000 for VAXZEVRIA. There was no difference in PCR-CT values between the two vaccine brands (24·67 (SD: 7·41) for VAXZEVRIA vaccinated versus 24·0 (SD: 6·53) for COMIRNATY vaccinated persons). Genotyping of positive PCR specimens revealed 42 variant of concerns: B.1.1.7 (n=34); B.1.351 (n=2), B.1.617.2 (n=6). The prevalence of „real brakthrough infections“ (≥14 days after second vaccination) was higher in COMIRNATY vaccinated subjects than in the VAXZEVRIA vaccinated subjects with a ratio of 14:4 (p<0,01). 

Interpretation: mRNA and vector vaccines against COVID-19 are both highly effective in protecting against a broad genomic spectrum of SARS-CoV-2 infections, at least with respect to severe illness. In the present investigation VAXZEVRIA was more effective than COMIRNATY with respect to prevent breakthrough infections after full immunization, however, it seems important, that all recommended vaccine doses are applicated. Maintaining distinct precautions and ongoing testing, at least for the immediate period after vaccination, to detect asymptomatic infections is highly recommended.

Funding: None to declare.

Declaration of Interest: We decline no conflicting interest.

Ethical Approval: The study was approved by the ethics committee of the Medical University of Vienna [No.1721/2021] and the medical directorate of the hospital.

Suggested Citation

Brunner, Sophie and Spath, Tibor and Kornek, Gabriela and Parschalk, Bernhard and Schnetzinger, Maximilian and Strassl, Robert and Savic, Rebeka and Foit, Andrea and Resch, Helene and Thalhammer, Florian, SARS-CoV-2 Postvaccination Infections Among Staff Members of a Tertiary Care University Hospital – Vienna, January-July 2021; an Exploratory Study on 8 500 Employees with Better Outcome of Vector than m-RNA Vaccine. Available at SSRN: https://ssrn.com/abstract=3907198 or http://dx.doi.org/10.2139/ssrn.3907198

Sophie Brunner (Contact Author)

Medical University of Vienna - Division of Angiology ( email )

Vienna
Austria

Tibor Spath

Medical University of Vienna - Vienna General Hospital ( email )

Vienna
Austria

Gabriela Kornek

Medical University of Vienna - Vienna General Hospital

Vienna
Austria

Bernhard Parschalk

Medical University of Vienna - Vienna General Hospital ( email )

Vienna
Austria

Maximilian Schnetzinger

Medical University of Vienna - Vienna General Hospital ( email )

Vienna
Austria

Robert Strassl

Medical University of Vienna - Vienna General Hospital ( email )

Vienna
Austria

Rebeka Savic

Medical University of Vienna - Vienna General Hospital ( email )

Vienna
Austria

Andrea Foit

Medical University of Vienna - Vienna General Hospital

Vienna
Austria

Helene Resch

Medical University of Vienna - Vienna General Hospital

Vienna
Austria

Florian Thalhammer

Medical University of Vienna - Vienna General Hospital ( email )

Vienna
Austria