More than 2,500 Australians caught a new, easily spreading flu strain called Super-K right at the start of 2026. Health officials are worried this could be the worst flu year since 35 years of tracking began. Last year, over 500,000 Australians got flu, and 1,508 died, which was a jump from 2024. The Super-K strain, a mutation of Influenza A (H3N2), was first found in September by Melbourne's Peter Doherty Institute. This version spreads quickly but does not cause more severe illness, according to health authorities. Vaccines still protect well against serious sickness. Super-K is now in more than 30 countries. In Australia, 284 flu cases in the past week were children aged four and under. Professor Ian Barr said the virus likely started in small numbers in the US in mid-2025 and reached Australia in August. By November, flu cases rose in New South Wales, with emergency visits for flu-like illness hitting over 370 weekly. NSW reported over a third of Australia’s recent flu cases. Health Minister Ryan Park said many people might be sick but untested. Flu vaccination is dropping, especially among the most vulnerable. Only 25.7% of children under five got vaccinated last year—the lowest since 2021. Seniors over 65 had a 60.5% vaccine rate, a five-year low. The NSW Respiratory Surveillance Report showed over 3,000 confirmed flu cases weekly in December, rising 15% week by week during a time the flu usually slows down. Prof. Barr said, "It does seem to be a very fit virus," noting it spreads late in the season and continues to cause new cases. The Australian Health Protection Committee warned Super-K is not more severe, just faster at infecting people. However, its odd timing might strain hospitals during holidays. Travelers to the northern hemisphere are advised to get a flu shot. The Australian Centre for Disease Control said flu usually peaks in winter (June to September). They noted case numbers are unusually high for this time of year. Research from the EU shows current flu vaccines work better than expected against Super-K. They protect children 72.8% from hospital stays and adults 18-64 by 66.3%. Protection drops to 31.7% in those over 65. Prof. Barr said vaccination remains the best defense against Super-K.