The Effectiveness of COVID-19 Vaccines During the Pre-Omicron and Omicron Periods: A Retrospective Test-Negative Case–Control Study
Background: The aim of this study was to estimate the effectiveness of original and bivalent COVID-19 vaccines in reducing COVID-19-associated hospitalizations among the adult population of Turin, Italy. Methods: We conducted a retrospective, test-negative, case–control study of 5768 adults aged ≥50...
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2024-10-01
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| Online Access: | https://www.mdpi.com/2076-393X/12/11/1245 |
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| author | Romeo Brambilla Renata Gili Federica Vigna Taglianti Jacopo Lenzi Matteo Riccò Roberto Burioni Mariaelisabetta Scarvaglieri Rachele Rocco Vittorina Buttafuoco Rosa Maria Teresa Antonia Cristaudo Davide Gori |
| author_facet | Romeo Brambilla Renata Gili Federica Vigna Taglianti Jacopo Lenzi Matteo Riccò Roberto Burioni Mariaelisabetta Scarvaglieri Rachele Rocco Vittorina Buttafuoco Rosa Maria Teresa Antonia Cristaudo Davide Gori |
| author_sort | Romeo Brambilla |
| collection | DOAJ |
| description | Background: The aim of this study was to estimate the effectiveness of original and bivalent COVID-19 vaccines in reducing COVID-19-associated hospitalizations among the adult population of Turin, Italy. Methods: We conducted a retrospective, test-negative, case–control study of 5768 adults aged ≥50 years who had symptoms that were consistent with COVID-19-like illness and were admitted to the hospitals of the Turin Health Unit network from 1 January 2021 to 31 January 2023. We evaluated the effectiveness of the vaccines that at the time of the study were authorized in the European Union (original/bivalent BNT162b2; original mRNA-1273; ChAdOx1-S; Ad26.COV2.S) by comparing the odds of a positive test for SARS-CoV-2 in vaccinated patients with the odds of a positive test in unvaccinated patients. The association between vaccination status, hospitalization, ICU admission and positive SARS-CoV-2 test was estimated by building multivariate adjusted logistic regression models. Results: During the predominance of the pre-Omicron variants, the vaccine effectiveness of two and three doses received in the last 120 days against COVID-19-associated hospitalizations was 93.6% (95% CI: 90.1 to 95.9) and 97.1% (95% CI: 90.8 to 99.1), respectively. During the predominance of the Omicron variant, the vaccine effectiveness of two and three doses was 26.6% (95% CI: −0.6 to 46.5) and 75.2% (95% CI: 68.1 to 80.7), respectively, and it rose to 88% (95% CI: 78.2 to 93.3) for four or five doses of the bivalent vaccine. Conclusions: Our study confirms that the COVID-19 vaccines protect adult patients from hospitalizations, including the subgroup ≥80 years, also during the period of the Omicron variant’s predominance. |
| format | Article |
| id | doaj-art-dab1c680ba9349f099d5d4b018e80e06 |
| institution | Kabale University |
| issn | 2076-393X |
| language | English |
| publishDate | 2024-10-01 |
| publisher | MDPI AG |
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| series | Vaccines |
| spelling | doaj-art-dab1c680ba9349f099d5d4b018e80e062024-11-26T18:24:35ZengMDPI AGVaccines2076-393X2024-10-011211124510.3390/vaccines12111245The Effectiveness of COVID-19 Vaccines During the Pre-Omicron and Omicron Periods: A Retrospective Test-Negative Case–Control StudyRomeo Brambilla0Renata Gili1Federica Vigna Taglianti2Jacopo Lenzi3Matteo Riccò4Roberto Burioni5Mariaelisabetta Scarvaglieri6Rachele Rocco7Vittorina Buttafuoco8Rosa Maria Teresa Antonia Cristaudo9Davide Gori10Local Health Unit of Torino, Department of Prevention, Via Silvio Pellico 19, 10125 Turin, ItalyLocal Health Unit of Torino, Department of Prevention, Via Silvio Pellico 19, 10125 Turin, ItalyDepartment of Translational Medicine, University of Eastern Piedmont, Via Solaroli 17, 28100 Novara, ItalyDepartment of Biomedical and Neuromotor Sciences (DIBINEM), University of Bologna, 40126 Bologna, ItalyAUSL–IRCCS di Reggio Emilia, Servizio di