ArticleEClinicalMedicine2022
Severe hospital events following symptomatic infection with Sars-CoV-2 Omicron and Delta variants in France, December 2021-January 2022: A retrospective, population-based, matched cohort study.
Article in EClinicalMedicine, 2022. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 40 papers, 8 of them syntheses that pooled it.
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Who cites it
40 citing papers in PubMed, 8 syntheses or guidelines pooled it.
- Pooled it
- Comparison of Omicron and Delta Variants of SARS-CoV-2: A Systematic Review of Current Evidence.Infectious disorders drug targets · 2024Pooled it
- Effectiveness of the pre-Omicron COVID-19 vaccines against Omicron in reducing infection, hospitalization, severity, and mortality compared to Delta and other variants: A systematic review.Human vaccines & immunotherapeutics · 2023Pooled it
- The relative prevalence of the Omicron variant within SARS-CoV-2 infected cohorts in different countries: A systematic review.Human vaccines & immunotherapeutics · 2023Pooled it
- Pooled it
- The risk of mortality and severe illness in patients infected with the omicron variant relative to delta variant of SARS-CoV-2: a systematic review and meta-analysis.Irish journal of medical science · 2023Pooled it
- Severity and outcomes of Omicron variant of SARS-CoV-2 compared to Delta variant and severity of Omicron sublineages: a systematic review and metanalysis.BMJ global health · 2023Pooled it
- Severity of the Omicron SARS-CoV-2 variant compared with the previous lineages: A systematic review.Journal of cellular and molecular medicine · 2023Pooled it
- Efficacy and Safety of 5-Day Oral Ensitrelvir for Patients With Mild to Moderate COVID-19: The SCORPIO-SR Randomized Clinical Trial.JAMA network open · 2024Trial
- Efficacy and Safety of Ensitrelvir in Patients With Mild-to-Moderate Coronavirus Disease 2019: The Phase 2b Part of a Randomized, Placebo-Controlled, Phase 2/3 Study.Clinical infectious diseases : an official publication of the Infectious Diseases Society of America · 2023Trial
- Dual inflammation in schizophrenia infected with COVID-19: Impact on cognitive function.Brain, behavior, & immunity - health · 2025Article
- SARS-CoV-2 Variants: Genetic Insights, Epidemiological Tracking, and Implications for Vaccine Strategies.International journal of molecular sciences · 2025Review
- Article
- Exploring the Replication and Pathogenic Characteristics of Alpha, Delta, and Omicron Variants of SARS-CoV-2.International journal of molecular sciences · 2024Article
- Article
- Safety, efficacy and immunogenicity of aerosolized Ad5-nCoV COVID-19 vaccine in a non-inferiority randomized controlled trial.NPJ vaccines · 2024Article
- Article
- Substitution spectra of SARS-CoV-2 genome from Pakistan reveals insights into the evolution of variants across the pandemic.Scientific reports · 2023Article
- Comparison of the clinical characteristics of SARS-CoV-2 Delta (B.1.617.2) and Omicron (B.1.1.529) infected patients from a single hospitalist service.BMC infectious diseases · 2023Article
- Long-term monitoring of COVID-19 prevalence in raw and treated wastewater in Salvador, the largest capital of the Brazilian Northeast.Scientific reports · 2023Article
Corrections and comments
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Authors and funding
10 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
Background: A rapid increase in incidence of the SARS-CoV-2 Omicron variant (sub-lineage BA.1) occurred in France in December 2021, while the Delta variant was prevailing since July 2021. We aimed to determine whether the risk of a severe hospital event following symptomatic SARS-CoV-2 infection differs for Omicron versus Delta. Methods: We conducted a retrospective cohort study to compare severe hospital events (admission to intensive care unit or death) between Omicron and Delta symptomatic cases matched according to week of virological diagnosis and age. The analysis was adjusted for age, sex, vaccination status, presence of comorbidities and region of residence, using Cox proportional hazards model. Findings: Between 06/12/2021-28/01/2022, 184 364 cases were included, of which 931 had a severe hospital event (822 Delta, 109 Omicron). The risk of severe event was lower among Omicron versus Delta cases; the difference in severity between the two variants decreased with age (adjusted Hazard Ratio (aHR)=0·13 95%CI: 0·08-0·20 among 40-64 years, aHR=0·50 95%CI: 0·26-0.98 among 80+ years). The risk of severe event increased with the presence of comorbidities (for very-high-risk comorbidity, aHR=4·15 95%CI: 2·86-6·01 among 40-64 years) and in males (aHR=2·28 95%CI: 1·82-2·85among 40-64 years) and was higher in unvaccinated compared to primo-vaccinated (aHR=7·29 95%CI: 5·58-9·54 among 40-64 years). A booster dose reduced the risk of severe hospital event in 80+ years infected with Omicron (aHR=0·29; 95%CI: 0·12-0·69). Interpretation: This study confirms the lower severity of Omicron compared to Delta. However, the difference in disease severity is less marked in the elderly. Further studies are needed to better understand the interactions between age and severity of variants. Funding: The study was performed as part of routine work at Public Health France.
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