Transmissibility, hospitalization, and intensive care admissions due to omicron compared to delta variants of SARS-CoV-2 in Catalonia

We aim to compare the severity of infections between omicron and delta variants in 609,352 SARS-CoV-2 positive cases using local hospitalization, vaccination, and variants data from the Catalan Health Care System (which covers around 7. 8 million people). We performed a substitution model to establi...

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Autores: Català, Martí|||0000-0003-3308-9905, Coma, Ermengol|||0000-0001-8000-3321, Alonso Muñoz, Sergio|||0000-0002-3989-8757, Andrés, Cristina|||0000-0002-3200-0895, Blanco Guillermo, Ignacio|||0000-0002-7414-7481, Antón Pagarolas, Andrés, 1976-|||0000-0002-1476-0815, Bordoy, Antoni E.|||0000-0002-1165-542X, Cardona, Pere-Joan|||0000-0001-5623-7873, Fina, Francesc, Martró, Elisa|||0000-0002-2867-6649, Medina, Manuel, Mora, Núria, Saludes, Verónica|||0000-0003-2139-3360, Prats, Clara|||0000-0002-1398-7559, Prieto-Alhambra, Daniel|||0000-0002-3950-6346, Alvarez-Lacalle, Enrique|||0000-0001-6824-6857
Tipo de recurso: artículo
Fecha de publicación:2022
País:España
Institución:Universitat Autònoma de Barcelona
Repositorio:Dipòsit Digital de Documents de la UAB
Idioma:inglés
OAI Identifier:oai:ddd.uab.cat:266427
Acceso en línea:https://ddd.uab.cat/record/266427
https://dx.doi.org/urn:doi:10.3389/fpubh.2022.961030
Access Level:acceso abierto
Palabra clave:COVID-19
Severity
Ecological study
Cohorts
Substitution model
Severity and vaccination status
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repository_id_str
spelling Transmissibility, hospitalization, and intensive care admissions due to omicron compared to delta variants of SARS-CoV-2 in CataloniaA cohort study and ecological analysisCatalà, Martí|||0000-0003-3308-9905Coma, Ermengol|||0000-0001-8000-3321Alonso Muñoz, Sergio|||0000-0002-3989-8757Andrés, Cristina|||0000-0002-3200-0895Blanco Guillermo, Ignacio|||0000-0002-7414-7481Antón Pagarolas, Andrés, 1976-|||0000-0002-1476-0815Bordoy, Antoni E.|||0000-0002-1165-542XCardona, Pere-Joan|||0000-0001-5623-7873Fina, FrancescMartró, Elisa|||0000-0002-2867-6649Medina, ManuelMora, NúriaSaludes, Verónica|||0000-0003-2139-3360Prats, Clara|||0000-0002-1398-7559Prieto-Alhambra, Daniel|||0000-0002-3950-6346Alvarez-Lacalle, Enrique|||0000-0001-6824-6857COVID-19SeverityEcological studyCohortsSubstitution modelSeverity and vaccination statusWe aim to compare the severity of infections between omicron and delta variants in 609,352 SARS-CoV-2 positive cases using local hospitalization, vaccination, and variants data from the Catalan Health Care System (which covers around 7. 8 million people). We performed a substitution model to establish the increase in transmissibility of omicron using variant screening data from primary care practices (PCP) and hospital admissions. In addition, we used this data from PCP to establish the two periods when delta and omicron were, respectively, dominant (above 95% of cases). After that, we performed a population-based cohort analysis to calculate the rates of hospital and intensive care unit (ICU) admissions for both periods and to estimate reduction in severity. Rate ratios (RR) and 95% confidence intervals (95% CI) were calculated and stratified by age and vaccination status. In a second analysis, the differential substitution model in primary care vs. hospitals allowed us to obtain a population-level average change in severity. We have included 48,874 cases during the delta period and 560,658 during the omicron period. During the delta period, on average, 3.8% of the detected cases required hospitalization for COVID-19. This percentage dropped to 0.9% with omicron [RR of 0.46 (95% CI: 0.43 to 0.49)]. For ICU admissions, it dropped from 0.8 to 0.1% [RR 0.25 (95% CI: 0.21 to 0.28)]. The proportion of cases hospitalized or admitted to ICU was lower in the vaccinated groups, independently of the variant. Omicron was associated with a reduction in risk of admission to hospital and ICU in all age and vaccination status strata. The differential substitution models showed an average RR between 0.19 and 0.50. Both independent methods consistently show an important decrease in severity for omicron relative to delta. The systematic reduction happens regardless of age. The severity is also reduced for non-vaccinated and vaccinated groups, but it remains always higher in the non-vaccinated population. This suggests an overall reduction in severity, which could be intrinsic to the omicron variant. The fact is that the RR in ICU admission is systematically smaller than in hospitalization points in the same direction. 