Avian influenza subtype A(HxNy) viruses are zoonotic and may occasionally infect humans through direct or indirect contact, resulting in mild to severe illness and death. Member States in the Western Pacific Region (WPR) communicate and notify the World Health Organization of any human cases of A(HxNy) through the International Health Regulations (IHR 2005) mechanism. This report includes all notifications in the WPR with illness onset dates from 1 November 2003 to 31 July 2022. During this period, there were 1972 human infections with nine different A(HxNy) subtypes notified in the WPR. Since the last report, an additional 134 human avian influenza infections were notified from 1 October 2017 to 31 July 2022. In recent years there has been a change in the primary subtypes and frequency of reports of human A(HxNy) in the region, with a reduction of A(H7N9) and A(H5N1), and conversely an increase of A(H5N6) and A(H9N2). Furthermore, three new subtypes A(H7N4), A(H10N3) and A(H3N8) notified from the People’s Republic of China were the first ever recorded globally. The public health risk from known A(HxNy) viruses remains low as there is no evidence of person-to-person transmission. However, the observed changes in A(HxNy) trends reinforce the need for effective and rapid identification to mitigate the threat of a pandemic from avian influenza if person-to-person transmission were to occur.

The establishment of enhanced surveillance systems for mass gatherings to detect infectious diseases that may be imported during an event is recommended. The World Health Organization Regional Office for the Western Pacific contributed to enhanced event-based surveillance for the Tokyo 2020 Olympic and Paralympic Games (the Games) by using Epidemic Intelligence from Open Sources (EIOS) to detect potential imported diseases and report them to the National Institute of Infectious Diseases (NIID), Japan. Daily screening of media articles on global infectious diseases was conducted using EIOS, which were systematically assessed to determine the likelihood of disease importation, spread and significant impact to Japan during the Games. Over 81 days of surveillance, 103 830 articles were screened by EIOS, of which 5441 (5.2%) met the selection criteria for initial assessment, with 587 (0.6%) assessed as signals and reported to NIID. None of the signals were considered to pose a significant risk to the Games based on three risk assessment criteria. While EIOS successfully captured media articles on infectious diseases with a likelihood of importation to and spread in Japan, a significant manual effort was required to assess the articles for duplicates and against the risk assessment criteria. Continued improvement of artificial intelligence is recommended to reduce this effort.