A strain Delta subvariant of Covid-19 that is growing in the UK is less likely to lead to symptomatic Covid-19 infection, suggests a coronavirus prevalence survey, adding that overall cases dropped during the month of October.
The Imperial College London study REACT-1, released on Thursday (18), found that the subvariant, known as AY.4.2, grew to nearly 12% of sequenced samples, but only a third had “classic” symptoms of Covid -19, compared to nearly a half of those with the currently dominant Delta strain AY.4.
Two-thirds of people infected with AY.4.2 had “some” symptoms, compared with more than three-quarters with AY.4.
AY.4.2 is believed to be slightly more transmissible, but it has not been shown to cause more serious illnesses or to avoid vaccines any more easily than Delta.
The researchers said that asymptomatic people may self-isolate less, but also that people with fewer symptoms may spread the virus less easily through coughing and may also be less likely to become seriously ill.
“It appears to be less symptomatic, which is a good thing,” epidemiologist Paul Elliott told reporters.
Imperial College had released interim results that showed Covid-19 prevalence was at the highest level on record in October, with the highest infections among children.
The full results of the latest round of the study, conducted between Oct. 19 and Nov. 5, confirmed that daily reported cases and other prevalence surveys have shown that infection levels have dropped from that peak.
Elliott said there was uncertainty about whether that decline has continued, and the coming weeks should establish whether cases will rise again as schools return.
The REACT-1 study also found that booster doses reduced the risk of infection in adults by two-thirds, compared with people who received two doses.
(Editing by Steve Orlofsky)
Reference: CNN Brasil
