The new Covid variant NB.1.8.1 is driving infections in Australia. A virologist explains what you need to know | Lara Herrero for the Conversation
Share this @internewscast.com

As we enter the colder months in Australia, Covid is making headlines again, this time due to the emergence of a new variant: NB.1.8.1.

Last week, the World Health Organization designated NB.1.8.1 as a “variant under monitoring”, owing to its growing global spread and some notable characteristics which could set it apart from earlier variants.

So what do you need to know about this new variant?

The current Covid situation

More than five years since Covid was initially declared a pandemic, we’re still experiencing regular waves of infections.

It is more difficult to track the occurrence of the virus nowadays, as fewer people are testing and reporting infections. But available data suggests in late May 2025 case numbers in Australia were ticking upwards.

Genomic sequencing has confirmed NB.1.8.1 is among the circulating strains in Australia, and generally increasing. Of cases sequenced up to 6 May across Australia, NB.1.8.1 ranged from less than 10% in South Australia to more than 40% in Victoria.

Wastewater surveillance in Western Australia has determined NB.1.8.1 is now the dominant variant in wastewater samples collected in Perth.

Internationally NB.1.8.1 is also growing. By late April 2025, it comprised roughly 10.7% of all submitted sequences – up from just 2.5% four weeks prior. While the absolute number of cases sequenced was still modest, this consistent upward trend has prompted closer monitoring by international public health agencies.

NB.1.8.1 has been spreading particularly in Asia – it was the dominant variant in Hong Kong and China at the end of April.

Where does this variant come from?

According to the WHO, NB.1.8.1 was first detected from samples collected in January 2025.

It is a sublineage of the Omicron variant, descending from the recombinant XDV lineage. “Recombinant” is where a new variant arises from the genetic mixing of two or more existing variants.

What does the research say?

Like its predecessors, NB.1.8.1 carries mutations in the spike protein. This is the protein on the surface of the virus that allows it to infect us – specifically via the ACE2 receptors, a “doorway” to our cells.

The mutations include T22N, F59S, G184S, A435S, V445H, and T478I. It’s early days for this variant, so we don’t have much data on what these changes mean yet. But a recent preprint (a study that has not yet been peer-reviewed) offers some clues about why NB.1.8.1 may be gathering traction.

Using lab-based models, researchers found NB.1.8.1 had the strongest binding affinity to the human ACE2 receptor of several variants tested – suggesting it may infect cells more efficiently than earlier strains.

The study also looked at how well antibodies from vaccinated or previously infected people could neutralise or “block” the variant. Results showed the neutralising response of antibodies was around 1.5 times lower to NB.1.8.1 compared with another recent variant, LP.8.1.1.

This means it’s possible a person infected with NB.1.8.1 may be more likely to pass the virus on to someone else, compared with earlier variants.

What are the symptoms?

The evidence so far suggests NB.1.8.1 may spread more easily and may partially sidestep immunity from prior infections or vaccination. These factors could explain its rise in sequencing data.

But importantly, the WHO has not yet observed any evidence it causes more severe disease compared with other variants.

Reports suggest symptoms of NB.1.8.1 should align closely with other Omicron subvariants.

Common symptoms include sore throat, fatigue, fever, mild cough, muscle aches and nasal congestion. Gastrointestinal symptoms may also occur in some cases.

How about the vaccine?

There’s potential for this variant to play a significant role in Australia’s winter respiratory season. Public health responses remain focused on close monitoring, continued genomic sequencing and promoting the uptake of updated Covid boosters.

Even if neutralising antibody levels are modestly reduced against NB.1.8.1, the WHO has noted current Covid vaccines should still protect against severe disease with this variant.

The most recent booster available in Australia and many other countries targets JN.1, from which NB.1.8.1 is descended. So it makes sense it should still offer good protection.

Ahead of winter and with a new variant on the scene, now may be a good time to consider another Covid booster if you’re eligible. For some people, particularly those who are medically vulnerable, Covid can still be a serious disease.

This article was originally published in the Conversation. Laro Herrero is an associate professor and research leader in virology and infectious disease at Griffith University

Share this @internewscast.com
You May Also Like

Groundbreaking Discovery in Alzheimer’s Treatment Could Revolutionize Disease Cure

Scientists have uncovered a new group of rogue proteins in the brain…

Unexpected Questions That Arise When Facing Incurable Cancer

Lying peacefully on the bed the man smiled and quietly exclaimed he…

Renowned Psychologist Highlights Unexpected Mounjaro Side Effect Impacting Relationships

Experts have sounded the alarm over a bizarre side effect that may…

Faulty Tests Drive Silent Epidemic Across the US, Putting Thousands at Risk for Chronic Diseases

Thousands could be at risk of suffering from a chronic disease this…

US State Faces Outbreak of Rare Medieval Disease, Officials Caution on Potential Future Cases

An Arizona resident had succumbed to the Black Death, marking the county’s…

Eliminating Guilt and Finding Hope: An NHS Change That Makes a Difference

Sometimes I feel guilty that I haven’t died yet. This isn’t the…

Doctors Dismissed My Heart Flutter as Anxiety, Until I Coughed Up Blood

Lindsay Herriott, 40, had an easy pregnancy, giving birth in September 2022…

Widely Used Supplement Causes Liver Damage, Leaving One Woman Hospitalized

A New Jersey woman has vowed never to take a supplement again…

Starmer’s NHS Strategy Overlooks Key Issue: My Daughter Passed Away After 6-Hour Ambulance Delay

A dad who lost his daughter after a six-hour ambulance wait has…

Distinguishing Between Heat Exhaustion and Sunstroke: A Doctor Explains

Dr Angela Rai, GP at The London General Practice, spoke exclusively to…