Reduction of the risk of severe COVID-19 due to Omicron compared to Delta variant in Italy (November 2021 – February 2022)
Objectives: During 2022, Omicron became the dominant SARS-CoV-2 variant in Europe. This study aims to assess the impact of such variant on severe disease from SARS-CoV-2 compared with the Delta variant in Italy. Methods: Using surveillance data, we assessed the risk of developing severe COVID-19 wit...
| Main Authors: | , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
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Elsevier
2023-04-01
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| Series: | International Journal of Infectious Diseases |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S1201971223000279 |
| _version_ | 1797868320102285312 |
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| author | Daniele Petrone Alberto Mateo-Urdiales Chiara Sacco Flavia Riccardo Antonino Bella Luigina Ambrosio Alessandra Lo Presti Angela Di Martino Emiliano Ceccarelli Martina Del Manso Massimo Fabiani Paola Stefanelli Patrizio Pezzotti AnnaTeresa Palamara |
| author_facet | Daniele Petrone Alberto Mateo-Urdiales Chiara Sacco Flavia Riccardo Antonino Bella Luigina Ambrosio Alessandra Lo Presti Angela Di Martino Emiliano Ceccarelli Martina Del Manso Massimo Fabiani Paola Stefanelli Patrizio Pezzotti AnnaTeresa Palamara |
| author_sort | Daniele Petrone |
| collection | DOAJ |
| description | Objectives: During 2022, Omicron became the dominant SARS-CoV-2 variant in Europe. This study aims to assess the impact of such variant on severe disease from SARS-CoV-2 compared with the Delta variant in Italy. Methods: Using surveillance data, we assessed the risk of developing severe COVID-19 with Omicron infection compared with Delta in individuals aged ≥12 years using a multilevel negative binomial model adjusting for sex, age, vaccination status, occupation, previous infection, weekly incidence, and geographical area. We also analyzed the interaction between the sequenced variant, age, and vaccination status. Results: We included 21,645 cases of SARS-CoV-2 infection where genome sequencing found Delta (10,728) or Omicron (10,917), diagnosed from November 15, 2021 to February 01, 2022. Overall, 3,021 cases developed severe COVID-19. We found that Omicron cases had a reduced risk of severe COVID-19 compared with Delta cases (incidence rate ratio [IRR] = 0.77; 95% confidence interval [CI]: 0.70-0.86). The largest difference was observed in cases aged 40-59 (IRR = 0.66; 95% CI: 0.55-0.79), while no protective effect was found in those aged 12-39 (IRR = 1.03; 95% CI: 0.79-1.33). Vaccination was associated with a lower risk of developing severe COVID-19 in both variants. Conclusion: The Omicron variant is associated with a lower risk of severe COVID-19 compared to infection with the Delta variant, but the degree of protection varies with age. |
| first_indexed | 2024-04-09T23:55:09Z |
| format | Article |
| id | doaj.art-d0f7860fd92645729a75fff3cbb94615 |
| institution | Directory Open Access Journal |
| issn | 1201-9712 |
| language | English |
| last_indexed | 2024-04-09T23:55:09Z |
| publishDate | 2023-04-01 |
| publisher | Elsevier |
| record_format | Article |
| series | International Journal of Infectious Diseases |
| spelling | doaj.art-d0f7860fd92645729a75fff3cbb946152023-03-17T04:32:44ZengElsevierInternational Journal of Infectious Diseases1201-97122023-04-01129135141Reduction of the risk of severe COVID-19 due to Omicron compared to Delta variant in Italy (November 2021 – February 2022)Daniele Petrone0Alberto Mateo-Urdiales1Chiara Sacco2Flavia Riccardo3Antonino Bella4Luigina Ambrosio5Alessandra Lo Presti6Angela Di Martino7Emiliano Ceccarelli8Martina Del Manso9Massimo Fabiani10Paola Stefanelli11Patrizio Pezzotti12AnnaTeresa Palamara13Department of Infectious Diseases, Istituto Superiore di Sanità, Rome, Italy; Department of Statistics, Sapienza University of Rome, Rome, ItalyDepartment of Infectious Diseases, Istituto Superiore di Sanità, Rome, Italy; Corresponding author:Department of