WHO Flags Variant as Threat
The World Health Organization has designated the new COVID variant NB.1.8.1 as a “variant under monitoring.” This follows its rapid growth in global prevalence and concerning mutations. NB.1.8.1 is now the dominant variant in China and Hong Kong.
Cases Increase Across Australia
Australian case numbers have been rising since May. NB.1.8.1 now accounts for more than 40 per cent of sequenced cases in Victoria. The variant represents about 25 per cent of cases in Western Australia and New South Wales. Queensland has recorded 20 per cent while South Australia has reported under 10 per cent.
Griffith University virologist Associate Professor Lara Herrero said, “The new strain is now the dominant coronavirus strain in China and Hong Kong and, in Australia, we’re seeing it pretty much everywhere.” She added, “There is a prediction that this might start taking over other strains, but it’s early days, so we’ll just wait and see.”
A new COVID variant, NB.1.8.1, is on the rise in Australia
Wastewater Data Confirms Spread
Wastewater surveillance in Perth has confirmed NB.1.8.1 as the dominant strain in Western Australia. National genomic sequencing shows its continued spread. Up to 6 May, it was already widespread across several states.
Global Surveillance Indicates Growth
Globally, NB.1.8.1 comprised 10.7 per cent of all sequenced cases by late April. This marks a significant rise from 2.5 per cent four weeks earlier. Though absolute numbers remain low, the consistent upward trend has prompted intensified monitoring.
Genetic Origins and Mutations
The WHO identified NB.1.8.1 in samples collected in January 2025. It is a sublineage of Omicron and descends from the recombinant XDV lineage. Recombinant variants result from the genetic mixing of earlier strains.
This variant carries multiple mutations in the spike protein, including T22N, F59S, G184S, A435S, V445H, and T478I. The spike protein helps the virus bind to human cells through ACE2 receptors.
Research Reveals Higher Binding Efficiency
A recent preprint study found NB.1.8.1 binds more strongly to the ACE2 receptor than earlier strains. Researchers used lab-based models to determine infection potential. The study also examined antibody responses in vaccinated and previously infected individuals.
Neutralising response was around 1.5 times lower compared to variant LP.8.1.1. This suggests NB.1.8.1 may spread more easily between people. Lower neutralisation means infected individuals could transmit the virus more readily.
No Evidence of Increased Severity
Dr Herrero said, “We’re still seeing the same symptoms like fevers, cough, runny nose, headaches, some people are getting whole body aches and some are getting gastro symptoms.” WHO has confirmed there is no indication NB.1.8.1 causes more severe illness.
Common Symptoms Remain the Same
Symptoms remain consistent with other Omicron subvariants. Patients often experience sore throat, fatigue, fever, muscle aches, nasal congestion, and mild cough. Gastrointestinal issues may also occur in some cases.
Vaccination Still Recommended
Current vaccines continue to offer protection against severe illness. WHO confirmed the existing vaccines, including the JN.1-targeted booster, should still provide defence. NB.1.8.1 descends from JN.1, which the latest vaccine formulation targets.
Dr Herrero said, “This new strain is a sublineage of Omicron and descends from the JN1 variant, which is what the current vaccine protects against.” She urged people to stay protected. “The flu is nasty this season too so I’d very strongly recommend everyone get their yearly flu vaccine and JN1 COVID booster — it’s the best way you’re going to be protected if you haven’t had COVID in the last six months,” she said.
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Vaccination Rates Remain Low
Only 6.6 per cent of Australian adults have received a COVID vaccine in the past six months. Health Minister Mark Butler urged the public to act. “I do encourage, particularly as we head into winter, for people to think about the last time they got a COVID vaccine,” he said. “Older Australians are strongly encouraged and recommended to get that booster. But certainly everyone else is eligible for a free COVID booster, if they’ve not had one in the last 12 months at their local pharmacy or GP.”
Emergency Presentations Increase
Hospitals are seeing more respiratory cases. Dr Herrero said, “We’re seeing a lot of cases in the community coming through the [emergency department] but it’s likely we’re heavily under-reporting because COVID reporting is no longer mandatory.”
Expert Emphasises Public Measures
Dr Michael Bonning, Australian Medical Association NSW chair of public health, highlighted key prevention efforts. “Individual variants are probably less important than overall societal factors such as whether people are keeping up to date with boosters,” he said. He added that respiratory infections are rising nationwide. “We are expecting a spike in cases over the coming weeks with an expectation of a particularly difficult winter respiratory season because of what we have seen in the northern hemisphere,” he said.
Recent New South Wales data reported a 29.2 per cent increase in COVID-19 notifications last week. Influenza cases rose 25.9 per cent, while RSV cases climbed by 9.7 per cent.
Health Advice for the Public
Dr Herrero encouraged vigilance. “We’re probably all getting tired of these sorts of messages but I’d just say to people, just be vigilant before you get sick because that’s how you protect yourself,” she said. “Wash your hands, don’t go out in public if you’re sick and spread it to everyone, get your vaccines if you want them. If you’ve got a cough or cold I’d wear a mask because you don’t want to share that with other people.”
Continued Monitoring Ahead of Winter
Authorities continue to monitor NB.1.8.1 as winter approaches. Public health experts stress the importance of vaccines, hygiene, and staying home when unwell. The situation remains dynamic with variant surveillance ongoing.
