The new variant of the coronavirus detected in the United Kingdom is not more deadly or cause more serious symptoms, according to an official technical report published yesterday by the British Government, but there are indications that it is more contagious.
At the end of September, two cases of infection with a new variant of SARS-CoV-2 were detected that had a higher number of mutations than seen so far.
The variant had up to eight mutations in protein S, which is what the virus uses to enter human cells and cause infection.
Some of these mutations could give the virus an advantage in spreading or causing more serious symptoms.
The British Government calls the new variant VUI - 202012/01, which stands for Investigational Variant Number 01, December 2020. Since first detection, this new version of the virus has spread rapidly through London and parts of southern England. until it became the dominant one, according to the latest report published by the UK Public Health Agency.
On December 7, for example, 98% of the virus samples analyzed had one of the mutations that characterize this new variant, according to the work.
This mutation is a deletion: the virus loses one letter of its genome, made up of 30,000 letters.
That loss could give it a greater ability to escape the immune system, as observed in a preliminary study of a patient infected with another variant of SARS-CoV-2 that had this mutation.
The analysis of 1,769 patients infected with 202012/01 and its comparison with many others detected with conventional variants shows that there is no higher hospitalization rate or higher mortality
Also, the new UK version has another mutation in protein S, known as N501Y.
This means that there is a change in position 501 of your genome from N (asparagine) to Y (tyrosine).
This tiny biochemical change is found in the S protein that the virus uses to infect and may allow it to bind to human cells more effectively, although there is no evidence for this at this time.
New work from the British Public Health Agency notes that there appears to be a higher incidence of the new variant in south-east England, London, parts of the south-west and the county of Cumbria, in the north-west of the island, although these data should be taken with caution as they are based on the capacity for genetic sequencing of virus samples from each region, which is variable.
The analysis of 1,769 patients infected with 202012/01 and their comparison with as many detected with conventional variants shows that there is no higher hospitalization rate or higher mortality in the first group.
There is also no higher incidence of reinfections among those infected with the new variant.
What the study does see is that 202012/01 is more contagious than the rest.
The work is based on the tracking data of new infections from a contact with someone who was already infected.
In total they have analyzed almost 230,000 contacts.
Among the contacts of the 1,978 patients who had the new variant, 15.1% of the contacts were infected.
Among those with other variants, that rate was 9.8%, meaning that the new version of the virus seems 54% more contagious.
As an example, suppose current R = 1.1, infection fatality risk is 0.8%, generation time is 6 days, and 10k people infected (plausible for many European cities recently).
So we'd expect 10000 x 1.1 ^ 5 x 0.8% = 129 eventual new fatalities after a month of spread ... 2 /
- Adam Kucharski (@AdamJKucharski) December 28, 2020
At the moment these data only show a correlation between a higher incidence of cases between contacts and the presence of the new variant, but the weight of the new mutations is not known.
In any case, a 54% increase in contagion could have very serious consequences, as it could mean going from about 129 deaths per month to about 978, as explained in a tweet Adam Kucharski, mathematician and epidemiologist from the School of Hygiene and London Tropical Medicine.
"These are the most complete data available to date," explains Fernando González Candelas, a Fisabio researcher and expert in genomic analysis of the coronavirus in Spain.
“They indicate greater transmissibility in the whole of the United Kingdom.
The more statistical problem is that data are collected from various regions of England, with a predominance of the areas where this variant is spreading the most, and it is not clear if the two factors are added and in what proportion they do so.
In Denmark, where the variant has also been analyzed, this correlation has not been seen ”, he explains.
"Although there are data that point to greater transmissibility, we do not have a confirmation that it is because it is necessary to analyze the results of other countries to eliminate possible local effects of the United Kingdom in the extension of the variant.
It will take a few weeks to gather enough information to come to a clear conclusion, ”he adds.
Some of the 17 mutations of the British variant had already been detected in versions from other countries, but never had so many appeared all together.
In South Africa, another variant with the same N501Y mutation and two other changes in protein S has been associated with an increase in infections in two provinces.
The same British variant has already been detected in the Netherlands and Australia.
In Spain, Madrid has already confirmed four cases of this variant and Andalusia, five.
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