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, Alberto Mateo‐Urdiales, Chiara Sacco, Maria Cristina Rota, Emmanouil Alexandros Fotakis, Daniele Petrone, Martina Del Manso, Andrea Siddu, Paola Stefanelli, Antonino Bella, Flavia Riccardo, Giovanni Rezza, Anna Teresa Palamara, Silvio Brusaferro, Patrizio Pezzotti, on behalf of the Italian Integrated Surveillance of COVID-19 study group and of the Italian COVID-19 Vaccines Registry group
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.