Covid Arcturus could be more transmissible than past variants thanks to one key "advantage", it's been claimed.
The subvariant has been spreading across the globe, causing mask laws to be reintroduced in India, as five Brits have died with it.
Meanwhile, as Arcturus, known as XBB.1.16, is on the rise in Australia now too, UK health chiefs are monitoring it closely.
In the past, new variants and subvariants led to increases in transmissibility or severity of the infection.
There are concerns that the same could be said for Arcturus, as health chiefs at the UK Health Security Agency (UKHSA) warned there was “early evidence” it had “advantages” that allowed it to spread faster.
They cautioned that the sample size was still too small for any definite conclusions.
XBB.1.16 emerged from two previous potent strains of Omicron, BA.1 and BA.2 which posed serious issues for the UK.
Scientists flagged the new strain's "advantage" early on, with UKHSA first monitoring it on March 6.
It has acquired three additional spike mutations which were suggested to have increased its transmissibility.
The identification of these spikes precluded a sharp increase in Arcturus cases globally, and particularly in India, which accounts for over half of the strain’s cases globally.
As things stand, there are 135 Arcturus sequences in the UK, believed to be around 104 cases as some people have been sequenced twice.
The median age for these cases was 74, continuing the trend of older Brits being more at risk, with 54 men and 50 women having caught it.
Across the UK, the strain is present in every country and region apart from the North East, being most prevalent in London, the North West and South East.
But the majority of the infections in the North West all came about in mid to late March, on the same day, suggesting it had spread at a large event.
The East of England recorded the country’s first Arcturus case and most recently it has been recorded in the North West once more, and London, according to the most recently available data.
From April 3 to April 9, Arcturus made up 2.3 per cent of the UK’s sequences and it is, along with XBB.1.9.2, seemingly the most competitive subvariant.
Globally, the strain is thought to be in 34 countries and dominant in India, Brunei, and Singapore.
But recent data from Our World in Data suggests that India’s Arcturus spike may have peaked and levelled out, and now be on the way down.
As things stand, there’s no evidence that Arcturus is more severe, or better at evading vaccines.
This is all encouraging news to scientists worldwide monitoring XBB.1.16 as the fear with Covid has long been a repeat of Omicron that is more severe and transmissible, and dodges vaccines.
