Cases of a new subvariant of Omicron Covid-19 circulating in Australia are not a cause for alarm – but they are a reminder that coronavirus still isn’t behind us, experts say.
The Arcturus subvariant – or XBB.1.16 as it is officially known – was designated a variant of interest by the World Health Organization in April after it was reported in 33 countries. The WHO has categorised the variant as low risk compared with other Omicron subvariants circulating in the community.
India, which is experiencing its highest number of Covid-19 infections in months, has reported most of the world’s Arcturus infections since the variant was first detected in January. In Australia, there were 143 cases reported as of 17 April, or 3.9% of the cases globally, according to the WHO.
Prof Peter Collignon, an expert in infectious diseases at ANU, said Arcturus may be more transmissible, but people should not panic as there is no evidence to suggest it is more severe than other Omicron subvariants.
“We’ve got very good protection now against dying and getting into hospital and that’s because of a mixture of vaccines and immunity from natural infection, but we’ve also got drugs and other interventions to decrease your risk,” he said.
He said it was unlikely any new subvariant of Omicron will be classed as a variant of concern.
Dr Sarah Palmer, an expert in infectious diseases and co-director of the centre for virus research at the Westmead institute for medical research, said the new subvariant reaching Australian shores is a reminder that Covid-19 is not behind us.
She said Australians should remain vigilant with keeping their boosters up to date. The Australian technical advisory group on immunisation recommends adults with comorbidities, or who are aged 65 and over, should get a booster if their last dose or infection was six months ago or longer.
According to the WHO, Arcturus may become dominant in some countries, but the strain has also proved to be no more severe than previous variants. In India there has been a slight increase in bed occupancy at hospitals, the WHO reported, but it is much lower than during previous Covid-19 waves.
Collignon said it was difficult to know yet whether Arcturus will become the dominant strain in Australia. The numbers are still low, that could change during winter, he said.
“Omicron forms about 95% [of infections] but it’s like a subvariant soup,” he said. “Each one goes up and down with time and it’s not very predictable.”
Palmer said Omicron cases are increasing in Australia, particularly in New South Wales, although she said she would not yet classify the uptick as the start of a new Covid-19 wave. The rise was to be expected, given people are spending more time indoors as the weather turns colder, she said.
Last week, there were 11,523 people diagnosed with Covid-19 in NSW, a 3.7% increase form the previous week. Emergency department presentations increased by 15 from the previous week to 266.
