Relative effectiveness of monovalent and bivalent mRNA boosters in preventing severe COVID-19 due to omicron BA.5 infection up to 4 months post-administration in people aged 60 years or older in Italy: a retrospective matched cohort study.

Autor:	Mateo-Urdiales A; Department of Infectious Diseases, Istituto Superiore di Sanità, Rome, Italy. Electronic address: alberto.mateourdiales@iss.it., Sacco C; Department of Infectious Diseases, Istituto Superiore di Sanità, Rome, Italy; European Programme on Intervention Epidemiology Training (EPIET), European Centre for Disease Prevention and Control, Stockholm, Sweden., Fotakis EA; Department of Infectious Diseases, Istituto Superiore di Sanità, Rome, Italy; European Programme on Intervention Epidemiology Training (EPIET), European Centre for Disease Prevention and Control, Stockholm, Sweden., Del Manso M; Department of Infectious Diseases, Istituto Superiore di Sanità, Rome, Italy., Bella A; Department of Infectious Diseases, Istituto Superiore di Sanità, Rome, Italy., Riccardo F; Department of Infectious Diseases, Istituto Superiore di Sanità, Rome, Italy., Bressi M; Department of Infectious Diseases, Istituto Superiore di Sanità, Rome, Italy., Rota MC; Department of Infectious Diseases, Istituto Superiore di Sanità, Rome, Italy., Petrone D; Department of Infectious Diseases, Istituto Superiore di Sanità, Rome, Italy; Department of Statistics, Sapienza University, Rome, Italy., Siddu A; General Directorate of Prevention, Ministry of Health, Rome, Italy., Fedele G; Department of Infectious Diseases, Istituto Superiore di Sanità, Rome, Italy., Stefanelli P; Department of Infectious Diseases, Istituto Superiore di Sanità, Rome, Italy., Palamara AT; Department of Infectious Diseases, Istituto Superiore di Sanità, Rome, Italy., Brusaferro S; Istituto Superiore di Sanità, Rome, Italy., Rezza G; General Directorate of Prevention, Ministry of Health, Rome, Italy., Pezzotti P; Department of Infectious Diseases, Istituto Superiore di Sanità, Rome, Italy., Fabiani M; Department of Infectious Diseases, Istituto Superiore di Sanità, Rome, Italy.
Jazyk:	angličtina
Zdroj:	The Lancet. Infectious diseases [Lancet Infect Dis] 2023 Dec; Vol. 23 (12), pp. 1349-1359. Date of Electronic Publication: 2023 Jul 18.
DOI:	10.1016/S1473-3099(23)00374-2
Abstrakt:	Background: Limited evidence is available on the additional protection conferred by second mRNA vaccine boosters against severe COVID-19 caused by omicron BA.5 infection, and whether the adapted bivalent boosters provide additional protection compared with the monovalent ones. In this study, we aimed to estimate the relative effectiveness of a second booster with monovalent or bivalent mRNA vaccines against severe COVID-19 in Italy. Methods: Linking data from the Italian vaccination registry and the SARS-CoV-2 surveillance system, between Sept 12, 2022, and Jan 7, 2023, we matched 1:1 each person aged 60 years or older receiving a second booster with a person who had received the first booster only at least 120 days earlier. We used hazard ratios, estimated through Cox proportional hazard models, to compare the hazard of severe COVID-19 between the first booster group and each type of second booster (monovalent mRNA vaccine targeting the original strain of SARS-CoV-2, bivalent mRNA vaccine targeting the original strain plus omicron BA.1 [bivalent original/BA.1], and bivalent mRNA vaccine targeting the original strain plus omicron BA.4 and BA.5 [bivalent original/BA.4-5]). Relative vaccine effectiveness (rVE) was calculated as (1-hazard ratio) × 100. Findings: We analysed a total of 2 129 559 matched pairs. The estimated rVE against severe COVID-19 with the bivalent original/BA.4-5 booster was 50·6% (95% CI 46·0-54·8) in the overall time interval 14-118 days post-administration. Overall, rVE was 49·3% (43·6-54·4) for the bivalent original/BA.1 booster and 26·9% (11·8-39·3) for the monovalent booster. For the bivalent original/BA.4-5 booster, we did not observe relevant differences in rVE between the 60-79-year age group (overall, 53·6%; 46·8-59·5) and those aged 80 years or older (overall, 48·3%; 41·9-54·0). Interpretation: These findings suggest that a second booster with mRNA vaccines provides additional protection against severe COVID-19 due to omicron BA.5 (the predominant circulating subvariant in Italy during the study period) in people aged 60 years or older. Although rVE decreased over time, a second booster with the original/BA.4-5 mRNA vaccine, currently the most used in Italy, was found to be still providing protection 4 months post-administration. Funding: NextGenerationEU-MUR-PNRR Extended Partnership initiative on Emerging Infectious Diseases (project number PE00000007, INF-ACT). Translation: For the Italian translation of the abstract see Supplementary Materials section. Competing Interests: Declaration of interests We declare no competing interests. (Copyright © 2023 Elsevier Ltd. All rights reserved.)
Databáze:	MEDLINE
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