A Fresh Threat Emerges This Winter
As winter sets in, a new COVID variant Australia, designated NB.1.8.1, is raising concern among health experts. Officially listed by the World Health Organization (WHO) as a “variant under monitoring”, NB.1.8.1 is making its presence known through rising case numbers and growing dominance in genomic sequencing and wastewater surveillance.
Although fewer Australians are now getting tested for COVID-19, available data suggests that infections began rising in late May 2025. This surge is being closely linked to NB.1.8.1, a sublineage of the Omicron variant first detected in January this year.
A representation of how NB.1.8.1 has originated [Credit: Lara Herrero/The Conversation]
Rapid Rise in Cases Across States
Genomic data confirms that NB.1.8.1 is increasingly common across multiple states. While it accounted for less than 10% of sequenced cases in South Australia as of early May, the variant made up over 40% of sequenced cases in Victoria. In Western Australia, NB.1.8.1 has become the dominant variant in wastewater samples collected from Perth.
Internationally, NB.1.8.1 is gaining ground. It was the leading strain in Hong Kong and China by the end of April, and has steadily risen to represent over 10% of all sequenced COVID-19 cases globally by late April 2025—up from 2.5% just four weeks earlier.
What Makes NB.1.8.1 Different?
NB.1.8.1 stems from the Omicron XDV recombinant lineage. Recombinant variants arise when two or more COVID strains merge and exchange genetic material, often resulting in a virus with unique properties.
NB.1.8.1 carries several mutations in its spike protein, including T22N, F59S, G184S, A435S, V445H, and T478I. These changes may improve the virus’s ability to bind to the human ACE2 receptor, making infection more efficient.
Preliminary lab-based studies suggest NB.1.8.1 has the strongest binding affinity to human cells among recent variants tested. This means it might be easier to catch and spread than its predecessors.
Also Read: Magda Szubanski Reveals Battle with Rare Stage 4 Cancer
Are Vaccines Still Effective?
Early research indicates that while antibody neutralisation is reduced—by roughly 1.5 times—against NB.1.8.1 when compared to the LP.8.1.1 variant, COVID-19 vaccines are still effective at preventing severe illness.
The latest vaccine boosters in Australia target JN.1, the parent lineage of NB.1.8.1. As a result, health authorities believe that existing boosters should offer substantial protection, particularly against serious complications and hospitalisation.
Public health officials strongly recommend eligible individuals consider getting a booster, especially as the new COVID variant in Australia could significantly impact the winter respiratory season.
Common Symptoms of NB.1.8.1
NB.1.8.1 presents with symptoms largely consistent with earlier Omicron variants. These may include:
- Sore throat
- Fatigue
- Mild fever
- Dry or mild cough
- Muscle aches
- Nasal congestion
- Occasional gastrointestinal symptoms
There is currently no evidence that NB.1.8.1 leads to more severe disease outcomes compared to other strains. However, its increased transmissibility and partial immune evasion are causing concern.
How It Spreads and Why It Matters
One of the most notable concerns about NB.1.8.1 is that it appears to spread more easily and could potentially bypass immune protection from previous infections or vaccinations.
Given the lower testing rates in Australia, wastewater surveillance and genomic sequencing have become vital tools in tracking the variant’s progress. In Perth, for example, NB.1.8.1 now dominates the viral load found in wastewater samples, indicating widespread community transmission.
Experts warn that while the number of reported cases may seem modest, the actual spread could be far greater due to underreporting and untested symptomatic individuals.
What Should Australians Do Now?
With the new COVID variant in Australia expected to play a major role in winter infections, the message from health professionals is clear:
- Get vaccinated or receive your latest booster if eligible.
- Stay home if you feel unwell, especially with cold-like symptoms.
- Use rapid antigen tests where possible.
- Wear masks in crowded indoor spaces or if you’re at higher risk.
- Practise hand hygiene and physical distancing where practical.
While the WHO has not observed an increase in disease severity, vigilance is essential—especially for those with underlying health conditions or weakened immune systems.
Final Thoughts
Although the world is learning to live with COVID-19, NB.1.8.1 is a reminder that the virus continues to evolve. With the new COVID variant Australia story still unfolding, the situation highlights the importance of maintaining public health measures, staying informed, and continuing vaccination efforts.
The colder months ahead may challenge Australia’s healthcare system again. But with the right precautions, community awareness, and vaccine coverage, we can minimise the impact of NB.1.8.1 and safeguard vulnerable populations.
