Risk of hospitalisation associated with infection with SARS-CoV-2 omicron variant versus delta variant in Denmark : an observational cohort study
Copyright © 2022 Elsevier Ltd. All rights reserved..
BACKGROUND: Estimates of the severity of the SARS-CoV-2 omicron variant (B.1.1.529) are crucial to assess the public health impact associated with its rapid global dissemination. We estimated the risk of SARS-CoV-2-related hospitalisations after infection with omicron compared with the delta variant (B.1.617.2) in Denmark, a country with high mRNA vaccination coverage and extensive free-of-charge PCR testing capacity.
METHODS: In this observational cohort study, we included all RT-PCR-confirmed cases of SARS-CoV-2 infection in Denmark, with samples taken between Nov 21 (date of first omicron-positive sample) and Dec 19, 2021. Individuals were identified in the national COVID-19 surveillance system database, which included results of a variant-specific RT-PCR that detected omicron cases, and data on SARS-CoV-2-related hospitalisations (primary outcome of the study). We calculated the risk ratio (RR) of hospitalisation after infection with omicron compared with delta, overall and stratified by vaccination status, in a Poisson regression model with robust SEs, adjusted a priori for reinfection status, sex, age, region, comorbidities, and time period.
FINDINGS: Between Nov 21 and Dec 19, 2021, among the 188 980 individuals with SARS-CoV-2 infection, 38 669 (20·5%) had the omicron variant. SARS-CoV-2-related hospitalisations and omicron cases increased during the study period. Overall, 124 313 (65·8%) of 188 980 individuals were vaccinated, and vaccination was associated with a lower risk of hospitalisation (adjusted RR 0·24, 95% CI 0·22-0·26) compared with cases with no doses or only one dose of vaccine. Compared with delta infection, omicron infection was associated with an adjusted RR of hospitalisation of 0·64 (95% CI 0·56-0·75; 222 [0·6%] of 38 669 omicron cases admitted to hospital vs 2213 [1·5%] of 150 311 delta cases). For a similar comparison by vaccination status, the RR of hospitalisation was 0·57 (0·44-0·75) among cases with no or only one dose of vaccine, 0·71 (0·60-0·86) among those who received two doses, and 0·50 (0·32-0·76) among those who received three doses.
INTERPRETATION: We found a significantly lower risk of hospitalisation with omicron infection compared with delta infection among both vaccinated and unvaccinated individuals, suggesting an inherent reduced severity of omicron. Our results could guide modelling of the effect of the ongoing global omicron wave and thus health-care system preparedness.
FUNDING: None.
| Errataetall: |
CommentIn: Lancet Infect Dis. 2022 Jul;22(7):914-915. - PMID 35468333 |
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| Medienart: |
E-Artikel |
| Erscheinungsjahr: |
2022 |
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| Erschienen: |
2022 |
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Zur Gesamtaufnahme - volume:22 |
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| Enthalten in: |
The Lancet. Infectious diseases - 22(2022), 7 vom: 04. Juli, Seite 967-976 |
| Sprache: |
Englisch |
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Date Completed 28.06.2022 Date Revised 01.03.2023 published: Print-Electronic CommentIn: Lancet Infect Dis. 2022 Jul;22(7):914-915. - PMID 35468333 Citation Status MEDLINE |
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| doi: |
10.1016/S1473-3099(22)00154-2 |
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| 245 | 1 | 0 | |a Risk of hospitalisation associated with infection with SARS-CoV-2 omicron variant versus delta variant in Denmark |b an observational cohort study |
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| 500 | |a CommentIn: Lancet Infect Dis. 2022 Jul;22(7):914-915. - PMID 35468333 | ||
| 500 | |a Citation Status MEDLINE | ||
| 520 | |a Copyright © 2022 Elsevier Ltd. All rights reserved. | ||
| 520 | |a BACKGROUND: Estimates of the severity of the SARS-CoV-2 omicron variant (B.1.1.529) are crucial to assess the public health impact associated with its rapid global dissemination. We estimated the risk of SARS-CoV-2-related hospitalisations after infection with omicron compared with the delta variant (B.1.617.2) in Denmark, a country with high mRNA vaccination coverage and extensive free-of-charge PCR testing capacity | ||
