Lab Notes: Super-K flu is here … but it's not our biggest problem

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It might not feel like it where you are,

but the calendar says it's officially autumn,

which means winter is coming,

and it's time to start thinking about the seasonal flu vaccine.

And there might be even more reason to roll up your sleeve

than normal.

A fast-moving strain of influenza, known as superk,

is circulating in Australia

and has been driving up flu numbers around the world.

What should we know about this strain?

What does it mean for our 2026 flu vaccines?

And how do scientists identify

and trace viruses like this

as they mutate and spread around the planet?

This is Lab Notes from ABC Radio National.

I'm Jonathan Webb, and this week,

I'm joined by a virologist, Professor Kirstie Short

from the University of Queensland.

Hello, Kirstie.

Hi.

Now, what can you tell me about superk?

It's a fun name,

but what makes it noteworthy

compared to all the other flavors of flu that are going around?

Yeah, so basically, it's just a new variant of influenza virus.

And it's significant because it seems to be quite transmissible.

And in terms of last year's flu vaccine

for the Northern Hemisphere,

and remembering that they're on a different vaccine schedule

and season to us,

it seemed to be able to evade someone

that immunity induced by the vaccine.

So it has really been attributed to a spike in influenza cases

and in Australia, that's manifested as a spike in summer cases,

which is unusual because we know that influenza

is more of a winter virus.

That's spreading faster.

It's more transmissible.

Does it cause any worse disease?

Because anecdotally, I'm hearing terrible things

about this flu that's been looking people out through the summer.

There doesn't seem to be any evidence

that it's causing more severe disease.

I think what we are seeing,

and we did see last year, certainly in Queensland,

that there was increased rate of hospitalization,

but that really largely reflects the vaccination rate

of the population and the fact that we are really

under-vaccinated for influenza,

rather than the fact that this particular variant causes

severe disease.

Right, and I guess it's also,

if you catch it in summer,

even if you were vaccinated,

it's another few months since you had your season or flu shot.

Well, and if you were vaccinated and you courted in summer,

you had last year's vaccine and not this year's vaccine,

so then there's immunivasion,

so it's all very complex with the timing of the vaccine,

what particular vaccine you got.

That leads me to another question,

which is this year's flu vaccine for the 2026 winter,

which I guess will be available in a few weeks' time.

Do we know whether that's going to work against superk,

which is a relatively new variant

that we weren't thinking about last winter?

Yeah, so thankfully that vaccine has been updated

to include superk,

so that really gives us a very good shot.

We might know what the efficacy of that vaccine is

until the end of the flu season.

Do we know when this thing first cropped up?

You're a virologist and you're interested in these sort of

lineages and how things change over time.

I gather that in the northern hemisphere,

certainly in Britain,

where the tabloids love a good headline,

they've been dubbing at the Aussie flu.

Did it start over here, this superk strain?

What do we know about it?

Look, it emerged probably towards the end of the 2025 winter season.

It was detected in Australia,

whether it emerged there, I don't know,

because it's very hard to say,

just because something's detected somewhere,

it doesn't mean that it emerged there.

How do scientists go about trying to answer that question?

Are we constantly getting genetic sequences from viruses

and trying to kind of track their family tree?

Yeah, absolutely.

So influenza is a virus where we have incredible worlds,

the valence, and we have WHO collaborating centers,

key points around the world,

one of which is in Melbourne,

and basically they will sequence a set number of flu strains

that are just reported to them every year,

and then we can map basically how the virus evolves.

And in fact, a lot of the tracing of variants

that we did for SARS-CoV-2 was based on the fact

that we already had this system set up for influenza.

So it's an incredibly well-tracked virus.

The variants are incredibly well-tracked,

very well-described,

and that's how we can get onto these new variants pretty quickly.

How are you feeling about the 2026 winter,

because if there's a combination of slipping vaccination rates

and this very transmissible strain around,

it looks like a slightly alarming pattern of growth

before we're into winter.

