People traveling in the UK have contributed to a “super seed” event to spread alpha variants: research

How did the alpha mutant, the first identified COVID-19 mutant that first appeared in Toronto-Kent County, southern England, spread rapidly throughout the UK in 2020?

This is the focus of new research that will be the first to look at how B.1.1.7 evolved and hijacked the UK in the fall and winter of 2020.

Studies show Published in Journal Science on ThursdayA large number of infected individuals carrying subspecies from central locations in the United Kingdom to new areas helped the subspecies spread as fast and far as it did.

One of the largest phylogeographic analyzes ever performed, the study was conducted from Kent County to “all counties by January 19 except five counties in Wales, Scotland, Northern Ireland and England.” Spread to. The specified press release.

Alpha variants are also popular internationally, but this study focuses on their spread in the UK.

“At the beginning of December 2020, the center of COVID-19 infection in the United Kingdom rapidly shifted from northwest and northeast to London and southeast as the alpha variant became established,” said a researcher and researcher at Oxford University.

“When people traveled from London and the southeast to other parts of the UK, they” seeded “a new transmission chain for that variant. This continued as a national “super seed” event that did not begin to slow down until early January. “

Researchers examined more than 17,000 genomes of Alpha variants collected by health units in various regions between the end of September and 19 January 2021 from COVID-19 test samples representing random population selection. I did. They examined samples by location and weekly collection to map subspecies progression throughout the UK.

Alpha variants can be detected in Kent as far back as September 20, 2020. The variant had been reported by several local health authorities before the UK entered its second blockade in early November, but by the end of the blockade in early December, the alpha variant had It has spread throughout the UK.

In this study, we used aggregated phone data to find out how human movement helped spread variants. Researchers have observed that migration from the Greater London area adjacent to Kent increased at the end of the second blockade, reaching more unique locations and contributing to the spread.

After the blockade was lifted, Verity Hill, a co-author and researcher at the University of Edinburgh, said, “This variant has spread rapidly across the country due to the significant increase in human movement.”

Researchers found that exports of alpha variant cases (meaning cases resulting from the travel of infected individuals) increased from less than 600 to more than 12,000 by early December in November, including during the blockade. I found.

On December 20, restrictions were tightened in London, including a “household order”. This was consistent with the stabilization of the rate of increase in the case of exported Alpha variants. The total number of alpha variant cases did not decrease immediately due to growth in southeastern England, which offset the decrease in outbound routes from London.

Researchers said case exports began to decline from about 20,000 weekly exports only after the third national blockade in early January.

The spread map created using the data from the survey shows a large number of transmission lines branching from the Greater London area.

Color-coded maps showing when Alpha variants occurred in different regions tended to occur later in the study period in areas far from London, but in some parts of the United Kingdom that occurred early. It also shows that it wasn’t right next to London. Shows how individuals on long trips spread variants to new areas that are not geographically close to the first outbreak.

During the study period, the longest dispersal event (that is, the distance a subspecies travels from one individual to infect another at its destination) consistently occurs in the London area and spreads further than 100 km away. There was also.

Alpha mutants are more contagious than the early strains of COVID-19, releasing about 30% to 40%, but the rapid spread of the alpha mutants further enhances the initial prediction of infectivity. Some people estimate that it can be 80% more contagious.

Oliver Pybus, a professor at Oxford University and a pandemic genomics expert, said the first wave of alpha mutants from outbreaks in Kent and London to other parts of the low-infection country, how suddenly it exploded. I explained in the release that I explained.

“Initial estimate [of transmissibility] It was higher because we didn’t know how much the growth had deteriorated due to human mobility and the number of contacts with different groups of people, “said Pybus. “Importantly, as more variants emerge and spread in other countries around the world, these phenomena need to be carefully considered when assessing the inherent transmissibility of new variants. “

The study also found that their results occurred across the UK from one dominant UK source area, in contrast to their results occurring on overseas trips from places where epidemics of alpha mutants were not detected. We also note that it supports the theory that it has spread to.

This study shows that when thinking about new variants, transmission is not the only driving force, but human movement plays a major role in facilitating diffusion.