Influenza Outbreak During Exercise Talisman Sabre, Queensland, Australia, July 2019.

Influenza appeared in Queensland, Australia during Exercise Talisman Sabre (TS-19) in July 2019 with an early focus within the New Zealand Defence Force members arriving in Australia aboard HMNZS Canterbury. A total of 76 cases of influenza-like illness (ILI) were reported, of which 43 were confirmed by rapid diagnostic tests to be influenza A (n=32) and B (n=11). Australia's influenza season (starting in March, peaked in July 2019) exposed large numbers of military members to a virus for which they had been suboptimally immunized either because of low uptake of the Southern Hemisphere vaccine by Australians/New Zealanders who were not mandated to be immunized, or because U.S. soldiers had received only the Northern Hemisphere vaccine for the 2018-2019 season. A low-intensity clinical unit separate from the main exercise was used as a means of isolating ILI cases both to facilitate their treatment and limit disease spread. Despite disease rates of <1%, influenza still had a major impact on TS-19 mostly in terms of the considerable medical resources required to manage ILI.