Cases of the flu are spiking around Australia after the virus was forced underground for two years thanks to tight Covid-19 restrictions.
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Now the borders are open, restrictions have eased drastically and an expert says cases have gone from "zero to full-on".
Figures from the federal government suggest cases started climbing weeks ago. And a rapid 130 per cent jump in flu cases early in the season prompted Queensland authorities to offer people free vaccine jabs.
High cases in NSW have authorities thinking of doing the same.
All of this is happening while Australia records roughly 40,000 Covid-19 cases per day.
Click here for New Zealand's Covid-19 advice
So, how do I know if I have Covid-19 or the flu?
It's really, really hard to know the difference from symptoms alone without a designated flu test. That's because the symptoms are so similar.
With the exception of the loss of taste and smell in the case of Covid-19, the symptoms of the two are very similar.
"It's hard to know without a lab or good-quality test to know what that virus might be," says University of Queensland virologist Ian Mackay.
"Flu has a muscle stiffness thing as well, headaches or a cough, it's really hard to differentiate one from the other without some sort of test."
How dangerous is the flu?
The rapid increase in flu cases appears to have cast influenza in a different light.
It's a highly transmissible respiratory disease that has the potential to cause serious harm. Sound familiar?
Dr Mackay says a good way to think about it is to not get too far into the weeds about it all.
"When you look at crude numbers, most of the time SARS-CoV-2 is not going to kill you and most of the time influenza is not going to kill you, and it's not going to put you in ICU but sometimes it will," he said.
"A large proportion of Australians have a condition that can be exacerbated by the flu.
"You don't know beforehand if that's going to happen to you, to your child or your grandparent."
What precautions should I take then?
This is where masks and physical distancing come in. "Most obviously we've got this new measure which we didn't really use much before the pandemic and that's masks," Dr Mackay said.
"That can help reduce our chances of getting infected and having it transmit to us."
That's because Covid-19 and the flu spread in very similar ways.
"These are airborne viruses - and by airborne I mean they're not just droplets that require you to be close-range, if you like, for anything to be coughed onto you.
"They [the virus] float around in clouds and the viruses can stay infectious in those aerosols for some time and you can breathe them in.
"It's important to remember we're not talking about different transmission routes here, there's no need to differentiate, we can treat them in similar ways."
And if you're feeling unwell, stay home. "I've seen people at various workplaces coming in sick. We don't need to keep doing that, we need to understand our lives and illnesses impact others," Dr Mackay said.
"Stay home, if that's at all possible. If that's not possible, please get a well-fitting mask."
Should I get the flu vaccine?
For all their similarities, Covid-19 and the flu require different vaccines.
And while there's been a huge push to get the country vaccinated against Covid-19, so-called "vaccine exhaustion" has been a concern as healthcare workers urge people to get vaccinated against the flu.
With an election campaign, a war raging in Ukraine and cost of living rising, Covid-19 has dropped off the radar for some Australians. But experts say the number of daily cases and deaths is "extraordinary".
"We have different vaccines for the two viruses," Dr Mackay said.
"We're pretty well-vaccinated for Covid-19 in this country, that's really great but we're often not well-vaccinated, as we often aren't, for influenza.
"That will need to change because with flu ripping through communities now at such a challenging pace, it's going to be important to try and prevent severe disease and we can do that."
He says not being vaccinated is one of the biggest risks when it comes to the flu.
"The biggest risk is that we're not really well-vaccinated because we didn't really see much flu last year, or any flu the year before because of lockdown, " he said.
"We don't really have that vaccine immunity in our youngest children and they can be some of the most likely to end up in hospital because of the flu."
Cases of the flu are climbing fast
Usually, there's a gradual increase in flu cases over the cooler months. But that doesn't seem to be the case this year.
Dr Mackay says we're experiencing a spike in cases early in the year.
"Some of that is due to increased lab capacity for flu testing, but the rate itself - or the amount of positives per number of samples tested - suggests a spike as well," he said.
"We usually see a bit of a baseline, the foothills of the mountain if you like, as the season comes into play.
"But this time we've gone from zero to full-on and it's not clear how high this peak will be, nor how long the flu season will last.
"So if you're looking to get vaccinated, now's the time to get it."
- ABC