The highly infectious coronavirus variant B.1.1.7, which appeared in Kent in September 2020, arrived in the United States on November 6, new research shows.
He is believed to have mutated in a single patient in England struggling with a critical case of Covid-19, which forced the virus to adapt by changing its genetic code.
Researchers at the University of Arizona studied the genomes of 50 B.1.1.7 infections in the U.S. and traced their lineage to determine when the mutated variant first appeared in the U.S.
They found two groups of infections, one in California and one in Florida, which originated on November 6 and November 23, respectively – the first being about six weeks before SAGE told the government about the new variant and the secretary of Matt Hancock to announce to the public.
This retrospective study has the benefit of genomic and retrospective analysis, and the first real case of the Kent strain was not diagnosed in an American until December 29.
“It is striking that this strain was already established in the United States for about 5-6 weeks before B.1.1.7 was first identified as a variant of concern in the UK in mid-December,” the researchers wrote.
“And it may have been circulating in the United States for almost two months before it was first detected, on December 29, 2020.”
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The new variants of the coronavirus have mutations in the spike protein, which are essential for immune system antibodies to cling to and destroy. Changing their shape makes it harder for the body to catch the virus
The study has not yet been peer-reviewed, but is available online as a prepress.
The exact origin of the Kent variant is unknown, but it is believed to have arisen in mid-September.
Dr Susan Hopkins, a senior public health official in England (PHE), said in December that there was originally “nothing that would particularly point out that this was a cause for concern as the variants come and go”.
Mutations in viruses occur all the time, the vast majority being harmless or harmful to the pathogen.
However, by chance, adjustments to the viral code sometimes give it a survival advantage and increase its success, often making it more infectious and easier to spread.
This is what is thought to have occurred in variant B.1.1.7, which previous studies have found to be more abundant in the upper respiratory tract.
A mutation in the spike protein – which protrudes from the coronavirus and hijacks human cells – made it better for infecting people.
This mutation called N501Y is also found in South African and Brazilian variants that have already been identified.
Arizona-based researchers found that all California cases share another minor mutation, which is seen in only 1.2 percent of European B.1.1.7 cases.
This, they say, indicates that a single introductory event, probably from an international trip, sowed the variant in California, where it spread from person to person.
A similar trend was observed for the Florida case batch, which was very similar to the most common type of B.1.1.7 seen in the United Kingdom.
This is a ‘strong indication that they are also descended from a single introduction event’, say the scientists.
At least three major variants of the coronavirus have been detected in Britain in recent months – from Kent, South Africa and Brazil – and appear to be evolving to spread more quickly and escape from some parts of the immune system, although scientists still do not find that anyone has but has gone so far as to let the vaccines pass completely
When the UK government revealed that the variant was probably the reason for an increase in local UK cases in mid-December, it plunged southeast, London and eastern England into Level 3 restrictions.
UK government scientific consultants have proclaimed that it is up to 70 percent more infectious than the dominant variant previously and encourage people to stay home to prevent transmission.
It is now believed to be responsible for more than 60 percent of all UK cases, but in California, between December 27 and January 2, only 0.4 percent of cases were of the Kent variant. At a comparable point in the UK, that figure was 1.2 percent.
“This suggests that the dynamics of B.1.1.7 may be slightly less explosive in California compared to its original epicenter in England,” say the researchers.
‘Clade 2 in Florida (population 21 million), on the other hand, exhibited faster displacement than non-B.1.1.7.,’ Write the researchers.
Here, it was responsible for 0.7 percent of cases 34 days after its first appearance in the state and “at a comparable point in the outbreak of B.1.1.7 in England B.1.1.7 was responsible for about 0.1 per percent of all cases “.
‘Consequently, although it is evidently younger than the California clade 1 strain, the Florida clade 2 strain already accounts for a greater proportion of the Florida SARS-CoV-2 epidemic than clade 1 of the SARS-CoV outbreak. -2 from California. ‘
The B.1.1.7 strain currently accounts for only 0.3 percent of coronavirus infections in the United States, the researchers say.
The reason for the different rate at which B.1.1.7 is overcoming pre-existing spots remains unknown, but the researchers provide some possibilities in their study.
‘One possibility is that the transmission advantage of B.1.1.7 may vary with the intensity of mitigation,’ they say.
‘Perhaps this strain of SARS-CoV-2, with viral loads proven to be higher in the upper airways than other variants, will be able to seed super-spreading events relatively easily when mitigation efforts are comparatively loose, but its transmission advantage is less acute when the game the field is leveled, for example, by the widespread use of a mask and the prevention of crowds indoors.
‘Another possibility is that non-B.1.1.7 strains circulating in the USA, particularly in California, may be more transmissible than non-B.1.1.7 strains in England with which B.1.1.7 has competed, giving a B.1.1.7 less transmission advantage and therefore a slower rate of displacement of non-B.1.1.7 strains. ‘