ETIDIOH - NEW

  Abstract Influenza A viruses exhibit broad host tropism, infecting multiple species including humans, avian species, and swine. Swine influenza virus (SIV), while primarily circulating in porcine populations , demonstrates zoonotic potential with sporadic human infections . In this investigation, we identified two H1N1 subtype swine influenza A virus strains designated A/swine/China/SD6591/2019(H1N1) (abbreviated SD6591) and A/swine/China/SD6592/2019(H1N1) (abbreviated SD6592) in Shandong Province , China. The GenBank accession numbers of the SD6591 viral gene segments are PV464931-PV464938, and the GenBank accession numbers corresponding to each of the eight SD6592 viral gene segments are PV464939-PV464946. Phylogenetic and recombination analyses suggest potential evolutionary differences between the isolates. SD6591 displayed a unique triple-reassortant genotype : comparative nucleotide homology assessments demonstrated that the PB2, PB1, NP, NA, HA, and NEP genes shared the hi...

  Abstract In a new study, Zhao et al. (2025) obtain 959 whole genome sequences of H1N1 subtype swine influenza virus (SIV) isolated from China . Their analysis of the sequences , isolated between 1977 and 2020, reveals how H1N1 lineages have co-evolved and contributed to instances of zoonotic transmission within the region. This study’s findings characterize the long-term evolutionary effects of frequent viral reassortment in SIV and highlight its potential to drive future pandemics. Source:  Link:  https://academic.oup.com/evolut/advance-article/doi/10.1093/evolut/qpaf262/8400336 ____

  Influenza at the human-animal interface  Summary and risk assessment, from 6 November to 19 December 2025 {1} -- New human cases {1,2}:  - From 6 November to 19 December 2025, based on reporting date , the detection of influenza A( H5N1 ) in one human , A( H5N5 ) in one human , A( H9N2 ) in seven humans , and an influenza A( H1N1 ) variant virus in one human were reported officially.  - In addition , one human case of infection with an influenza A( H1N2 ) variant virus was detected.  -- Circulation of influenza viruses with zoonotic potential in animals :  - High pathogenicity avian influenza (HPAI) events in poultry and non-poultry animal species continue to be reported to the World Organisation for Animal Health (WOAH).{3}  - The Food and Agriculture Organization of the United Nations (FAO) also provides a global update on avian influenza viruses with pandemic potential.{4}  - Additionally, low pathogenicity avian influenza viruses as well a...

  Abstract I nterspecies transmission of human influenza A viruses (FLUAV) to swine occurs frequently, yet the molecular factors driving adaptation remain poorly understood . Here we investigated how vaccine-induced immunity shapes the evolution of a human-origin H3N2 virus in pigs using an in vivo sustained transmission model . Pigs (seeders) were vaccinated with a commercial inactivated swine vaccine and then infected with an antigenically distinct FLUAV containing human-origin HA/NA . Contact pigs were introduced two days later. After 3 days, seeder pigs were removed, and new contacts introduced. This was repeated for a total of 4 contacts. Sequencing of nasal swab samples showed the emergence of mutations clustered near the HA receptor binding site , enabling immune escape and abolishing binding to N-glycolylneuraminic acid. Mutant viruses recognized α2,6-sialosides with 3 N-acetyllactosamine repeats , which are rare in swine lungs, while the parental virus bound structures wit...

  {Excerpt} Novel Influenza A Virus Infections Two confirmed human infections with novel influenza A viruses were reported to CDC this week .  One infection with an influenza A(H5N5) virus was reported by the Washington State Department of Health and one infection with an influenza A(H1N2) variant (A(H1N2)v) virus was reported by the Vermont Department of Health. One infection with an influenza A(H5N5) virus was reported by the Washington State Department of Public Health .  -- The case occurred in an individual aged ≥18 years .  -- This individual developed symptoms during the week ending October 25 , 2025 (Week 43) and was hospitalized with their illness during the week ending November 8, 2025 (Week 45).  -- Respiratory specimens collected at the healthcare facility tested positive for influenza A and were presumptive positive for influenza A(H5) at the University of Washington.  -- The specimens were sent to the Washington State Public Health Laboratory ...

  September 2025   The development of influenza candidate vaccine viruses (CVVs), coordinated by WHO, remains an essential component of the overall global strategy for influenza pandemic preparedness . Selection and development of CVVs are the first steps towards timely vaccine production and do not imply a recommendation for initiating manufacture . National authorities may consider the use of one or more of these CVVs for pilot lot vaccine production , clinical trials and other pandemic preparedness purposes based on their assessment of public health risk and need.  Zoonotic influenza viruses continue to be identified and evolve both antigenically and genetically, leading to the need for additional CVVs for pandemic preparedness purposes.  Changes in the antigenic and genetic characteristics of these viruses relative to existing CVVs and their potential risks to public health justify the need to develop new CVVs. This document summarizes the antigenic and genetic c...

  New human cases {1,2}:  -- From 26 August to 29 September 2025 , based on reporting date, the detection of influenza A(H5) in one human , influenza A(H5N1) in one human , influenza A(H9N2) in eight humans and an influenza A(H1N1) variant ((H1N1)v) virus in one human were reported officially.   Circulation of influenza viruses with zoonotic potential in animals :  -- High pathogenicity avian influenza (HPAI) events in poultry and non-poultry animal species continue to be reported to the World Organisation for Animal Health (WOAH).{3}  -- The Food and Agriculture Organization of the United Nations (FAO) also provides a global update on avian influenza viruses with pandemic potential.{4}  Risk assessment {5}:  -- Sustained human to human transmission has not been reported from these events.  -- Based on information available at the time of this risk assessment update , the overall public health risk from currently known influenza A viruses d...