Omicron (BA.1) SARS-CoV-2 variant is associated with reduced risk of hospitalization and length of stay compared with Delta (B.1.617.2)
Omicron (BA.1) SARS-CoV-2 variant is associated with reduced risk of hospitalization and length of stay compared with Delta (B.1.617.2)
Abstract IntroductionEarly reports showed that Omicron (BA.1) SARS-CoV-2 could be less severe. However, the magnitude of risk reduction of hospitalization and mortality of Omicron (BA.1) infections compared with Delta (B.1.617.2) is not yet clear. This study compares the risk of severe disease among patients infected with the Omicron (BA.1) variant with patients infected with Delta (B.1.617.2) variant in Portugal. MethodsWe conducted a cohort study in individuals diagnosed with SARS-CoV-2 infection between 1st and 29th December 2021. Cases were individuals with a positive PCR test notified to the national surveillance system. SARS-CoV-2 variants were classified first by whole genomic sequencing (WGS) and, if this information was unavailable, by detecting the S gene target failure. We considered a hospitalization for all the patients admitted within the 14 days after the SARS-CoV-2 infection; after that period, they were censored.The comparison of the risk of hospitalization between Omicron (BA.1) and Delta (B.1.617.2) VOC was estimated using a Cox proportional hazards model. The mean length of stay was compared using linear regression, and the risk of death between Omicron and Delta patients was estimated with a penalized logistic regression. All models were adjusted for sex, age, previous infection, and vaccination status. ResultsWe included 15 978 participants aged 16 or more years old, 9 397 infected by Delta (B.1.617.2) and 6 581 infected with Omicron (BA.1). Within the Delta (B.1.617.2) group, 148 (1.6%) were hospitalized, and 16 (0.2%) were with the Omicron (BA.1). A total of 26 deaths were reported, all in participants with Delta (B.1.617.2) infection. Adjusted HR for hospitalization for the Omicron (BA.1) variant compared with Delta (B.1.617.2) was 0.25 (95%CI 0.15 to 0.43). The length of stay in hospital for Omicron (BA.1) patients was significantly shorter than for Delta (confounding-adjusted difference -4.0 days (95%CI -7.2 to -0.8). The odds of death were 0.14 (95% CI 0.0011 to 1.12), representing a reduction in the risk of death of 86% when infected with Omicron (BA.1) compared with Delta (B.1.617.2). ConclusionOmicron (BA.1) was associated with a 75% risk reduction of hospitalization compared with Delta (B.1.617.2) and reduced length of hospital stay.
Moreno Joana、Peralta-Santos Andr¨|、Borges V¨ator、Almeida Jos¨| Pedro、Ferreira Rita、Isidro Joana、Fernandes Eugenia、Pinto Miguel、Freire Samanta、Grilo Teresa、Borges Cl¨￠udia Medeiros、Kislaya Irina、Ricoca Vasco、Duarte S¨alvia、Matias Ana、Ferreira Bibiana I.、Moutinho Vera、Rodrigues Eduardo Freire、Nunes Baltazar、Rodrigues Ana Paula、Leite Andreia、Casaca Pedro、Vieira Lu¨as、Pelerito Ana、Leite Pedro Pinto、Sousa Carlos、Menezes Lu¨as、Gomes Jo?o Paulo
Dire??o de Servi?os de Informa??o e An¨￠liseDire??o de Servi?os de Informa??o e An¨￠lise||NOVA National School of Public Health, Public Health Research Centre, Universidade NOVA de Lisboa||Comprehensive Health Research Centre (CHRC), Universidade NOVA de LisboaBioinformatics Unit, Department of Infectious Diseases, National Institute of Health Doutor Ricardo Jorge (INSA)UnilabsBioinformatics Unit, Department of Infectious Diseases, National Institute of Health Doutor Ricardo Jorge (INSA)Bioinformatics Unit, Department of Infectious Diseases, National Institute of Health Doutor Ricardo Jorge (INSA)Dire??o de Servi?os de Informa??o e An¨￠liseBioinformatics Unit, Department of Infectious Diseases, National Institute of Health Doutor Ricardo Jorge (INSA)Portuguese Red Cross LaboratoryPortuguese Red Cross LaboratoryAdministra??o Central do Sistema de Sa¨2de, IP (ACSS, Health System Central Administration)Departamento de Epidemiologia, Instituto Nacional de Sa¨2de Doutor Ricardo JorgeDire??o de Servi?os de Informa??o e An¨￠lise||NOVA National School of Public Health, Public Health Research Centre, Universidade NOVA de Lisboa||Comprehensive Health Research Centre (CHRC), Universidade NOVA de LisboaInnovation and Technology Unit, Department of Human Genetics, National Institute of Health Doutor Ricardo Jorge (INSA)Faculty of Medicine and Biomedical Sciences (FMCB), Campus de Gambelas, University of AlgarveAlgarve Biomedical Center Research Institute (ABC-RI)Servi?os Partilhados do Minist¨|rio da Sa¨2de, EPE (SPMS, Shared Services for Ministry of Health)Dire??o de Servi?os de Informa??o e An¨￠liseNOVA National School of Public Health, Public Health Research Centre, Universidade NOVA de Lisboa||Comprehensive Health Research Centre (CHRC), Universidade NOVA de Lisboa||Departamento de Epidemiologia, Instituto Nacional de Sa¨2de Doutor Ricardo JorgeDepartamento de Epidemiologia, Instituto Nacional de Sa¨2de Doutor Ricardo JorgeNOVA National School of Public Health, Public Health Research Centre, Universidade NOVA de Lisboa||Comprehensive Health Research Centre (CHRC), Universidade NOVA de LisboaDire??o de Servi?os de Informa??o e An¨￠liseInnovation and Technology Unit, Department of Human Genetics, National Institute of Health Doutor Ricardo Jorge (INSA)Portuguese Red Cross LaboratoryDire??o de Servi?os de Informa??o e An¨￠liseUnilabsUnilabsBioinformatics Unit, Department of Infectious Diseases, National Institute of Health Doutor Ricardo Jorge (INSA)
医学研究方法医药卫生理论
COVID-19SARS-CoV-2hospitalizationOmicronBA.1DeltaB.1.617.2severity
Moreno Joana,Peralta-Santos Andr¨|,Borges V¨ator,Almeida Jos¨| Pedro,Ferreira Rita,Isidro Joana,Fernandes Eugenia,Pinto Miguel,Freire Samanta,Grilo Teresa,Borges Cl¨￠udia Medeiros,Kislaya Irina,Ricoca Vasco,Duarte S¨alvia,Matias Ana,Ferreira Bibiana I.,Moutinho Vera,Rodrigues Eduardo Freire,Nunes Baltazar,Rodrigues Ana Paula,Leite Andreia,Casaca Pedro,Vieira Lu¨as,Pelerito Ana,Leite Pedro Pinto,Sousa Carlos,Menezes Lu¨as,Gomes Jo?o Paulo.Omicron (BA.1) SARS-CoV-2 variant is associated with reduced risk of hospitalization and length of stay compared with Delta (B.1.617.2)[EB/OL].(2025-03-28)[2025-05-11].https://www.medrxiv.org/content/10.1101/2022.01.20.22269406.点此复制
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