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Arcturus: What you need to know about the 'one to watch' COVID variant and its new symptoms

The latest COVID variant appears to be more contagious than previous strains and is “moderately” resistant to our immune power.
The latest COVID variant appears to be more contagious than previous strains and is “moderately” resistant to our immune power. Copyright Euronews/Canva
Copyright Euronews/Canva
By Camille Bello
Published on Updated
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First detected in India, Omicron subvariant XBB.1.16 - also known as "Arcturus" - has already been reported in over 30 countries. This is what we know about it so far.


The World Health Organization (WHO) is carefully monitoring a new Omicron subvariant that is driving a surge of new COVID-19 cases in India.

XBB.1.16 - also known as "Arcturus," the name of the brightest star in the northern celestial hemisphere - was detected in 21 countries as of March 27.

The WHO upgraded it to "variant of interest" status in mid-April, with the number of countries now affected believed to be more than 30.

Scientists at the University of Tokyo suggest it could be about 1.17 to 1.27 times more infectious than Kraken, the last major omicron sub-variant, making it likely to become the next dominant strain. "This is one to watch," said Dr Maria Van Kerkhove, technical lead for COVID-19 response at the WHO, during a press conference on March 29.

Since the beginning of the coronavirus pandemic, the global health body has designated three labels to assess the potential risk of new COVID-19 strains: “variants of concern,” “variants of interest,” and “variants under monitoring”.

Variants are assigned into either category based on several respects, such as their predicted potential for expansion and probability of causing new waves, for example.

According to the WHO’s variant tracking, Alpha, Beta, Gamma, Delta and the Omicron parent lineage are now all considered "previously circulating VOCs [variants of concern]".

Arcturus, on the other hand, is now considered a VOI because of the "spread of the virus beyond borders," tweeted Muhammad Munir, Professor of Virology & Viral Zoonoses at Lancaster University in the UK.

"Because XBB.1.16 is more transmissible and possibly escaping immunity, it may become dominant in the coming months," he added.

Is Arcturus more dangerous?

Arcturus, which was first identified in January, does not appear to be more severe than any previous COVID-19 strains.

The WHO considers the "severity" and "clinical considerations for the variant" as "low".

Arcturus has, however, one additional mutation in the spike protein, which shows “high-strength of evidence for increased risk of transmission and moderate-strength of evidence for immune escape,” said the WHO.

In other words, Arcturus appears to be more contagious than previous variants and “moderately” resistant to our immune power.

In February, WHO assessed that based on its genetic characteristics and available growth rate estimates, Arcturus was likely to increase COVID-19 cases globally.

India is the country experiencing more Arcturus cases, which has in turn led to a surge of infections, putting the country’s hospitals under alert.


What are the symptoms of Arcturus?

Dr Vipin Vashishtha, a paediatrician and former head of the Indian Academy of Pediatrics Committee on Immunisation, told the Hindustan Times that Arcturus’s symptoms include a high fever - higher than in previous COVID-19 variants - a cough and "itchy" conjunctivitis, a condition that causes inflammation.

Until now, this symptom had been a rare occurrence in COVID-19 patients.

This particular symptom can cause some confusion in northern hemisphere countries at a time of the year when individuals commonly experience red, itchy eyes due to spring allergies like hay fever, Vashishtha warned. But a high fever is an effective way to rule out seasonal allergies.

Besides these newly reported symptoms, Arcturus infections resemble earlier COVID-19 strains for which symptoms include coughing, having a scratchy throat, and a runny nose. Fatigue, body aches, headache, and congestion are also common signs.


"We are in a much better situation than we were since the beginning of this pandemic," said Van Kerkhovesaid, "but the threat isn’t over…We have to remain vigilant".

Globally, nearly 3.6 million new COVID-19 cases and over 25,000 deaths were reported between February 27 and March 26, a 27 per cent and 39 per cent decrease respectively compared to the previous 28 days.

Of the total cases, Arcturus accounted for 45.1 per cent of cases from March 6-12, up from 35.6 per cent during the same days in February.

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