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. 2023 Aug;28(32):2300397.
doi: 10.2807/1560-7917.ES.2023.28.32.2300397.

Relative effectiveness of bivalent Original/Omicron BA.4-5 mRNA vaccine in preventing severe COVID-19 in persons 60 years and above during SARS-CoV-2 Omicron XBB.1.5 and other XBB sublineages circulation, Italy, April to June 2023

Massimo Fabiani  1 , Alberto Mateo-Urdiales  1 , Chiara Sacco  1 , Maria Cristina Rota  1 , Emmanouil Alexandros Fotakis  2   1 , Daniele Petrone  1 , Martina Del Manso  1 , Andrea Siddu  3 , Paola Stefanelli  1 , Antonino Bella  1 , Flavia Riccardo  1 , Giovanni Rezza  3 , Anna Teresa Palamara  1 , 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

Relative effectiveness of bivalent Original/Omicron BA.4-5 mRNA vaccine in preventing severe COVID-19 in persons 60 years and above during SARS-CoV-2 Omicron XBB.1.5 and other XBB sublineages circulation, Italy, April to June 2023

Massimo Fabiani et al. Euro Surveill. 2023 Aug.

Abstract

During predominant circulation of SARS-CoV-2 Omicron XBB.1.5 and other XBB sublineages (April-June 2023), we found that a second or third booster of Comirnaty bivalent Original/Omicron BA.4-5 mRNA vaccine, versus a first booster received at least 120 days earlier, was effective in preventing severe COVID-19 for more than 6 months post-administration in persons 60 years and above. In view of autumn 2023 vaccination campaigns, use of bivalent Original/Omicron BA.4-5 mRNA vaccines might be warranted until monovalent COVID-19 vaccines targeting Omicron XBB.1 sublineages become available.

Keywords: COVID-19; Italy; Omicron XBB sublineages; bivalent mRNA vaccines; effectiveness.

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Conflict of interest statement

Conflict of interests: None declared.

Figures

Figure 1
Figure 1
Percentage distribution of the circulating SARS-CoV-2 variants by calendar week, Italy, 3 April–4 June 2023 (n = 4,032)
Figure 2
Figure 2
Selection of the study participants, Italy, 3 April–4 June 2023 (n = 15,665,359)
See this image and copyright information in PMC

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