There are fears a new Covid-19 variant, wreaking havoc in India, could soon lead to a rapid and sudden surge in UK infections.

'Arcturus' is thought to be the most contagious variant of the virus yet and has prompted some Indian states to return to face masks as part of efforts to stem the spread.

But with cases already being identified in the UK - and the NHS struggling to deliver care amid ongoing strikes by thousands of health workers - there are concerns the country may struggle to manage another significant wave of Covid-19.

Here's everything we know so far about the new variant.

What is Arcturus?

The new Arcturus variant being watched by health officials across the world is a sub variant of the Omicron strain of coronavirus. Scientifically it is called XBB.1.16.

It is said to be a spin-off or sub variant similar to the 'Kraken' strain called XBB.1.5, which is also a relation of Omicron, and drove a wave of Covid through the UK a few months ago and was still the dominant form of the disease as late as this February.

The name Arcturus - was thought to have been chosen by online virus trackers, which have adopted a naming system that reflects mythological creatures and characters.

Arcturus means 'Guardian of the Bear' and is related to the constellation the Great Bear.

What's happening in India?

Arcturus - or XBB.1.16. - is behind a wave of Covid-19 currently sweeping the country and officials believe this variant alone is single-handedly driving up infection rates rapidly.

Such is the growing rate of infection that officials have been prompted to start mock drills to test how well prepared hospitals are to manage a new wave of the virus, while some states have also forced people to return to face masks when in public areas.

Pregnant women, the elderly and the vulnerable are also being warned to take extra care while so much illness is circulating in communities.

Cases are growing by thousands every day in some parts of India with some towns reporting a 13-fold increase in less than a month. On Friday alone the country recorded more than 11,000 new cases in less than 24 hours.

In 2021 the Delta coronavirus wave overwhelmed healthcare in India with World Health Organisation estimates suggesting the country experienced more than 4.7 million excess deaths that year as a result.

Some hospitals at the time ran out of oxygen and struggled to treat the influx of patients - hence rehearsals this time around as health care workers brace themselves for a potentially difficult few weeks and months ahead.

Is Arcturus in the UK?

While India is so far showing signs of being worst hit, data suggests Acrturus has now made its way into more than 20 countries worldwide including the US, Singapore, Australia and the UK.

With mass testing having been significantly scaled back in the UK over the last 12 months, the prevalence of Arcturus could be hard to gauge accurately.

However the UK Health Security Agency confirmed that the variant was already in the UK in its final variant report issued last month.

It has been reported that more than 50 confirmed samples of Arcturus have already been sequenced by scientists thanks to variant trackers - albeit the exact number of cases is likely to be a lot higher.

It is dangerous?

The World Health Organisation says studies show Arcturus may infect people more easily and be the most aggressive strain of coronavirus yet.

Additional research in Japan pointed to estimations that it may be 1.2 times more infectious than previous Omicron variants. However, so far there are few signs yet to suggest the virus is any more dangerous than previous strains.

Dr Maria Van Kerkhove, the WHO's Covid technical lead, explained last month: "It's been in circulation for a few months.

"We haven't seen a change in severity in individuals or in populations, but that's why we have these systems in place.

"It has one additional mutation in the spike protein which in lab studies shows increased infectivity as well as potential increased pathogenicity."

Are symptoms the same?

As with many other Covid variants - of which there are thoughts to be hundreds - the main symptoms of Arcturus continue to be a high fever, a cough and at times a sore throat.

However Dr Vipin Vashishtha, a paediatrician and former head of the Indian Academy of Paediatrics Committee on Immunisation, told The Hindustan Times in India that Arcturus’s symptoms also often included 'itchy' pinkeye - also known as conjunctivitis. Doctors in particular are seeing eye complaints in positive Arcturus cases among children.

He also this month wrote on Twitter: "For the last 2 days, have started getting paediatric Covid cases once again after a gap of 6 mo! An infantile phenotype seems emerging - treated infants w/ high fever, cold & cough, & non-purulent, itchy conjunctivitis w/ sticky eyes, not seen in earlier waves."

So why the concern?

Covid testing has plummeted to negligible levels in most parts of Europe - which means that surveillance of the virus and an understanding of how new strains are being transmitted is now far more difficult.

And there are fears that as countries move away from testing, tracing and vaccination that a more deadly strain could take hold quickly and quietly and it would be some time before it was spotted and measures to contain it could be rolled-out.

Many countries, including the UK, have also now stopped widespread coronavirus vaccination programmes and have instead chosen to focus their efforts on those that continue to be most at risk such as the elderly and those with compromised immune systems.

In England a booster programme has started this spring for those over 75 and patients of all ages deemed most at risk - but with large swathes of the population having not received a Covid jab since last year immunity in the general population could be waning just as a new, highly contagious, variant arrives.

And while it may prove to be no more dangerous than previous waves - any sudden and rapid increase in the numbers being infected will lead to increased numbers of patients with the virus requiring hospital care.

And with record numbers of people already waiting for care, and extensive delays being reported in many A&E departments, as the service battles staff shortages and the impact of strikes there is a concern it would struggle to manage another Covid-19 wave on top.

Virologist Professor Lawrence Young from the University of Warwick told The Independent that the rise of a new variant in India showed 'we’re not yet out of the woods'.

He added: "We have to keep an eye on it. When a new variant arises you have to find out if it’s more infectious, more disease-causing, is it more pathogenic? And what’s going to happen in terms of immune protection.

"These kinds of things highlight the importance of genomic surveillance but a lot of countries including our own have let our guards down a bit and we can’t be sure what variants are around and what level of infection they’re causing until we see a significant outbreak."