Eurosurv. Protection against severe COVID-19 after second booster dose of adapted bivalent (original/Omicron BA.4-5) mRNA vaccine in persons ≥ 60 year

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

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.


https://www.eurosurveillance.org/content/10.2807/1560-7917.ES.2023.28.8.2300105#html_fulltext