The COVID variant first detected in Kent spreads more easily but does not increase disease severity, according to two studies.
Known as B117, it is now dominant in the US, the UK and a number of other countries.
The studies concluded there is no evidence that infected people get worse symptoms or have more risk of developing long COVID.
Viral load and the reproduction (R) number were higher however, adding to evidence that it’s more transmissible.
The authors of both studies said their findings differed from some other research exploring the variant’s severity, and urged more work on the subject.
The first paper – a whole-genome sequencing and cohort study – looked at 341 people with COVID admitted to two London hospitals in November and December last year.
The Kent variant was present in 198 (58%) and 143 (42%) had another variant.
But there was no evidence of a link between B117 and more serious disease, with 72 of 198 (36%) becoming extremely ill or dying with the Kent variant, versus 38% in those with another type.
Sixteen percent died with B117 within 28 days, compared with 17% for the other group.
"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 B117 differs in severity or death in hospitalised patients from the strain of the first wave," said virologist Dr Eleni Nastouli.
A second study analysed self-reported data from nearly 37,000 users of the COVID Symptom Study app who tested positive between September and December, when the proportion of Kent variant cases increased in London and the South East.
It also showed increased transmissibility, with B117 increasing the R number by an estimated 1.35 times compared with the original strain – in line with previous studies.
However, the variant didn’t appear to alter symptoms and "clearly responded to lockdown measures and doesn’t appear to escape immunity gained by exposure to the original virus", said Dr Claire Steves from King’s College London, who co-led the study.
Vaccines being used in the UK still appear to offer a strong level of protection against the Kent variant but may have reduced effectiveness against the much less common Brazil and South Africa variants, according to other research.
The latest two studies research are published in The Lancet Infectious Diseases and Public Health journals.