22022-01-0120222022-01-01Articlehttp://purl.org/coar/resource_type/c_6501VoRhttp://purl.org/coar/version/c_970fb48d4fbd8a85info:eu-repo/semantics/articleapplication/pdfhttps://ddd.uab.cat/record/266427https://dx.doi.org/urn:doi:10.3389/fpubh.2022.961030reponame:Dipòsit Digital de Documents de la UABinstname:Universitat Autònoma de BarcelonaIngléseng"la Caixa" Foundation https://doi.org/10.13039/100010434 LCF/PR/GN17/50300003Agencia Estatal de Investigación https://doi.org/10.13039/501100011033 PGC2018-095456-B-I00open accesshttp://purl.org/coar/access_right/c_abf2Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.https://creativecommons.org/licenses/by/4.0/info:eu-repo/semantics/openAccessoai:ddd.uab.cat:2664272026-06-06T12:50:31Z
dc.title.none.fl_str_mv Transmissibility, hospitalization, and intensive care admissions due to omicron compared to delta variants of SARS-CoV-2 in Catalonia
A cohort study and ecological analysis
title Transmissibility, hospitalization, and intensive care admissions due to omicron compared to delta variants of SARS-CoV-2 in Catalonia
spellingShingle Transmissibility, hospitalization, and intensive care admissions due to omicron compared to delta variants of SARS-CoV-2 in Catalonia
Català, Martí|||0000-0003-3308-9905
COVID-19
Severity
Ecological study
Cohorts
Substitution model
Severity and vaccination status
title_short Transmissibility, hospitalization, and intensive care admissions due to omicron compared to delta variants of SARS-CoV-2 in Catalonia
title_full Transmissibility, hospitalization, and intensive care admissions due to omicron compared to delta variants of SARS-CoV-2 in Catalonia
title_fullStr Transmissibility, hospitalization, and intensive care admissions due to omicron compared to delta variants of SARS-CoV-2 in Catalonia
title_full_unstemmed Transmissibility, hospitalization, and intensive care admissions due to omicron compared to delta variants of SARS-CoV-2 in Catalonia
title_sort Transmissibility, hospitalization, and intensive care admissions due to omicron compared to delta variants of SARS-CoV-2 in Catalonia
dc.creator.none.fl_str_mv Català, Martí|||0000-0003-3308-9905
Coma, Ermengol|||0000-0001-8000-3321
Alonso Muñoz, Sergio|||0000-0002-3989-8757
Andrés, Cristina|||0000-0002-3200-0895
Blanco Guillermo, Ignacio|||0000-0002-7414-7481
Antón Pagarolas, Andrés, 1976-|||0000-0002-1476-0815
Bordoy, Antoni E.|||0000-0002-1165-542X
Cardona, Pere-Joan|||0000-0001-5623-7873
Fina, Francesc
Martró, Elisa|||0000-0002-2867-6649
Medina, Manuel
Mora, Núria
Saludes, Verónica|||0000-0003-2139-3360
Prats, Clara|||0000-0002-1398-7559
Prieto-Alhambra, Daniel|||0000-0002-3950-6346
Alvarez-Lacalle, Enrique|||0000-0001-6824-6857
author Català, Martí|||0000-0003-3308-9905
author_facet Català, Martí|||0000-0003-3308-9905
Coma, Ermengol|||0000-0001-8000-3321
Alonso Muñoz, Sergio|||0000-0002-3989-8757
Andrés, Cristina|||0000-0002-3200-0895
Blanco Guillermo, Ignacio|||0000-0002-7414-7481
Antón Pagarolas, Andrés, 1976-|||0000-0002-1476-0815
Bordoy, Antoni E.|||0000-0002-1165-542X
Cardona, Pere-Joan|||0000-0001-5623-7873
Fina, Francesc
Martró, Elisa|||0000-0002-2867-6649
Medina, Manuel
Mora, Núria
Saludes, Verónica|||0000-0003-2139-3360
Prats, Clara|||0000-0002-1398-7559
Prieto-Alhambra, Daniel|||0000-0002-3950-6346
Alvarez-Lacalle, Enrique|||0000-0001-6824-6857
author_role author
author2 Coma, Ermengol|||0000-0001-8000-3321
Alonso Muñoz, Sergio|||0000-0002-3989-8757
Andrés, Cristina|||0000-0002-3200-0895
Blanco Guillermo, Ignacio|||0000-0002-7414-7481
Antón Pagarolas, Andrés, 1976-|||0000-0002-1476-0815
Bordoy, Antoni E.|||0000-0002-1165-542X
Cardona, Pere-Joan|||0000-0001-5623-7873
Fina, Francesc
Martró, Elisa|||0000-0002-2867-6649
