COVID-19 variant NB.1.8.1: Everything you need to know about the new dominant strain and how our vaccines will hold up

A new COVID-19 variant is drawing global attention due to its rapid spread worldwide.

The variant — NB.1.8.1 — is set to become the dominant strain in Australia.

However, because it has mutated from known variants, the nation’s vaccines are still expected to offer decent protection.

NB.1.8.1 is already the dominant strain in Western Australia, according to wastewater surveillance reports.

“It’s taking off pretty quickly,” Deakin University Professor and Epidemiology Chair Catherine Bennett told 7NEWS.com.au.

“It is related to variants that we’ve seen, it looks like two of them have kind of combined, but it has some new mutations as well.”

These mutations have two key effects.

First, the variant appears different enough from previous strains that our immune systems don’t immediately recognize it.

This means it can evade the immune defences developed through earlier infections or vaccinations, Bennett explained.

Second, the mutations improve the variant’s ability to bind to receptors in the mucosal linings of the human body.

“It just means if you’re exposed, you’re more likely to catch it,” Bennett said.

“People just need to be aware of infection where they can, and avoid spreading it where they can — if they’ve got symptoms, no matter what it is, it’s not the time to socialise.”

NB.1.8.1 is a descendant from Omicron JN.1 — the same strain targeted by current vaccines.

“It was wise that they invested in vaccines that were trailing along that JN.1 family,” Bennett told 7NEWS.com.au.

“While the vaccine is not perfectly matched to this sub-variant, there is enough relationship with the JN.1 strain that is in the vaccine, that allows us to still have an effective vaccine.”

Perfect storm for a spike in cases

This winter marks Australia’s fifth with COVID-19 — though the worst impacts occurred in 2022, 2023, and 2024.

In recent months, Australians have relaxed their attitudes toward the virus, buoyed by a seasonal reprieve from high infection rates — a reprieve that has also lowered overall immunity.

That complacency is one of several factors creating a perfect storm for a surge in cases: winter, waning immunity, immune evasion by the new variant, and its high transmissibility.

“All those things lining up together suggest that we might be in for a bigger winter wave, possibly even than we saw last year,” Bennett said.

“It could be the first time in a year that we see COVID really starting to impact people,” she said.

Bennett noted that right now, “is the first time that people in ICU with COVID-19 has dropped to the level it has.”

These ICU rates are the lowest since 2021 — but they are expected to rise again this winter.

“The more we can do to help reduce spreading the virus around, then the better off we’ll be,” Bennett said.

At the height of the pandemic in Australia, deaths from COVID-19 were ten times higher than those from the flu.

“That’s dropped, but it is still five times higher than the flu. So COVID-19 is still to be taken seriously,” Bennett said.

‘Not more severe than the last’

The World Health Organisation recently evaluated NB.1.8.1 as a “low risk” variant overall.

That classification reflects comparisons with previous, more severe strains, but also considers current levels of population immunity and treatment availability.

“It can still make some people very sick, but it’s not more severe than the last strains we’ve seen,” Bennett said.

“The other thing the World Health Organisation looks at, is whether the treatments we have still work, that our testing measures still work, that all of that is still okay — and it is,” she said.

“Actually having a booster shot at the start of a wave gives you the best coverage you can have through those next six to eight weeks, which is how long a wave will take.”

She urged people over 65 to review their vaccination status, and reminded adults over 18 that they remain eligible for boosters.

“It pays to think about whether you’ve had an infection, and whether actually a booster might not be a bad thing at this stage.”