Repository logo

Risk of hospital admission for patients with SARS-CoV-2 variant B.1.1.7: cohort analysis.

Accepted version

No Thumbnail Available



Change log


Twohig, Katherine A 
Harris, Ross J 
Seaman, Shaun R 
Flannagan, Joe 


OBJECTIVE: To evaluate the relation between diagnosis of covid-19 with SARS-CoV-2 variant B.1.1.7 (also known as variant of concern 202012/01) and the risk of hospital admission compared with diagnosis with wild-type SARS-CoV-2 variants. DESIGN: Retrospective cohort analysis. SETTING: Community based SARS-CoV-2 testing in England, individually linked with hospital admission data. PARTICIPANTS: 839 278 patients with laboratory confirmed covid-19, of whom 36 233 had been admitted to hospital within 14 days, tested between 23 November 2020 and 31 January 2021 and analysed at a laboratory with an available TaqPath assay that enables assessment of S-gene target failure (SGTF), a proxy test for the B.1.1.7 variant. Patient data were stratified by age, sex, ethnicity, deprivation, region of residence, and date of positive test. MAIN OUTCOME MEASURES: Hospital admission between one and 14 days after the first positive SARS-CoV-2 test. RESULTS: 27 710 (4.7%) of 592 409 patients with SGTF variants and 8523 (3.5%) of 246 869 patients without SGTF variants had been admitted to hospital within one to 14 days. The stratum adjusted hazard ratio of hospital admission was 1.52 (95% confidence interval 1.47 to 1.57) for patients with covid-19 infected with SGTF variants, compared with those infected with non-SGTF variants. The effect was modified by age (P<0.001), with hazard ratios of 0.93-1.21 in patients younger than 20 years with versus without SGTF variants, 1.29 in those aged 20-29, and 1.45-1.65 in those aged ≥30 years. The adjusted absolute risk of hospital admission within 14 days was 4.7% (95% confidence interval 4.6% to 4.7%) for patients with SGTF variants and 3.5% (3.4% to 3.5%) for those with non-SGTF variants. CONCLUSIONS: The results suggest that the risk of hospital admission is higher for people infected with the B.1.1.7 variant compared with wild-type SARS-CoV-2, likely reflecting a more severe disease. The higher severity may be specific to adults older than 30 years.



Adolescent, Adult, Age Factors, Aged, Aged, 80 and over, COVID-19, COVID-19 Testing, Child, England, Female, Hospitalization, Humans, Male, Middle Aged, Proportional Hazards Models, Retrospective Studies, Risk Factors, SARS-CoV-2, Young Adult

Journal Title


Conference Name

Journal ISSN


Volume Title





All rights reserved
MRC (MC_PC 19074)
Medical Research Council (Unit programme number MC_UU_00002/11, SRS Unit programme number MC_UU_00002/10); MRC UKRI/DHSC NIHR COVID-19 rapid response call (grant ref: MC_PC_19074). This research was also supported by the NIHR Cambridge Biomedical Research Centre.