Eurosurv. Assessment of mortality and hospital admissions associated with confirmed infection with SARS-CoV-2 Alpha variant: a matched cohort and time

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• Gavin Dabrera[SUP]1,*[/SUP] , Hester Allen[SUP]1,*[/SUP] , Asad Zaidi[SUP]1[/SUP] , Joe Flannagan[SUP]1[/SUP] , Katherine Twohig[SUP]1[/SUP] , Simon Thelwall[SUP]1[/SUP] , Elizabeth Marchant[SUP]1[/SUP] , Nurin Abdul Aziz[SUP]1[/SUP] , Theresa Lamagni[SUP]1[/SUP] , Richard Myers[SUP]1[/SUP] , André Charlett[SUP]1[/SUP] , Fernando Capelastegui[SUP]1[/SUP] , Dimple Chudasama[SUP]1[/SUP] , Tom Clare[SUP]1[/SUP] , Flavien Coukan[SUP]1[/SUP] , Mary Sinnathamby[SUP]1[/SUP] , Neil Ferguson[SUP]2[/SUP] , Susan Hopkins[SUP]1[/SUP] , Meera Chand[SUP]1[/SUP] , Russell Hope[SUP]1[/SUP] , Meaghan Kall[SUP]1[/SUP] , on behalf of the COG-UK Consortium[SUP]3[/SUP]

Background

The emergence of the SARS-CoV-2 Alpha variant in England coincided with a rapid increase in the number of PCR-confirmed COVID-19 cases in areas where the variant was concentrated.

Aim

Our aim was to assess whether infection with Alpha was associated with more severe clinical outcomes than the wild type.

Methods

Laboratory-confirmed infections with genomically sequenced SARS-CoV-2 Alpha and wild type between October and December 2020 were linked to routine healthcare and surveillance datasets. We conducted two statistical analyses to compare the risk of hospital admission and death within 28 days of testing between Alpha and wild-type infections: a matched cohort study and an adjusted Cox proportional hazards model. We assessed differences in disease severity by comparing hospital admission and mortality, including length of hospitalisation and time to death.

Results

Of 63,609 COVID-19 cases sequenced in England between October and December 2020, 6,038 had the Alpha variant. In the matched cohort analysis, we matched 2,821 cases with Alpha to 2,821 to cases with wild type. In the time-to-event analysis, we observed a 34% increased risk in hospitalisation associated with Alpha compared with wild type, but no significant difference in the risk of mortality.

Conclusion

We found evidence of increased risk of hospitalisation after adjusting for key confounders, suggesting increased infection severity associated with the Alpha variant. Rapid assessments of the relative morbidity in terms of clinical outcomes and mortality associated with emerging SARS-CoV-2 variants compared with dominant variants are required to assess overall impact of SARS-CoV-2 mutations.




https://www.eurosurveillance.org/content/10.2807/1560-7917.ES.2022.27.20.2100377#html_fulltext