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. 2023 Feb;28(8):2300105.
doi: 10.2807/1560-7917.ES.2023.28.8.2300105.

Protection against severe COVID-19 after second booster dose of adapted bivalent (original/Omicron BA.4-5) mRNA vaccine in persons ≥ 60 years, by time since infection, Italy, 12 September to 11 December 2022

Massimo Fabiani  1 , Alberto Mateo-Urdiales  1 , Chiara Sacco  1   2 , Emmanouil Alexandros Fotakis  1   2 , Maria Cristina Rota  1 , Daniele Petrone  1 , Marco Bressi  1 , Martina Del Manso  1 , Andrea Siddu  3 , Giorgio Fedele  1 , Paola Stefanelli  1 , Antonino Bella  1 , Flavia Riccardo  1 , Anna Teresa Palamara  1 , Giovanni Rezza  3 , Silvio Brusaferro  4 , Patrizio Pezzotti  1 ; Italian Integrated Surveillance of COVID-19 study group and of the Italian COVID-19 Vaccines Registry group  5
Affiliations

Protection against severe COVID-19 after second booster dose of adapted bivalent (original/Omicron BA.4-5) mRNA vaccine in persons ≥ 60 years, by time since infection, Italy, 12 September to 11 December 2022

Massimo Fabiani et al. Euro Surveill. 2023 Feb.

Abstract

Effectiveness against severe COVID-19 of a second booster dose of the bivalent (original/BA.4-5) mRNA vaccine 7-90 days post-administration, relative to a first booster dose of an mRNA vaccine received ≥ 120 days earlier, was ca 60% both in persons ≥ 60 years never infected and in those infected > 6 months before. Relative effectiveness in those infected 4-6 months earlier indicated no significant additional protection (10%; 95% CI: -44 to 44). A second booster vaccination 6 months after the latest infection may be warranted.

Keywords: COVID-19; Italy; SARS-CoV-2; bivalent mRNA vaccines; effectiveness; elderly population.

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Figures

Figure 1
Figure 1
Selection of the COVID-19 vaccine effectiveness study participants, Italy, 14 September 2021–11 December 2022 (n = 15,751,355)
Figure 2
Figure 2
Per cent distribution of SARS-CoV-2 variants associated with prior infections in the study participants, Italy, 21 February 2020–12 August 2022 (n = 2,520,283)
See this image and copyright information in PMC

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