Australia is heading into the holiday season with flu levels that look more like winter than early summer. After a record-breaking flu year, major eastern states are now reporting case numbers that keep climbing instead of easing off. Health authorities link this pattern to a new version of influenza A H3N2 that has appeared worldwide and is now circulating locally, arriving on the back of a severe northern hemisphere flu season.
Officials say this mutated H3N2 “subclade K” strain is behind a sharp spike in infections and hospital admissions. Nationally, flu notifications have already hit about 478,000 cases by early December, almost 30% higher than the previous record of 365,000 set in 2024. One state logged nearly 4,000 cases in the week ending 7 December, compared with just over 400 in the same week last year, an increase of more than 800%. Teenagers aged 10 to 19 appear to be the hardest hit in some areas and densely populated regions in western parts of major cities report the highest numbers.
The impact is showing up in mortality data as well. Figures from the national statistics agency indicate around 1,385 deaths linked to influenza by October, roughly a 32% jump on the 1,045 deaths recorded for all of 2024. Globally, the picture looks similar. Health systems in the northern hemisphere have already struggled through a bad flu season, with countries such as the United Kingdom preparing for thousands of hospitalisations and some hospitals reintroducing measures like mandatory masking for staff and patients, even as governments stop short of enforcing mask rules on the general public.
Vaccination remains the main line of defence but coverage seems to be slipping at the worst possible time. Data from the national immunisation research centre show that by September only about 60.5% of people over 65 and 25.7% of children aged six months to five years had been vaccinated against flu, even though these age groups face the highest risk of severe disease. During the COVID-19 years, uptake for these groups was noticeably higher, around 8 percentage points more for older adults and about 19 percentage points more for young children, which suggests that a sense of urgency has faded just as this new strain spreads.
Looking ahead to Christmas and the summer travel rush, health agencies are urging people to update their flu shots, reconsider mask use in crowded indoor spaces and stay home if they feel unwell. The new H3N2 variant seems set to test how well communities balance festive plans with basic precautions. If vaccination momentum does not improve and people ignore early symptoms, this off-season wave could prolong pressure on hospitals and turn what should be a relaxed holiday period into another reminder that respiratory viruses do not always follow the calendar.