Yeah, so we have been seeing in previous influenza seasons

that they've shifted a bit earlier.

Right.

And just some of the patterns of influenza has changed,

and some of that changed after COVID,

because remember we basically got rid of influenza temporarily

during COVID with all the lockdowns,

and so that shifted things.

But in terms of the upcoming winter season,

I am certainly concerned,

and I am not so concerned about this flu variant

because flu variants come and go.

Again, it's not more severe,

so that's something that's really good.

I am really concerned about the falling vaccination rates.

And we have a lot of different flu vaccines

that are now available.

They're trialing an intranasal vaccine for kids,

which as the mother of a kid who does not like getting needles,

I can attest that that would be beneficial.

So I think there's a lot of great options for vaccines.

I think we need to really have discussions

about why people aren't getting vaccines.

It's not necessarily the cost

because in some states like Queensland,

it's freely available.

I think it's people understanding the importance of this

and that the flu is not just a cold.

The flu is a serious condition

and you really don't want to get it.

You mentioned that we're under-vaccinated,

and in fact, 2025 coverage with the flu vaccine

was down to 60.5% for over 65,

who are a vulnerable group,

and down to 25.7% for under-fives.

Those are the lowest numbers since COVID.

Do we know what's going on there,

what's causing those numbers to drift?

We have a lot of discussions

about why vaccination rates have dropped,

and what we can do as scientists to try and address that.

Some of it is remnants of COVID,

where people are just sick of thinking about vaccination

and sick of thinking about infections.

Some of it is purely people just don't get around to it.

And then we are seeing an increase in vaccine hesitancy

and concern about what's in vaccines and the risk of vaccines,

even though the flu vaccine is an incredibly safe,

well-tried and tested vaccination.

So yeah, it's a combination of different factors.

It does feel like we saw a bit of a shift

in public attitudes to vaccines,

including the flu shot, I guess, post-COVID,

but in that period, right after we locked ourselves up,

that really did slash the flu numbers, didn't it?

Yeah, so absolutely, COVID changed the flu landscape,

and you know what's incredible?

All the lockdowns of COVID and the restriction on travel

and actually eliminated a strain of flu,

which is amazing.

Yeah, it's gone.

And in fact, the vaccine got updated this year.

Previously, the vaccine contained four different strains of flu,

but now because we eliminated one,

it only has to contain three strains of flu.

So we're actually just getting three strains of flu

in this year's vaccine.

What's the strain that went away?

It was the strain of influenza B,

so it was called influenza B Yamagata.

It's gone worldwide, it's really incredible.

And that's from, I guess, people staying home

and not spreading it locally,

but also not traveling internationally and taking it overseas.

Correct, we still don't fully understand why it disappeared

because you could imagine that maybe if we weren't traveling,

it would just stay in locations where it was,

and then once we opened up again, it would spread again.

So we don't fully understand it,

but it does mean that this year's vaccine

only has three viruses in it.

And yet despite those winds since COVID,

flu seasons seem to be getting worse and worse every year.

Is that just the virus bouncing back

and not enough people being vaccinated

or are there things like these new flu strains

that are also making the seasons worse?

From an evolutionary perspective,

there's no selective pressure for the virus

to become more virulent over time.

When I say virulent, I mean,

I tend to attempt disease severity.

There is always a selective pressure for the virus

to become more transmissible over time

because if you think about a virus as having goals

and ambitions, it's goal is just spread as much as possible.

But really, I would largely say that the case numbers

are reflective of lack of vaccination.

And so like I said, that's really the thing

that concerns me most about flu.

Kirsty Short, thank you so much for sharing

your lab notes with me.

My pleasure.

Professor Kirsty Short is a virologist

at the University of Queensland.

And if you take nothing else away

from this episode of lab notes,

this year's flu shot will be available

nationally from April.

This episode of lab notes was made on the lands

of the Gadigal and Manang Nungar people.

It was produced by Fiona Pepper

and mixed by Tim Jenkins.

I'm Jonathan Webb and I'll catch you next week.

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