No peak: Australia bucks a years-long winter sickness trend

Australia appears to have avoided the winter surge in COVID-19 cases seen in previous years, with experts pointing to changing virus behaviour and population immunity as possible explanations.

Federal surveillance data shows 64,357 COVID-19 cases have been reported so far this year, 56 per cent fewer than the 146,232 cases recorded over the same period in 2025.

The latest figures paint an unusual picture of Australia's COVID-19 landscape, with infections remaining well below last year's levels even as cases begin to tick upwards across the community.

Where has the winter wave gone?

Professor Catherine Bennett, chair of epidemiology at Deakin University, said the absence of a clear winter peak was significant.

She said Australia's experience reflected a population that had gradually developed greater immunity to the virus through previous infections and vaccination.

"When you have variants that stay in circulation for a longer period of time, more people have had their immunity naturally boosted against that variant, and that then keeps infection rates down," she said.

Bennett said having fewer major changes in the variants circulating than earlier in the pandemic may be helping people's existing immunity provide greater protection against severe infection.

Rather than a substantially different variant emerging every few months in Australia, the same dominant variant was continuing to circulate, allowing immunity in the population to remain "primed".

Have COVID-19 patterns changed?

Epidemiologist professor Adrian Esterman told SBS News that the pattern of COVID-19 outbreaks had changed significantly over the past few years.

"We aren't actually seeing waves anymore, or if we do have waves they're very small ones," he said.

Esterman said smaller increases in cases now tended to coincide with the emergence of a variant that was better able to transmit or evade existing immunity.

The experts said that a major change to the virus's genetics could still trigger a larger wave, but said there was currently little evidence of one developing.

"Unless there's a huge genetic shift in the virus ... that's the only thing that could disrupt things and cause another wave," Esterman said.

Fewer cases detected

The sharp fall in reported cases raises the question of whether fewer Australians are getting COVID-19, or if fewer infections are being detected.

Reported COVID-19 cases are only a proportion of all infections, meaning surveillance data cannot capture every person who contracts the virus.

But Bennett said she believed the lack of a winter peak was broadly consistent with what was being seen in other measures of COVID-19 severity.

She pointed to hospitalisation data showing COVID-19 was now causing less severe disease among younger and healthier adults than earlier in the pandemic.

At the same time, she warned that there were still important gaps in Australia's understanding of the virus, particularly in relation to the longer-term consequences of infection.

Why immunity could be making a difference

Bennett said repeated exposure to COVID-19 may now be giving many people protection against severe illness without necessarily preventing them from becoming infected.

People may therefore experience very mild infections that are never detected, or fight off infections without becoming noticeably sick.

Bennett and Esterman told SBS News that if the same variants continue circulating, people who have previously encountered them may have enough immunity to prevent infections from producing the large rise in cases Australia has seen in previous winters.

"It's sort of keeping our immunity levels primed up naturally," Bennet said.

But she said that protection is not evenly distributed.

Bennett said older people and those who are immunocompromised may not develop the same strength of immune response from previous exposure, which is why vaccination remains important for those groups.

What happens as we head into spring?

According to the latest federal surveillance report, from the Australian Centre for Disease Control, COVID-19 cases have started increasing again over the past fortnight.

But neither expert believes the rise signals the start of another major wave.

Bennett said the increase needed to be watched, particularly for evidence of a new variant gaining a foothold.

She said a new variant could potentially produce a summer surge, but there was currently no strong trend suggesting that was happening.

Esterman similarly expects the virus to continue producing relatively small increases in cases rather than the large, distinct waves seen earlier in the pandemic.

Could this become the new normal?

The absence of a winter peak does not mean COVID-19 has disappeared, or that future winters will necessarily look the same.

Both experts said that while Australia's 2026 experience could represent an important shift in the way COVID-19 behaves as an endemic respiratory virus, a significant change in the virus could alter the current pattern.

Bennett said the combination of declining transmission, population immunity and a more stable virus had put Australia in a much stronger position than it was in the early years of the pandemic.

"It's very unusual but an important sign that our population-level immunity is still evolving and maturing and putting us in a much better position to cope with an endemic disease like COVID-19."

And if the current trend continues through the warmer months, she said Australia could be entering its quietest 12-month period of COVID-19 transmission in years.

"If we can get through summer without another wave, then that will be the best 12 months we've had for a long time with COVID-19."

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