Five people in the UK have died with the new Arcturus Covid strain as it continues to spread around the world.
The new subvariant of Covid has already spread across the UK, and is present in all regions of England apart from the North East, amid some reports it has a new symptom.
According to the latest technical briefing from the UK Health and Security Agency (UKHSA), there were at least 135 cases of Arcturus, Omicron XBB.1.16, in the UK.
This was mostly concentrated in England, where there were 120 cases of the subvariant, but Wales had eight cases, Scotland had five, and Northern Ireland had two as well.
As of earlier this month, Arcturus was present in at least 28 countries, with the majority of those cases, over 2,000, in India.
Alongside this, the United States was reported to have 357 cases as of April 14, as Singapore and Australia both had over 100 cases too.
As things stand, health chiefs warn that there is no evidence to suggest the new subvariant is more severe than past ones.
However, the new outbreak has seemingly brought on unique symptoms not previously seen in Covid strains.
Reports from doctors in India, where the strain is rife, have said they are seeing more children and adolescents with the subvariant presenting with conjunctivitis - or pink eye.
Indian paediatrician Vipn M. Vashishtha, also a member of the WHO's Vaccine Safety Net programme, said youngsters were presenting with a high fever, cold and cough, and "itchy conjunctivitis" with "sticky eyes".
"Yes, it's true that there seems to be a rise in conjunctivitis in children in India, with a certain type of conjunctivitis associated with viral infections," Dr Stephen Griffin, associate professor in virology at the University of Leeds told The Mirror.
However, he says: "I think there needs to be more studies based on that, but certainly observationally it seems to be happening."
However, Dr Michael Chang, a paediatric infections diseases expert at UTHealth Houston and Children's Memorial Hermann Hospital, told Yagoo News there isn't enough evidence to prove the new Covid subvariant is causing conjunctivitis.
"We don't have the context of whether they're seeing that in some of the regions in India," he said.
"We know their Covid cases are going up, and presumably, these kids are testing positive for Covid, but we don't know if they're testing positive for anything else either."
He explained there are other viruses which can cause pink eye - including adenovirus which is common in spring and summer.
"We are seeing adenovirus circulating," he said, "so even if Covid cases go up, unless you're doing testing for both Covid and adenovirus, which most people aren't... it may be difficult [to determine] what's causing your pink eye."
Arcturus was seemingly behind a rise in Covid cases in India that led to some mask laws being reintroduced.
In India's southern state of Kerela, Health Minister Veena George reintroduced masks for the elderly, pregnant women, and those with underlying conditions.
It was during this surge that XBB.1.16 caught the attention of experts around the world.
The World Health Organisation first detected the subvariant in January and on March 22 they designated it a variant under monitoring.
In a press conference, Maria Van Kerkhove, the World Health Organisation's technical lead for COVID-19 response, said: "Omicron is the variant of concern that remains dominant world wide and there's still more than 600 sublineages in circulation.
"One of the variants that we are looking at, is the variant that we have under monitoring. This is the XBB.1.16.
"It's very similar in profile to XBB.1.5. But has one additional mutation in the spike protein which in lab studies shows increased infectivity as well potential increased pathogenicity. So it's one that we are monitoring. It has potential changes that we need to keep a good eye on."
Like other international and global health bodies, it flagged new mutations present in XBB.1.16 that could cause problems.
One study, published by the University of Tokyo on the biology research website bioRxiv warned the subvariant was 1.2 times more infectious than the Omicron variant.
Raj Rajnarayanan, assistant dean of research and an associate professor at the New York Institute of Technology campus in Arkansas called XBB.1.16 "the big dog".
Advisory Board reported he added: "It's picking up mutations that are common in other variants that will increase its advantage further."