Infectious Diseases, Istituto Superiore di Sanità, Rome, ItalyDepartment of Infectious Diseases, Istituto Superiore di Sanità, Rome, ItalyDepartment of Infectious Diseases, Istituto Superiore di Sanità, Rome, ItalyDepartment of Infectious Diseases, Istituto Superiore di Sanità, Rome, ItalyDepartment of Infectious Diseases, Istituto Superiore di Sanità, Rome, ItalyDepartment of Infectious Diseases, Istituto Superiore di Sanità, Rome, ItalyDepartment of Infectious Diseases, Istituto Superiore di Sanità, Rome, ItalyDepartment of Infectious Diseases, Istituto Superiore di Sanità, Rome, ItalyDepartment of Infectious Diseases, Istituto Superiore di Sanità, Rome, ItalyDepartment of Infectious Diseases, Istituto Superiore di Sanità, Rome, ItalyDepartment of Infectious Diseases, Istituto Superiore di Sanità, Rome, ItalyDepartment of Infectious Diseases, Istituto Superiore di Sanità, Rome, Italy; Corresponding author:Objectives: During 2022, Omicron became the dominant SARS-CoV-2 variant in Europe. This study aims to assess the impact of such variant on severe disease from SARS-CoV-2 compared with the Delta variant in Italy. Methods: Using surveillance data, we assessed the risk of developing severe COVID-19 with Omicron infection compared with Delta in individuals aged ≥12 years using a multilevel negative binomial model adjusting for sex, age, vaccination status, occupation, previous infection, weekly incidence, and geographical area. We also analyzed the interaction between the sequenced variant, age, and vaccination status. Results: We included 21,645 cases of SARS-CoV-2 infection where genome sequencing found Delta (10,728) or Omicron (10,917), diagnosed from November 15, 2021 to February 01, 2022. Overall, 3,021 cases developed severe COVID-19. We found that Omicron cases had a reduced risk of severe COVID-19 compared with Delta cases (incidence rate ratio [IRR] = 0.77; 95% confidence interval [CI]: 0.70-0.86). The largest difference was observed in cases aged 40-59 (IRR = 0.66; 95% CI: 0.55-0.79), while no protective effect was found in those aged 12-39 (IRR = 1.03; 95% CI: 0.79-1.33). Vaccination was associated with a lower risk of developing severe COVID-19 in both variants. Conclusion: The Omicron variant is associated with a lower risk of severe COVID-19 compared to infection with the Delta variant, but the degree of protection varies with age.http://www.sciencedirect.com/science/article/pii/S1201971223000279SARS-CoV-2Delta variantOmicron variantCOVID-19HospitalizationDeath |
| spellingShingle | Daniele Petrone Alberto Mateo-Urdiales Chiara Sacco Flavia Riccardo Antonino Bella Luigina Ambrosio Alessandra Lo Presti Angela Di Martino Emiliano Ceccarelli Martina Del Manso Massimo Fabiani Paola Stefanelli Patrizio Pezzotti AnnaTeresa Palamara Reduction of the risk of severe COVID-19 due to Omicron compared to Delta variant in Italy (November 2021 – February 2022) International Journal of Infectious Diseases SARS-CoV-2 Delta variant Omicron variant COVID-19 Hospitalization Death |
| title | Reduction of the risk of severe COVID-19 due to Omicron compared to Delta variant in Italy (November 2021 – February 2022) |
| title_full | Reduction of the risk of severe COVID-19 due to Omicron compared to Delta variant in Italy (November 2021 – February 2022) |
| title_fullStr | Reduction of the risk of severe COVID-19 due to Omicron compared to Delta variant in Italy (November 2021 – February 2022) |
| title_full_unstemmed | Reduction of the risk of severe COVID-19 due to Omicron compared to Delta variant in Italy (November 2021 – February 2022) |
| title_short | Reduction of the risk of severe COVID-19 due to Omicron compared to Delta variant in Italy (November 2021 – February 2022) |
| title_sort | reduction of the risk of severe covid 19 due to omicron compared to delta variant in italy november 2021 february 2022 |
| topic | SARS-CoV-2 Delta variant Omicron variant COVID-19 Hospitalization Death |
| url | http://www.sciencedirect.com/science/article/pii/S1201971223000279 |
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