Arcturus: What do we know about the new COVID-19 sub-variant?

According to molecular virologist Dr Vinod Balasubramaniam, emerging data from Japan showed the latest strain could be 1.2 times more infectious than the XBB.1.5 variant, another Omicron strain that emerged earlier in 2023.

He explained that Arcturus had one additional mutation in the spike protein, which has displayed potential for increased infectivity and pathogenicity in lab studies.

“As of now, it is the most transmissible strain that we have,” said Vinod, who is also Leader of the Infection and Immunity Research Strength at the Jeffrey Cheah School of Medicine and Health Sciences in Monash University Malaysia.

“The good news is that it has not shown severity in terms of symptoms and hospitalisation or an increase in mortality for the general part of the population.

“That means our previous protection from vaccines or natural infection is still holding up.”

However, he noted that the symptoms of Arcturus did differ slightly from its XBB predecessors. Common COVID-19 symptoms have previously been identified as having a high fever, cough, flu as well as loss of sense of taste and smell.

But doctors around the world, particularly those in India, have reported a rise of infected children with conjunctivitis.

“Itchy conjunctivitis or sticky eyes are symptoms that we have not witnessed in earlier COVID-19 waves,” said Vinod.

The Arcturus sub-variant has fuelled a new surge of infections in India, prompting the mask mandate to be reintroduced in several parts of the nation.

Its presence has been detected in more than 30 countries including Malaysia, where Sarawak has detected six cases linked to Arcturus as of April 20.

The World Health Organisation has also listed it as a “variant under monitoring”, noting that enhanced surveillance was required.

Vinod said it was important to remember that SARS-CoV-2 was here to stay, having continuously evolved into a human virus similar to the flu.

He added that the virus was still rapidly mutating and adapting to the human population, with over 600 Omicron sub-variant currently circulating.

“Recently we see waves of cases, hospitalisations and deaths associated with new variants every three months or so. Between waves, COVID-19 does not go away,” he said.

Similar to other countries, he expected Malaysia to experience a rise in infections, although not as big a scale as with the Alpha (B.1.1.7) and Delta (B.1.617.2) variants.

Vinod said it was important to monitor Arcturus to discover if it was more pathogenic and what could happen in terms of immune protection, among other factors.

“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.”

In light of upcoming Hari Raya Aidilfitri festivities, Vinod advised the public to mask up with well-fitted N95 masks to reduce exposure.

He added that the safest way to prevent the virus from spreading would be for symptomatic cases to stay at home.

“Look for well-ventilated areas when you are out. Open windows and ventilate your home especially when people come to visit.