The increased infectiousness of the UK coronavirus variant could be because people stay sicker for longer, a small study has suggested.
Tom Whipple, Science Editor www.thetimes.co.uk
The research, conducted using data from 65 US basketball players and staff who had contracted Covid-19, found that the seven infected with the new variant were ill for about 13 days, compared with eight days for the 58 who contracted the old variant.
If confirmed, the study may also mean that countries need to extend the length of time that people self-isolate.
“We thought [the UK variant’s] increased infectiousness was due to higher viral load,” Eric Topol, director of the Scripps Research Translational Institute, said. The new data, he said, “suggests it’s related to . . . longer duration of infections”.
However, scientists caution that the findings come from a small sample.
The study, by researchers from Harvard University, was only possible because of regular testing in the US National Basketball Association. People typically only get a test when they are symptomatic, and after testing positive take no further tests, meaning it is possible to chart neither the beginning nor end of the infection. The NBA, however, tests daily, and — unusually — continues to do so when players test positive, meaning the full course of the infection can be monitored.
Those infected with the old variant took two days from the detection of the virus to reach peak viral load. It then took six days until the virus was undetectable. Among those with the new variant, the duration was five and eight days respectively.
Dr Jenny Rohn of University College London said that a larger study was needed, but that the findings would explain the strain’s infectiousness. “The study also has serious implications for the current quarantine period of ten days, given that the Kent variant was shown to be at large in the infected person for an average of 13 days,” she said.
Dr Simon Clarke of Reading University said that it hinted at why the variant was more deadly, speculating that the increased time “gives greater opportunity for the immune system to overreact and kill the patient”.