The novel coronavirus variant first identified in the UK is not associated with more severe illness and death, but appears to lead to higher viral load which makes it more transmissible, suggests an observational study.
The study of patients in London hospitals is consistent with emerging evidence that this lineage is more transmissible than the original COVID-19 strain.
A separate observational study using data logged by 37,000 UK users of a self-reporting COVID-19 symptom app found no evidence that the B.1.1.7. variant altered symptoms or likelihood of experiencing long COVID-19.
Authors of both studies acknowledge that these findings differ from some other studies exploring the severity of the B.1.1.7. variant and call for more research and ongoing monitoring of COVID-19 variants.
The studies, published in The Lancet Infectious Diseases and The Lancet Public Health, found no evidence that people with the B.1.1.7. variant experience worse symptoms or a heightened risk of developing long COVID-19 compared with those infected with a different COVID-19 strain.
However, viral load and R number - the number of people that one infected person will pass on a virus to - were higher for B.1.1.7., adding to growing evidence that it is more transmissible than the first strain detected in Wuhan, China, in December 2019.
The emergence of variants has raised concerns that they could spread more easily and be more deadly, and that vaccines developed based on the original strain might be less effective against them.
Preliminary data on B.1.1.7. indicates that it is more transmissible, with some evidence suggesting it could also be associated with increased hospitalisations and deaths.
However, because the variant was identified only recently, these studies were limited by the amount of data available.
Findings from the new studies, which spanned the period between September and December 2020, when B.1.1.7. emerged and began to spread across parts of England, provide important insights into its characteristics that will help inform public health, clinical, and research responses to this and other COVID-19 variants.
The study in The Lancet Infectious Diseases journal is a whole-genome sequencing and cohort study involving COVID-19 patients admitted to University College London Hospital and North Middlesex University Hospital, UK, between November 9 and December 20, 2020.
"Analysing the variant before the peak of hospital admissions and any associated strains on the health service gave us a crucial window of time to gain vital insights into how B.1.1.7. differs in severity or death in hospitalised patients from the strain of the first wave," Eleni Nastouli, from University College London Hospitals NHS Foundation Trust.
The study in The Lancet Public Health journal is an ecological study that analysed self-reported data from 36,920 UK users of the COVID Symptom Study app who tested positive for COVID-19 between September and December 2020.
"We confirmed the increased transmissibility but also showed that B.1.1.7. clearly responded to lockdown measures and doesn't appear to escape immunity gained by exposure to the original virus, Claire Steves from King's College London, UK, who co-led the study, said.
"If further new variants emerge, we will be scanning for changes in symptom reporting and reinfection rates, and sharing this information with health policymakers," Steves said.
Britta Jewell, from Imperial College London, UK, who was not involved in the study, said this study adds to the consensus that B.1.1.7 has increased transmissibility.
This, Jewell said, has contributed in large part to the sharp rise in cases in the UK over the study period and beyond, as well as ongoing third waves in European countries with growing burdens of B.1.1.7 cases.
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