Imperial College London
Alternate

DR WES HINSLEY

Faculty of Medicine, School of Public Health

GIS/Database/HPTC Analyst Tech Support
 
 
 
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Contact

 

+44 (0)20 7594 3269w.hinsley

 
 
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Location

 

G31Norfolk PlaceSt Mary's Campus

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Summary

 

Publications

Citation

BibTex format

@techreport{Ferguson:2021:10.25561/93038,
author = {Ferguson, N and Ghani, A and Cori, A and Hogan, A and Hinsley, W and Volz, E},
doi = {10.25561/93038},
title = {Report 49: Growth, population distribution and immune escape of Omicron in England},
url = {http://dx.doi.org/10.25561/93038},
year = {2021}
}
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RIS format (EndNote, RefMan)

TY  - RPRT
AB  - To estimate the growth of the Omicron variant of concern (1) and its immune escape (2–9) characteristics, we analysed data from all PCR-confirmed SARS-CoV-2 cases in England excluding those with a history of recent international travel. We undertook separate analyses according to two case definitions. For the first definition, we included all cases with a definitive negative S-gene Target Failure (SGTF) result and specimen dates between 29/11/2021 and 11/12/2021 inclusive. For the second definition, we included cases with a positive genotype result and specimen date between 23/11/2021 and 11/12/2021 inclusive. We chose a later start date for the SGTF definition to ensure greater specificity of SGTF for Omicron.We used logistic and Poisson regression to identify factors associated with testing positive for Omicron compared to non-Omicron (mostly Delta) cases. We explored the following predictors: day, region, symptomatic status, sex, ethnicity, age band and vaccination status. Our results suggest rapid growth of the frequency of the Omicron variant relative to Delta, with the exponential growth rate of its frequency estimated to be 0.34/day (95% CI: 0.33-0.35) [2.0 day doubling time] over the study period from both SGTF and genotype data. The distribution of Omicron by age, region and ethnicity currently differs markedly from Delta, with 18–29-year-olds, residents in the London region, and those of African ethnicity having significantly higher rates of infection with Omicron relative to Delta.Hospitalisation and asymptomatic infection indicators were not significantly associated with Omicron infection, suggesting at most limited changes in severity compared with Delta.To estimate the impact of Omicron on vaccine effectiveness (VE) for symptomatic infection we used conditional Poisson regression to estimate the hazard ratio of being an Omicron case (using SGTF definition) compared with Delta, restricting our analysis to symptomatic cases and matching by da
AU  - Ferguson,N
AU  - Ghani,A
AU  - Cori,A
AU  - Hogan,A
AU  - Hinsley,W
AU  - Volz,E
DO  - 10.25561/93038
PY  - 2021///
TI  - Report 49: Growth, population distribution and immune escape of Omicron in England
UR  - http://dx.doi.org/10.25561/93038
UR  - https://www.imperial.ac.uk/media/imperial-college/medicine/mrc-gida/2021-12-16-COVID19-Report-49.pdf
UR  - http://hdl.handle.net/10044/1/93038
ER  -
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