More than one in ten cases of coronavirus in the UK are now due to the latest "Delta plus" mutation, known in Britain as AY.4.2.
This mutation is more contagious, but as less contagious than the original Delta variant.
The data come from the REACT-1 regular study at Imperial College London. The study shows that the dispersion of Delta plus increases by 2,8% every day from September onwards.
Sampling tests of about 100.000 people in England from October 19 to November 5 showed that 11,8% were carriers of this variant.
The same data show, however, that only 33% of these carriers had the typical symptoms of the coronavirus (fever, persistent cough, loss of taste or smell), compared with 46% in the case of carriers of the Delta mutation, which is still the dominant.
It turns out that the majority of Delta plus operators did not have any other symptoms of the disease, which implies that the mutation is associated with a lower risk of hospitalization and death than Delta.
In addition, there does not appear to be a significant reduction in vaccine efficacy in Delta plus carriers.
REACT Program Director Professor Paul Eliot said: "We do not know why Delta Plus is more contagious. However, it seems to cause symptoms less often, which is a good thing. "
His colleague Professor Crystal Donnelly commented that it is not clear how the Delta plus mutation with its special characteristics will affect the evolution of the pandemic. "If it is less likely to cause symptoms, then it means it is less diagnosed and the carriers will go outside. On the other hand, if they do not cough, they may transmit it at a shorter distance than in other cases. "
The UK Health Insurance Agency declared AY.4.2 "mutation under investigation" on 20 October.
At the same time, data from the latest REACT-1 study show that the booster dose is extremely effective, as it reduces the risk of infection by 2/3 compared to those who have only received the two doses of the vaccine.
Also, a single dose of the vaccine in minors reduces the risk of coronavirus infection by 56% compared to children who are not vaccinated.
(KYPE / THG / GBA)