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SHR Neuro Cancer Cardio Lipid Metab Microb

Chalupka, A; Richter, L; Chakeri, A; El-Khatib, Z; Theiler-Schwetz, V; Trummer, C; Krause, R; Willeit, P; Benka, B; Ioannidis, JPA; Pilz, S.
Effectiveness of a fourth SARS-CoV-2 vaccine dose in previously infected individuals from Austria.
Eur J Clin Invest. 2024; 54(3):e14136 Doi: 10.1111/eci.14136 [OPEN ACCESS]
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Leading authors Med Uni Graz

Pilz Stefan

Co-authors Med Uni Graz

Krause Robert

Theiler-Schwetz Verena

Trummer Christian

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Abstract:

INTRODUCTION: Evidence is limited on the effectiveness of a fourth vaccine dose against coronavirus disease 2019 (COVID-19) in populations with prior severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections. We estimated the risk of COVID-19 deaths and SARS-CoV-2 infections according to vaccination status in previously infected individuals in Austria. METHODS: This is a nationwide retrospective observational study. We calculated age and gender adjusted Cox proportional hazard ratios (HRs) of COVID-19 deaths (primary outcome) and SARS-CoV-2 infections (secondary outcome) from 1 November to 31 December 2022, primarily comparing individuals with four versus three vaccine doses. Relative vaccine effectiveness (rVE) was calculated as (1-HR) X 100. RESULTS: Among 3,986,312 previously infected individuals, 281,291 (7,1%) had four and 1,545,242 (38.8%) had three vaccinations at baseline. We recorded 69 COVID-19 deaths and 89,056 SARS-CoV-2 infections. rVE for four versus three vaccine doses was -24% (95% CI: -120 to 30) against COVID-19 deaths, and 17% (95% CI: 14-19) against SARS-CoV-2 infections. This latter effect rapidly diminished over time and infection risk with four vaccinations was higher compared to less vaccinated individuals during extended follow-up until June 2023. Adjusted HR (95% CI) for all-cause mortality for four versus three vaccinations was 0.79 (0.74-0.85). DISCUSSION: In previously infected individuals, a fourth vaccination was not associated with COVID-19 death risk, but with transiently reduced risk of SARS-CoV-2 infections and reversal of this effect in longer follow-up. All-cause mortality data suggest healthy vaccinee bias.

Find related publications in this database (using NLM MeSH Indexing)

Humans - administration & dosage

COVID-19 Vaccines - administration & dosage

COVID-19 - epidemiology, prevention & control

Austria - epidemiology

SARS-CoV-2 - administration & dosage

Vaccination - administration & dosage

Find related publications in this database (Keywords)

booster

COVID-19

mortality

national

SARS-CoV-2

vaccine

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