Novel influenza A denotes infection by an influenza A virus of non-human origin (typically avian or swine) that has crossed into human populations and may be adapting toward sustained human-to-human transmission [1]. Such a virus becomes capable of initiating an influenza pandemic when it achieves efficient replication and transmissibility within the new human host [1].
Disease overview
Novel influenza A
人感染新亚型流感
Evidence-backed informationEN 5/7 applicable sections · ZH 5/7 applicable sectionsUpdated Sep 3, 2026
Novel influenza A refers to zoonotic infections with non-human-origin influenza A viruses that have acquired or threaten to acquire the capacity for efficient human-to-human transmission, representing the antecedent stage of pandemic emergence [1]. These infections occur sporadically through cross-species transmission from avian or swine reservoirs and pose persistent pandemic threats [2]. The viruses originate from antigenically diverse wild aquatic bird populations, where infection is typically asymptomatic, but may adapt to human hosts through species-specific molecular interactions governing tropism and transmission [1].
Read the full clinical and epidemiological profile6
The clinical presentation of zoonotic and early-pandemic novel influenza A infections generally resembles that of seasonal influenza, with abrupt onset of respiratory symptoms and myalgia, with or without fever, and most patients recovering within approximately one week; however, some individuals may experience severe or fatal complications [2].
Novel influenza A infections occur sporadically as zoonotic spillover events from animal reservoirs rather than as sustained seasonal circulation, and the global burden of seasonal influenza (caused by influenza A and B) declined markedly in 2020–21 following the emergence of SARS-CoV-2 and partially rebounded in 2021–22 [2]. The vast antigenic reservoir of influenza A in wild aquatic birds provides an ongoing source of sporadic zoonotic introductions of avian or swine origin, each of which constitutes a potential pandemic threat [2].
Sporadic zoonotic transmission occurs when avian or swine influenza A viruses cross species barriers from animal reservoirs into humans; pandemic emergence requires that a virus acquire sufficient adaptive mutations to support stable human-to-human transmission [1]. The transition is governed by species-specific virus–host cell interactions that determine tropism, including binding, entry, nuclear replication, assembly, and release of virions [1].
Prevention of novel influenza A relies on broad seasonal influenza vaccination programmes to reduce the burden of circulating influenza viruses and on continued vigilance for zoonotic spillover events that could seed a pandemic [2]. The development of next-generation vaccines with improved effectiveness, together with targeted antivirals and therapeutic agents informed by an understanding of viral tropism, is a central component of preparedness against emerging novel influenza A strains [1][2].
- 1AbuBakar U et al. Avian Influenza Virus Tropism in Humans. Viruses. 2023 Mar 24. PMID: 37112812. doi: 10.3390/v15040833.PubMed: https://pubmed.ncbi.nlm.nih.gov/37112812/
- 2Uyeki TM et al. Influenza. Lancet. 2022 Aug 27. PMID: 36030813. doi: 10.1016/S0140-6736(22)00982-5.PubMed: https://pubmed.ncbi.nlm.nih.gov/36030813/
- J09
- 1E30.0
Coverage
Reporting countries and regions
Trends by reporting country
Monthly patterns over time
Research Radar
Recent related research
Influenza Activity and Composition of the 2022–23 Influenza Vaccine — United States, 2021–22 Season
MMWR. Morbidity and Mortality Weekly Report
Pandemic Potential of a Strain of Influenza A (H1N1): Early Findings
Science
Literature links are provided for discovery and do not alter or validate the surveillance series above.
Data access
Page dataset index with source links and update metadata.
Official sourcesAuthority, cadence, notes21
Australia NINDSS
Australia
Australian national notifiable diseases surveillance dashboard.
Australia NINDSS — Australian Capital Territory
Australian Capital Territory, Australia
Australian NINDSS monthly state/territory notifications for Australian Capital Territory, kept separate from the Australia national aggregate.
Australia NINDSS — New South Wales
New South Wales, Australia
Australian NINDSS monthly state/territory notifications for New South Wales, kept separate from the Australia national aggregate.
Australia NINDSS — Northern Territory
Northern Territory, Australia
Australian NINDSS monthly state/territory notifications for Northern Territory, kept separate from the Australia national aggregate.
Australia NINDSS — Queensland
Queensland, Australia
Australian NINDSS monthly state/territory notifications for Queensland, kept separate from the Australia national aggregate.
Australia NINDSS — South Australia
South Australia, Australia
Australian NINDSS monthly state/territory notifications for South Australia, kept separate from the Australia national aggregate.
Australia NINDSS — Tasmania
Tasmania, Australia
Australian NINDSS monthly state/territory notifications for Tasmania, kept separate from the Australia national aggregate.
Australia NINDSS — Victoria
Victoria, Australia
Australian NINDSS monthly state/territory notifications for Victoria, kept separate from the Australia national aggregate.
Australia NINDSS — Western Australia
Western Australia, Australia
Australian NINDSS monthly state/territory notifications for Western Australia, kept separate from the Australia national aggregate.
China CDC Weekly
China
Monthly notifiable infectious disease reports published by China CDC.
National Disease Control and Prevention Administration
China
Official China public health bulletin and query portal.
PubMed
China
Biomedical literature discovery feed used as supplementary context.
Hong Kong, China CHP Notifiable Diseases
Hong Kong, China
Hong Kong, China CHP annual notifiable infectious disease CSVs normalized to national monthly totals
JP NIID Weekly
Japan
Japan weekly infectious disease surveillance via NIID/JIHS.
Korea KDCA EID
South Korea
Korea KDCA notifiable infectious disease OpenAPI or portal/KOSIS downloads aggregated to national monthly notification counts.
Norway FHI MSIS Statistics Bank
Norway
Norway FHI MSIS national monthly notifications from the official Allvis frontend API; adapter contract checks guard the unversioned endpoint.
New Zealand PHF Science Monthly Notifiable Diseases
New Zealand
PHF Science (formerly ESR) monthly notifiable disease surveillance data via internal globalID2 crawler
Singapore CDA Weekly Infectious Diseases Bulletin
Singapore
Singapore national weekly case notifications, combining the official data.gov.sg 2012–2022 CSV history with CDA annual workbooks from 2023 onward; 2023 weekly PDFs are retained as a source fallback.
Taiwan, China CDC NIDSS
Taiwan, China
Taiwan, China monthly notifiable infectious disease open-data CSV feed.
US CDC NNDSS
United States
CDC National Notifiable Diseases Surveillance System provisional data.
US CDC NHSS HIV
United States
CDC NNDSS weekly data plus NHSS annual national HIV diagnoses