Medina, Manuel
Mora, Núria
Saludes, Verónica|||0000-0003-2139-3360
Prats, Clara|||0000-0002-1398-7559
Prieto-Alhambra, Daniel|||0000-0002-3950-6346
Alvarez-Lacalle, Enrique|||0000-0001-6824-6857
author2_role author
author
author
author
author
author
author
author
author
author
author
author
author
author
author
dc.subject.none.fl_str_mv COVID-19
Severity
Ecological study
Cohorts
Substitution model
Severity and vaccination status
topic COVID-19
Severity
Ecological study
Cohorts
Substitution model
Severity and vaccination status
description We aim to compare the severity of infections between omicron and delta variants in 609,352 SARS-CoV-2 positive cases using local hospitalization, vaccination, and variants data from the Catalan Health Care System (which covers around 7. 8 million people). We performed a substitution model to establish the increase in transmissibility of omicron using variant screening data from primary care practices (PCP) and hospital admissions. In addition, we used this data from PCP to establish the two periods when delta and omicron were, respectively, dominant (above 95% of cases). After that, we performed a population-based cohort analysis to calculate the rates of hospital and intensive care unit (ICU) admissions for both periods and to estimate reduction in severity. Rate ratios (RR) and 95% confidence intervals (95% CI) were calculated and stratified by age and vaccination status. In a second analysis, the differential substitution model in primary care vs. hospitals allowed us to obtain a population-level average change in severity. We have included 48,874 cases during the delta period and 560,658 during the omicron period. During the delta period, on average, 3.8% of the detected cases required hospitalization for COVID-19. This percentage dropped to 0.9% with omicron [RR of 0.46 (95% CI: 0.43 to 0.49)]. For ICU admissions, it dropped from 0.8 to 0.1% [RR 0.25 (95% CI: 0.21 to 0.28)]. The proportion of cases hospitalized or admitted to ICU was lower in the vaccinated groups, independently of the variant. Omicron was associated with a reduction in risk of admission to hospital and ICU in all age and vaccination status strata. The differential substitution models showed an average RR between 0.19 and 0.50. Both independent methods consistently show an important decrease in severity for omicron relative to delta. The systematic reduction happens regardless of age. The severity is also reduced for non-vaccinated and vaccinated groups, but it remains always higher in the non-vaccinated population. This suggests an overall reduction in severity, which could be intrinsic to the omicron variant. The fact is that the RR in ICU admission is systematically smaller than in hospitalization points in the same direction.
publishDate 2022
dc.date.none.fl_str_mv 2
2022-01-01
2022
2022-01-01
dc.type.none.fl_str_mv Article
http://purl.org/coar/resource_type/c_6501
VoR
http://purl.org/coar/version/c_970fb48d4fbd8a85
dc.type.openaire.fl_str_mv info:eu-repo/semantics/article
format article
dc.identifier.none.fl_str_mv https://ddd.uab.cat/record/266427
https://dx.doi.org/urn:doi:10.3389/fpubh.2022.961030
url https://ddd.uab.cat/record/266427
https://dx.doi.org/urn:doi:10.3389/fpubh.2022.961030
dc.language.none.fl_str_mv Inglés
eng
language_invalid_str_mv Inglés
language eng
dc.relation.none.fl_str_mv "la Caixa" Foundation https://doi.org/10.13039/100010434 LCF/PR/GN17/50300003
Agencia Estatal de Investigación https://doi.org/10.13039/501100011033 PGC2018-095456-B-I00
dc.rights.none.fl_str_mv open access
http://purl.org/coar/access_right/c_abf2
https://creativecommons.org/licenses/by/4.0/
dc.rights.openaire.fl_str_mv info:eu-repo/semantics/openAccess
rights_invalid_str_mv open access
http://purl.org/coar/access_right/c_abf2
https://creativecommons.org/licenses/by/4.0/
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
dc.source.none.fl_str_mv reponame:Dipòsit Digital de Documents de la UAB
instname:Universitat Autònoma de Barcelona
instname_str Universitat Autònoma de Barcelona
reponame_str Dipòsit Digital de Documents de la UAB
collection Dipòsit Digital de Documents de la UAB
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