The new SARS-CoV-2 variant is growing rapidly, is more transmissible than other variants and affects a greater proportion of children under 20 years of age.
The new variant has a transmission advantage of 0.4 to 0.7 in reproduction number compared to the strain observed previously.
The results come in a preprint by a collaborative team from Imperial College London, University of Edinburgh, Public Health England (PHE), Wellcome Sanger Institute, University of Birmingham and COVID-19 Genomics UK (COG -UK) Consortium +.
New concern variant
This higher transmissibility will make control more difficult and further accentuates the urgency to implant vaccination as soon as possible. Professor Neil Ferguson Imperial College COVID-19 Response Team
All viruses undergo genetic changes called mutations and, through selection pressure, can result in different variants. The variant of SARS-CoV-2 (the virus that causes COVID-19) originally called strain 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 failures in diagnostic tests. The absence of the target S gene in a positive PCR test appears to be a highly specific marker for strain B.1.1.7, which has now been designated as Variant of Concern (VOC) 202012/01 by Public Health England.
Using a variety of statistical approaches, the team assessed the relationship between transmission and frequency of the new variant in the UK regions over time.
Higher transmission
Using the prevalence of the complete genome of different genetic variants over time and philodynamic modeling (dynamics of epidemiological and evolutionary processes), the researchers show that this variant is growing rapidly.
The study found a high correlation between the frequency of VOC and something called failure of the S gene target (SGTF) in routine PCR tests of community cases. This allowed researchers to use the frequency of SGTF as an estimate for the occurrence of VOC and non-VOC by region over time, showing that the frequency of VOC is associated with epidemic growth in almost all areas.
There is a consensus among all analyzes that VOC has a substantial transmission advantage (increased transmission compared to non-VOC), with the estimated difference in reproduction numbers between VOC and non-VOC ranging from 0.4 to 0.7, and the proportion of reproduction numbers ranging from 1.4 to 1.8.
These higher levels of infection occurred despite the high levels of social detachment in England. Extrapolation to other transmission contexts requires caution, the researchers note.
Less than 20 years most affected
The study found that individuals under the age of 20 constitute a higher proportion of VOC cases than non-VOC cases. However, it is too early to determine the mechanism behind this change according to the researchers. They explain that it may have been partially influenced by the spread of the variants, coinciding with a period when the lockdown was in effect, but schools were open. Additional research is underway on the specific nature of any changes in the way the virus affects this age group.
Dr. Erik Volz, from Imperial College London, said: “All viruses evolve and very rarely does a virus change in a way that requires a reassessment of public health policy. We found overwhelming evidence of a change in the transmissibility of variant B.1.1.7 that must be taken into account when planning our COVID-19 response in the new year. “
Prof Neil Ferguson, from Imperial College London, said: “These analyzes, which informed the UK government’s planning in recent weeks, show that the new variant of concern, B.1.1.7, has substantially higher transmissibility than previous SARS-CoV-2 viruses that circulated in the Kingdom United. This will make control more difficult and further accentuate the urgency to implant vaccination as soon as possible. “
Professor Axel Gandy of Imperial College London said:
“Until a very high proportion of the population is vaccinated, strong measures of social distance are needed to control this more transmissible variant of COVID-19. Everyone who can be vaccinated must be vaccinated. ”
Dr. Meera Chand, Covid-19 Incident Director 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 highlights the importance of doing everything we can to reduce the spread of the virus while the vaccines are being launched. The basics are still very important: obey social distance and respect the restrictions in force. “
Jeffrey Barrett of the Wellcome Sanger Institute said:
“Bringing together high-performance genomic surveillance in the UK with data from community tests across the UK and advanced statistical models has enabled us to understand how the new variant of the COVID virus spreads. It is a true proof of the scientific teamwork that everything came together so quickly. “
This research resulted from a collaboration between scientists at: (a) MRC Center for the Analysis of Global Infectious Diseases, J-IDEA, Imperial College London; (b) Department of Mathematics, Imperial College London; (b) Institute for 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 new coronavirus (COVID-19) in December 2019, the Imperial College COVID-19 Response Team has adopted a policy of immediately sharing the results of research on the development of the pandemic.