Many Australians have stopped worrying about respiratory viruses. The pandemic has passed and attention has shifted. COVID no longer dominates the headlines, and influenza is often dismissed as a routine winter illness.

But the latest provisional figures from the Australian Bureau of Statistics (ABS) suggest otherwise.

In 2025, there were 1,455 deaths in Australia due to influenza. This is the highest number the ABS has recorded in this series of data in modern times. This is more than in previous peak years, such as 2017 (1,276 deaths) and 2019 (1,072 deaths).

COVID continued its long decline as a cause of death. In 2025, there were 1,718 deaths due to COVID, down from 3,908 in 2024 and 4,613 in 2023.

These figures count deaths directly attributed to each virus.

The charts below also include deaths where the virus contributed but was not the main cause.

More importantly, between August 2025 and January 2026, influenza was the underlying cause of more deaths each month than COVID, a pattern we have not seen since the pandemic began.

None of this means COVID has disappeared. Far from it. But it means the mix of respiratory viruses is changing.

There’s also a third respiratory virus that often gets overlooked – respiratory syncytial virus, or RSV.

Looking beyond case numbers

When people hear reports that a respiratory virus season is “bad”, they often think about case numbers, meaning the number of people testing positive for a particular disease.

But case numbers have become increasingly unreliable. Most people with a cough, sore throat or fever don’t get tested. Many never see a doctor. Even when they do, they aren’t always tested. And if they are, no test is 100% accurate.

That’s why epidemiologists often pay more attention to severe outcomes such as hospital admissions and deaths. Hospital admissions are generally a better measure than case notifications, but at the moment not all Australian states and territories report them consistently. That leaves deaths as the most reliable measure for comparing the impact of respiratory viruses over time.

The ABS data show that deaths caused by COVID have steadily fallen over the past three years, while deaths caused by influenza have moved in the opposite direction.

In 2024, influenza was recorded as the underlying cause of death in 807 Australians. Last year that almost doubled to 1,455. A big jump like that is unusual for a virus for which we have had vaccines for decades.

Influenza vs COVID deaths

One reason influenza appears to be doing so much damage is what we’re comparing it to – COVID – has become less deadly in recent years. Population immunity from vaccination and prior infection has substantially reduced the risk of severe disease.

COVID treatments are also available for people at high risk of severe disease, and hospital staff now have better ways of treating those severely ill.

Influenza behaves quite differently. The virus evolves rapidly, and vaccine effectiveness varies from year to year. As a result, immunity from last year’s infection or vaccination doesn’t necessarily provide much protection against this year’s strains. That is why a new influenza vaccine is needed every year. Some years influenza causes relatively little severe disease. Other years are much worse.

In 2025, we saw one of those years. A late-emerging H3N2 subclade K influenza variant (known as super K) extended the season and was poorly matched to the H3N2 strain in that year’s vaccine.

At the same time, influenza vaccine coverage among Australians aged 65 years and over was around 62%. This is down from 64% in 2023 and well short of the World Health Organization target of 75% for this age group.

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Read more: Can I get a free flu shot? And will it cover ‘super K’? Your influenza vaccine questions answered

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Then there’s RSV

Lost in the discussion about flu and COVID is RSV. This is best known as a cause of illness in babies and young children. But older people can also become seriously ill.

In 2025, RSV was the underlying cause of 198 deaths in Australia. However, RSV is often recorded as a contributing rather than underlying cause of death because it can worsen conditions such as chronic lung disease or heart failure. In 2025, another 392 deaths listed RSV as a contributor.

Taken together, this points to RSV playing a much larger role in respiratory deaths – by both contributing to, and being the underlying cause of, death.

What does this mean for winter?

So, will 2026 be another severe flu year? We don’t yet know. What is clear, though, is all three viruses are circulating side by side, and any one of them could surge.

Early data suggest influenza deaths during January and February were roughly double those recorded during the same period in 2025. However, these figures can fluctuate considerably early in the year, so it is too soon to draw firm conclusions.

COVID deaths remain at relatively low levels, while RSV continues to circulate in the background.

Older Australians remain at greatest risk of death from all three viruses.

So vaccination still matters. People aged 65 years and over, aged-care residents, people with chronic health conditions, Aboriginal and Torres Strait Islander people, pregnant women and young children should be up to date with recommended vaccines.