| 520 | |a METHODS: In this observational cohort study, we included all RT-PCR-confirmed cases of SARS-CoV-2 infection in Denmark, with samples taken between Nov 21 (date of first omicron-positive sample) and Dec 19, 2021. Individuals were identified in the national COVID-19 surveillance system database, which included results of a variant-specific RT-PCR that detected omicron cases, and data on SARS-CoV-2-related hospitalisations (primary outcome of the study). We calculated the risk ratio (RR) of hospitalisation after infection with omicron compared with delta, overall and stratified by vaccination status, in a Poisson regression model with robust SEs, adjusted a priori for reinfection status, sex, age, region, comorbidities, and time period | ||
| 520 | |a FINDINGS: Between Nov 21 and Dec 19, 2021, among the 188 980 individuals with SARS-CoV-2 infection, 38 669 (20·5%) had the omicron variant. SARS-CoV-2-related hospitalisations and omicron cases increased during the study period. Overall, 124 313 (65·8%) of 188 980 individuals were vaccinated, and vaccination was associated with a lower risk of hospitalisation (adjusted RR 0·24, 95% CI 0·22-0·26) compared with cases with no doses or only one dose of vaccine. Compared with delta infection, omicron infection was associated with an adjusted RR of hospitalisation of 0·64 (95% CI 0·56-0·75; 222 [0·6%] of 38 669 omicron cases admitted to hospital vs 2213 [1·5%] of 150 311 delta cases). For a similar comparison by vaccination status, the RR of hospitalisation was 0·57 (0·44-0·75) among cases with no or only one dose of vaccine, 0·71 (0·60-0·86) among those who received two doses, and 0·50 (0·32-0·76) among those who received three doses | ||
| 520 | |a INTERPRETATION: We found a significantly lower risk of hospitalisation with omicron infection compared with delta infection among both vaccinated and unvaccinated individuals, suggesting an inherent reduced severity of omicron. Our results could guide modelling of the effect of the ongoing global omicron wave and thus health-care system preparedness | ||
| 520 | |a FUNDING: None | ||
| 650 | 4 | |a Journal Article | |
| 650 | 4 | |a Observational Study | |
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| 700 | 1 | |a Stegger, Marc |e verfasserin |4 aut | |
| 700 | 1 | |a Legarth, Rebecca |e verfasserin |4 aut | |
| 700 | 1 | |a Møller, Camilla Holten |e verfasserin |4 aut | |
| 700 | 1 | |a Skov, Robert Leo |e verfasserin |4 aut | |
| 700 | 1 | |a Valentiner-Branth, Palle |e verfasserin |4 aut | |
| 700 | 1 | |a Voldstedlund, Marianne |e verfasserin |4 aut | |
| 700 | 1 | |a Fischer, Thea K |e verfasserin |4 aut | |
| 700 | 1 | |a Simonsen, Lone |e verfasserin |4 aut | |
| 700 | 1 | |a Kirkby, Nikolai Søren |e verfasserin |4 aut | |
| 700 | 1 | |a Thomsen, Marianne Kragh |e verfasserin |4 aut | |
| 700 | 1 | |a Spiess, Katja |e verfasserin |4 aut | |
| 700 | 1 | |a Marving, Ellinor |e verfasserin |4 aut | |
| 700 | 1 | |a Larsen, Nicolai Balle |e verfasserin |4 aut | |
| 700 | 1 | |a Lillebaek, Troels |e verfasserin |4 aut | |
| 700 | 1 | |a Ullum, Henrik |e verfasserin |4 aut | |
| 700 | 1 | |a Mølbak, Kåre |e verfasserin |4 aut | |
| 700 | 1 | |a Krause, Tyra Grove |e verfasserin |4 aut | |
| 700 | 0 | |a Omicron-Delta study group |e verfasserin |4 aut | |
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| 700 | 1 | |a Sieber, Raphael Niklaus |e investigator |4 oth | |
| 700 | 1 | |a Ingham, Anna Cäcilia |e investigator |4 oth | |
| 700 | 1 | |a Overvad, Maria |e investigator |4 oth | |
| 700 | 1 | |a Agermose Gram, Mie |e investigator |4 oth | |
| 700 | 1 | |a Kristensen Lomholt, Frederikke |e investigator |4 oth | |
| 700 | 1 | |a Hallundbæk, Louise |e investigator |4 oth | |
| 700 | 1 | |a Hjorth Espensen, Caroline |e investigator |4 oth | |
| 700 | 1 | |a Gubbels, Sophie |e investigator |4 oth | |
| 700 | 1 | |a Karakis, Marianne |e investigator |4 oth | |
| 700 | 1 | |a Lauenborg Møller, Karina |e investigator |4 oth | |
| 700 | 1 | |a Schytte Olsen, Stefan |e investigator |4 oth | |
| 700 | 1 | |a Harboe, Zitta Barrella |e investigator |4 oth | |
| 700 | 1 | |a Klint Johannesen, Caroline |e investigator |4 oth | |
| 700 | 1 | |a van Wijhe, Maarten |e investigator |4 oth | |
| 700 | 1 | |a Holler, Jon Gitz |e investigator |4 oth | |
| 700 | 1 | |a Dessau, Ram Benny Christian |e investigator |4 oth | |
| 700 | 1 | |a Barfred Friis, Martin |e investigator |4 oth | |
| 700 | 1 | |a Fuglsang-Damgaard, David |e investigator |4 oth | |
| 700 | 1 | |a Pinholt, Mette |e investigator |4 oth | |
| 700 | 1 | |a Vognbjerg Sydenham, Thomas |e investigator |4 oth | |
| 700 | 1 | |a Coia, John Eugenio |e investigator |4 oth | |
| 700 | 1 | |a Marmolin, Ea Sofie |e investigator |4 oth | |
| 700 | 1 | |a Fomsgaard, Anders |e investigator |4 oth | |
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| 700 | 1 | |a Rasmussen, Morten |e investigator |4 oth | |
| 700 | 1 | |a Cohen, Arieh |e investigator |4 oth | |
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