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The new SARS-CoV-2 variant grows rapidly, is more transmissible than the other variants, and affects a greater proportion under the age of 20.
The new variant has a transmission advantage of 0.4 to 0.7 in reproduction number compared to the strain previously observed.
The results come from a preprint written by a collaborative team from Imperial College London, University of Edinburgh, Public Health England (PHE), Wellcome Sanger Institute, University of Birmingham and of the COVID-19 Genomics UK (COG-UK) Consortium +.
New variant of concern
This higher transmissibility will make control more difficult and further increase the urgency of deploying vaccination as quickly as possible. Professor Neil Ferguson Imperial College COVID-19 Response Team
All viruses undergo genetic changes called mutations and, through selection pressure, can give rise to different variants. The variant of SARS-CoV-2 (the virus responsible for COVID-19), originally called lineage B.1.1.7, was detected in November 2020 and is spreading rapidly across England. Several genetic changes (substitutions and deletions) have immunological significance and are associated with failed diagnostic tests. The absence of an S gene target in an otherwise positive PCR test appears to be a very specific marker for the B.1.1.7 line, which has now been designated Variant of Concern (VOC) 202012/01 by Public Health England.
Using various statistical approaches, the team assessed the relationship between transmission and frequency of the new variant across regions of the UK over time.
Better transmission
By using the whole genome prevalence of different genetic variants over time and phylodynamic modeling (dynamics of epidemiological and evolutionary processes), the researchers show that this variant grows rapidly.
The study found a high correlation between the frequency of VOCs and what is called S gene target failure (SGTF) in routine PCR testing of community cases. This allowed the researchers to use the SGTF frequency as an estimate of the occurrence of VOCs and non-VOCs by region over time, showing that the frequency of VOCs is associated with epidemic growth in almost all areas.
There is consensus among all analyzes that VOC has a substantial transmission advantage (increased transmission over non-VOC), with the estimated difference in reproduction numbers between VOC and non-VOC varying between 0, 4 and 0.7, and the reproduction number ratio varying between 1.4 and 1.8.
These higher infection levels have taken place despite high levels of social distancing in England. Extrapolation to other transmission settings requires caution, the researchers note.
Less than 20 years more affected
The study found that people under the age of 20 represented a higher proportion of VOC cases than cases without VOCs. However, it is too early to determine the mechanism behind this change according to the researchers. They explain that it may have been partly influenced by the spread of the variants coinciding with a period when the lockdown was in effect but schools were open. More research is being done on the specific nature of any change in the way the virus affects this age group.
Dr Erik Volz, from Imperial College London, said: “All viruses evolve, and very rarely will a virus change in a way that requires us to reassess public health policy. We find overwhelming evidence of a change in the transmissibility of variant B.1.1.7 that should be taken into account when planning our COVID-19 response in the new year.
Professor Neil Ferguson of Imperial College London said: “These scans, which have informed UK government planning in recent weeks, show that the new variant of concern, B.1.1.7, has significantly higher transmissibility than previous SARS-CoV-2 viruses circulating in the UK. This will make monitoring more difficult and will further increase the urgency of deploying vaccination as quickly as possible. “
Professor Axel Gandy of Imperial College London said:
“Until a very large proportion of the population has been vaccinated, strong social distancing measures are needed to control this more transmissible variant of COVID-19. Anyone who can be vaccinated should be vaccinated.”
Dr Meera Chand, Incident Director for Covid-19 at PHE, said:
“These new analyzes provide further evidence of the increased transmissibility of the new variant of COVID-19.
“We now have two licensed vaccines, but this research underscores the importance of doing everything to reduce the spread of the virus during vaccine deployment. The basics are still very important: respect social distancing and respect the restrictions in place. “
Jeffrey Barrett, from the Wellcome Sanger Institute, said:
“Combining high throughput genomic surveillance from the UK with data from community testing across the UK and advanced statistical models has allowed us to understand how the new variant of the COVID virus is spreading. It’s a true testament to the scientific teamwork that it all came together so quickly.
This research is the result of a collaboration between scientists: (a) from the MRC Center for the Analysis of Global Infectious Diseases, J-IDEA, Imperial College London; b) Department of Mathematics, Imperial College London; b) Institute of Evolutionary Biology, University of Edinburgh; c) Public Health England; d) Wellcome Sanger Institute; and e) School of Biosciences, University of Birmingham.
Since the emergence of the novel coronavirus (COVID-19) in December 2019, the COVID-19 response team at Imperial College has adopted a policy of immediately sharing research results on the developing pandemic.
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