The 2026 flu vaccine has been updated to better match last year’s troublesome H3N2 strain. Importantly, influenza, COVID and RSV vaccines can all be given at the same visit.

Adrian Esterman receives funding from NHMRC, MRFF and ARC.

The MV Hondius, a Dutch cruise ship with a deadly outbreak of hantavirus, was on its way to the Canary Islands on May 7, 2026, after evacuating three ill passengers for treatment.

The World Health Organization confirmed the outbreak on May 4, noting a total of seven infections, with three deaths since the outbreak began in early April. An eighth case was confirmed on May 6.

Because of the illness’s one- to eight-week incubation period, additional cases may still be identified. Health officials around the world are monitoring passengers who disembarked from the ship in the early days of the outbreak in late April. Health officials emphasize, however, that the risk to the public from the outbreak is low.

I’m a medical epidemiologist – here’s what you need to know about the virus and how the outbreak is playing out.

What is hantavirus?

Hantavirus isn’t just one virus but a group of closely related viruses found throughout the world. Their natural reservoir is rodents, such as wild mice, rats and moles. Infected rodents don’t get symptoms, but the virus replicates in their cells. It sometimes spills over into other animals, including humans, and can cause severe disease and even death.

There are two general types of hantaviruses. Old World hantaviruses, typically found in Europe and Asia, generally affect the kidneys. Their mortality rate in people is 15% or less.

New World hantaviruses, such as the one causing the outbreak on the Hondius, occur in North and South America. The best-known strains of this type are the Andes virus, the strain that was confirmed in the cruise ship outbreak, and the Sin Nombre virus, which likely caused the death of Betsy Arakawa, Gene Hackman’s wife, in March 2025.

These viruses generally affect the lungs and are fatal in about 40% of cases. Symptoms start with a flu-like illness and can progress quickly to intense inflammation in the lungs that leads to lung and heart failure.

A person with a hantavirus infection may experience symptoms anywhere from a week to eight weeks after exposure. There is no treatment; doctors can offer only supportive care, such as hydration, artificial respiration or dialysis.

How do these viruses spread?

Cases of hantavirus infection are rare. The Centers for Disease Control and Prevention recorded 890 cases in the U.S. from 1993, when surveillance began, through the end of 2023.

The vast majority of cases occur in China, with thousands of cases caused by Old World hantavirus strains occurring annually.

Most often, people become infected with these viruses by inhaling aerosolized urine or droppings from infected rodents. Imagine a cabin infested with mice infected by the virus – sweeping the cabin would shake up dust from the mouse urine and droppings, distributing it through the air and enabling people to inhale the viral particles. There’s a smaller risk of getting ill through direct contact, such as by being bitten by an infected rodent or by touching its saliva.

The worry on the cruise ship is human-to-human transmission. Epidemiologists had previously found hints that the Andes virus may be transmitted from one person to another under certain circumstances, such as close, sustained contact in close quarters, like a small cruise ship.

What do investigators think happened on the cruise ship?

The Hondius, now carrying close to 150 passengers, started out in Argentina on April 1 and was sailing north on a 33-day journey.

There were no reports of rodents on the ship, so it’s unlikely the illness started there. According to news reports, the people who first got sick had been touring Argentina and Chile for months beforehand. Researchers speculate they likely got infected during an activity in which they were exposed to a rodent carrying the disease or its excrement.

Given these viruses’ weekslong incubation period, these people may have been feeling fine when they boarded the ship, before eventually falling ill. They may have then spread Andes virus to others through breathing shared air or other close contact in close quarters.

What happens now?

The ship is now traveling to Spain, and multiple patients are being evacuated along the way.

Also, researchers are tracking 29 people who disembarked from the ship on April 24, before the outbreak was identified. People who had significant exposure will likely be quarantined to watch for symptoms and be isolated if symptoms develop.

Residents of three U.S. states are being monitored. Dutch officials announced on May 7 that a flight attendant who was not a passenger but briefly interacted with a passenger was hospitalized with possible hantavirus symptoms.

Is the situation dangerous?

Health officials can’t rule out that additional hantavirus cases may emerge in the cruise ship outbreak, but beyond the ship the risk remains low. That’s because most cases of hantavirus, including Andes virus, are acquired directly from rodents or their excrement and not from other humans.

It’s important to note, however, that even on vacation, people should pay attention to risks for infection – particularly as they may be very different from the ones they’re used to at home.

Daniel Pastula does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.