World

Tue Jul 22

How these common viruses are tracking this winter – and how to protect yourself

Written by: Adrian Esterman, Professor of Biostatistics and Epidemiology, University of South Australia

Winter is here, and with it come higher rates of respiratory illnesses. If you’ve been struck down recently with a sore throat, runny nose and a cough, or perhaps even a fever, you’re not alone.

Last week, non-urgent surgeries ^[1] were paused in several Queensland hospitals due to a surge of influenza and COVID cases filling up hospital beds.

Meanwhile, more than 200 aged care facilities ^[2] around Australia are reportedly facing COVID outbreaks.

So, just how bad are respiratory infections this year, and which viruses are causing the biggest problems?

COVID

Until May, COVID case numbers were about half last year’s level ^[3], but June’s 32,348 notifications are closing the gap (compared with 45,634 in June 2024). That said, we know far fewer people test now than they did earlier in the pandemic, so these numbers are likely to be an underestimate.

According to the latest Australian Respiratory Surveillance Report ^[4], Australia now appears to be emerging from a winter wave of COVID cases driven largely by the NB.1.8.1 subvariant ^[5], known as “Nimbus”.

Besides classic cold-like symptoms, this Omicron offshoot ^[6] can reportedly cause particularly painful sore throats as well as gastrointestinal symptoms such as nausea and diarrhoea.

While some people who catch COVID have no symptoms or just mild ones, for many people the virus can be serious. Older adults and those with chronic health issues remain at greatest risk of experiencing severe illness and dying from COVID ^[7].

Some 138 aged care residents ^[8] have died from COVID since the beginning of June.

The COVID booster currently available is based on the JN.1 subvariant ^[9]. Nimbus is a direct descendant of JN.1 – as is another subvariant in circulation, XFG or “Stratus”^[10] – which means the vaccine should remain effective against current variants.

Free boosters are available to most people annually, while those aged 75 and older ^[11] are advised to get one every six months.

Vaccination ^[12], as well as early treatment with antivirals ^[13], lowers the risk of severe illness and long COVID ^[14]. People aged 70 and older, as well as younger people with certain risk factors, are eligible for antivirals ^[15] if they test positive.

Influenza

The 2025 flu season has been unusually severe ^[16]. From January to May, total case numbers were 30% higher than last year ^[17], increasing pressure on health systems.

More recent case numbers seem to be trending lower than 2024, however we don’t appear to have reached the peak yet ^[18].

Flu symptoms ^[19] are generally more severe than the common cold and may include high fever, chills, muscle aches, fatigue, sore throat and a runny or blocked nose.

Most people recover in under a week ^[20], but the flu can be more severe (and even fatal) in groups including older people, young children and pregnant women.

An annual vaccination is available for free ^[21] to children aged 6 months to 4 years, pregnant women, those aged 65+, and other higher-risk groups.

Queensland ^[22] and Western Australia ^[23] provide a free flu vaccine for all people aged 6 months and older, but in other states and territories, people not eligible for a free vaccine can pay (usually A$30 or less) to receive one.

RSV

The third significant respiratory virus, respiratory syncytial virus ^[24] (RSV), only became a notifiable disease in 2021 (before this doctors didn’t need to record infections, meaning data is sparse).

Last year saw Australia’s highest case numbers ^[25] since RSV reporting began. By May, cases in 2025 were lower than 2024, but by June, they had caught up: 27,243 cases this June versus 26,596 in June 2024. However it looks as though we may have just passed the peak ^[26].

RSV’s symptoms are usually mild and cold-like, but it can cause serious illness such as bronchiolitis and pneumonia. Infants, older people, and people with chronic health conditions are among those at highest risk ^[27]. In young children, RSV is a leading cause ^[28] of hospitalisation.

A free vaccine ^[29] is now available for pregnant women, protecting infants for up to six months. A monoclonal antibody (different to a vaccine but also given as an injection) is also available for at-risk children up to age two, especially if their mothers didn’t receive the RSV vaccine during pregnancy.

For older adults ^[30], two RSV vaccines (Arexvy and Abrysvo) are available, with a single dose recommended for everyone aged 75+, those over 60 at higher risk due to medical conditions, and all Aboriginal and Torres Strait Islander people aged 60+.

Unfortunately, these are not currently subsidised and cost about $300 ^[31]. Protection ^[32] lasts at least three years.

The common cold

While viruses including COVID, RSV and influenza dominate headlines, we often overlook one of the most widespread – the common cold.

The common cold can be caused by more than 200 different viruses ^[33] – mainly rhinoviruses but also some coronaviruses, adenoviruses and enteroviruses.

Typical symptoms include ^[34] a runny or blocked nose, sore throat, coughing, sneezing, headache, tiredness and sometimes a mild fever.

Children get about 6–8 colds per year ^[35] while adults average 2–4, and symptoms usually resolve in a week. Most recover with rest, fluids, and possibly over-the-counter medications.

Because so many different viruses cause the common cold, and because these constantly mutate, developing a vaccine ^[36] has been extremely challenging. Researchers continue to explore solutions, but a universal cold vaccine remains elusive.

How do I protect myself and others?

The precautions we learned during the COVID pandemic remain valid. These are all airborne viruses which can be spread ^[37] by coughing, sneezing and touching contaminated surfaces.

Practise good hygiene, teach children proper cough etiquette, wear a high-quality mask if you’re at high risk, and stay home to rest if unwell.

You can now buy rapid antigen tests (called panel tests) that test for influenza (A or B), COVID and RSV. So, if you’re unwell with a respiratory infection, consider testing yourself at home.

While many winter lurgies can be trivial, this is not always the case. We can all do our bit to reduce the impact.