No Evidence of HPAI H5N1 in Coastal Areas of Australia's Antarctic Territory During the 2025/26 Austral Summer

High pathogenicity avian influenza (HPAI) H5N1 clade 2.3.4.4b (hereafter HPAI H5N1) is the cause of a globally devastating animal pandemic (panzootic).Since 2020, HPAI H5N1 has had a substantial range expansion and has now been detected on every continent [1,2].In the Antarctic region, the virus was first identified in the sub-Antarctic (South Georgia Island) in October 2023, with the first confirmed detection in the Antarctic Treaty Area (ATA) occurring on the Antarctic Peninsula a few months later.HPAI H5N1 reoccurred in this region in the austral summer of 2024/2025 and 2025/2026 [3].Considerable expansion of HPAI H5N1 in the sub-Antarctic occurred by the austral summer of 2024/2025 with detections on Gough Island, Marion Island, Kerguelen Island and Crozet Islands [3,4].In the 2025 austral spring, the virus was also detected on Australia's sub-Antarctic Heard Island [5], and in June 2026, this same lineage was confirmed in Australia [1].To date, spread beyond the Antarctic Peninsula to other parts of continental Antarctica has not been observed.