Prevenzione e Sicurezza Negli Ambienti di Lavoro (SPSAL), Local Health Unit of Reggio Emilia, 42122 Reggio Emilia, ItalyDepartment of Microbiology and Virology, Università Vita Salute San Raffaele Medical School, Via Olgettina 58, 20132 Milan, ItalyLocal Health Unit of Torino, Department of Prevention, Via Silvio Pellico 19, 10125 Turin, ItalyLocal Health Unit of Torino, Department of Prevention, Via Silvio Pellico 19, 10125 Turin, ItalyLocal Health Unit of Torino, Department of Prevention, Via Silvio Pellico 19, 10125 Turin, ItalyLocal Health Unit of Torino, Department of Prevention, Via Silvio Pellico 19, 10125 Turin, ItalyDepartment of Biomedical and Neuromotor Sciences (DIBINEM), University of Bologna, 40126 Bologna, ItalyBackground: The aim of this study was to estimate the effectiveness of original and bivalent COVID-19 vaccines in reducing COVID-19-associated hospitalizations among the adult population of Turin, Italy. Methods: We conducted a retrospective, test-negative, case–control study of 5768 adults aged ≥50 years who had symptoms that were consistent with COVID-19-like illness and were admitted to the hospitals of the Turin Health Unit network from 1 January 2021 to 31 January 2023. We evaluated the effectiveness of the vaccines that at the time of the study were authorized in the European Union (original/bivalent BNT162b2; original mRNA-1273; ChAdOx1-S; Ad26.COV2.S) by comparing the odds of a positive test for SARS-CoV-2 in vaccinated patients with the odds of a positive test in unvaccinated patients. The association between vaccination status, hospitalization, ICU admission and positive SARS-CoV-2 test was estimated by building multivariate adjusted logistic regression models. Results: During the predominance of the pre-Omicron variants, the vaccine effectiveness of two and three doses received in the last 120 days against COVID-19-associated hospitalizations was 93.6% (95% CI: 90.1 to 95.9) and 97.1% (95% CI: 90.8 to 99.1), respectively. During the predominance of the Omicron variant, the vaccine effectiveness of two and three doses was 26.6% (95% CI: −0.6 to 46.5) and 75.2% (95% CI: 68.1 to 80.7), respectively, and it rose to 88% (95% CI: 78.2 to 93.3) for four or five doses of the bivalent vaccine. Conclusions: Our study confirms that the COVID-19 vaccines protect adult patients from hospitalizations, including the subgroup ≥80 years, also during the period of the Omicron variant’s predominance.https://www.mdpi.com/2076-393X/12/11/1245vaccinationCOVID-19effectivenesstest-negative designboosterbivalent vaccine |
| spellingShingle | Romeo Brambilla Renata Gili Federica Vigna Taglianti Jacopo Lenzi Matteo Riccò Roberto Burioni Mariaelisabetta Scarvaglieri Rachele Rocco Vittorina Buttafuoco Rosa Maria Teresa Antonia Cristaudo Davide Gori The Effectiveness of COVID-19 Vaccines During the Pre-Omicron and Omicron Periods: A Retrospective Test-Negative Case–Control Study Vaccines vaccination COVID-19 effectiveness test-negative design booster bivalent vaccine |
| title | The Effectiveness of COVID-19 Vaccines During the Pre-Omicron and Omicron Periods: A Retrospective Test-Negative Case–Control Study |
| title_full | The Effectiveness of COVID-19 Vaccines During the Pre-Omicron and Omicron Periods: A Retrospective Test-Negative Case–Control Study |
| title_fullStr | The Effectiveness of COVID-19 Vaccines During the Pre-Omicron and Omicron Periods: A Retrospective Test-Negative Case–Control Study |
| title_full_unstemmed | The Effectiveness of COVID-19 Vaccines During the Pre-Omicron and Omicron Periods: A Retrospective Test-Negative Case–Control Study |
| title_short | The Effectiveness of COVID-19 Vaccines During the Pre-Omicron and Omicron Periods: A Retrospective Test-Negative Case–Control Study |
| title_sort | effectiveness of covid 19 vaccines during the pre omicron and omicron periods a retrospective test negative case control study |
| topic | vaccination COVID-19 effectiveness test-negative design booster bivalent vaccine |
| url | https://www.mdpi.com/2076-393X/12/11/1245 |
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