Cases of Covid in the UK are declining despite the emergence of a sub-variant of Arcturus, considered the most contagious strain since the start of the pandemic.
The sub-variant, technically known as XBB.1.16, caused a massive wave of infections in India and raised concerns that it could lead to another wave in the UK.
However, scientists believe that immunity developed from previous infections, as well as improved weather, could prevent the subspecies from gaining a foothold.
Arcturus was first discovered in January and has been under World Health Organization surveillance since March 22.
Last week, the UK Health Security Agency confirmed that the virus had been found in the UK despite fewer than 100 cases being reported.
Although its prevalence has doubled, Arcturus still accounts for just 0.6% of Covid cases in the UK, up from 0.4% at the beginning of last week, according to the Gisaid Global Genome Archive.
The total number of symptomatic COVID-19 cases dropped 14 percent this week from 84,394 last Monday to 72,496 on Tuesday, according to the ZOE Health Study app.
A University of Tokyo study found that Arcturus is 1.2 times more contagious than a subvariant of Kraken, which caused a 50% rise in cases in the UK earlier this year and was previously considered the most contagious strain. Both are descended from an Omicron variant with only two mutations in the spike protein.
In India, hospitals have been put on alert and mandatory face masks have been reinstated following a massive surge in Covid infections attributed to Arcturus.
Unlike the UK, India has not had a high incidence of octopuses. Professor François Balloux, director of UCL’s Institute of Genetics, said this could explain the slow development of the subvariant.
“XBB.1.16 (Arcturus) is closely related to the XBB.1.5 (Kraken) variant that caused the previous wavelet in some parts of the world,” he said. I.
“Therefore, it is expected to be best distributed in countries where XBB.1.5 is scarce, such as India and China. Conversely, in countries that had a significant number of XBB.1.5 cases earlier this year, the impact is likely to be small.”
Improved weather is also believed to have played a role in reducing the incidence.
Professor Lawrence Young, a virologist at the University of Warwick, said: “The combination of vaccination and prior exposure to other Omicron variants such as XXB.1.15 provides some cross-reactive immune protection. Better weather can also play a role in less dense mixing in poorly ventilated areas.”
However, Professor Yang warned that it was too early to discount the influence of Arcturus.
“We hope that as the summer months approach, the number of infections will decrease, but this does not mean that we should be complacent. And we have to keep an eye on new options, especially when new options come out that are not derived from the Omicron option,” he said.
“Older and clinically vulnerable people should remain vigilant and report their boosters.”
Source: I News
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