ETIDIOH - NEW

  ABSTRACT Subtype H3N2 influenza A viruses (IAVs), which emerged in 1968 to cause a pandemic, have shown continual circulation and adaptation that has necessitated frequent updates of candidate vaccine viruses . Here, we sought to determine how genetic changes in the hemagglutinin (HA) and neuraminidase of 21 antigenically distinct H3N2 IAVs isolated from 1968 to 2019 correlate with mammalian fitness and adaptation. We found a surge of adaptation between 1997 and 2002 , resulting in the emergence of A/Fujian/411/2002 (H3N2) and poor vaccine efficacy , leading to an epidemic during the 2003–2004 season. This surge was characterized by a large reduction in binding to mammalian-type α2,6-linked sialic acids and increased infectivity and replication kinetics in humanized Madin-Darby canine kidney cells. HA glycosylation also increased most rapidly from 1968 to 2004 and then plateaued. Symptomatic infections were only evident in mice following inoculation with viruses isolated in the 1...

  ABSTRACT Systemic spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to extrapulmonary tissues has been observed following acute infections. Autopsy studies further indicate tissue-specific virus diversity, including in immune-privileged sites . Questions remain on the viral dynamics leading to the tissue tropism of SARS-CoV-2, including evolutionary trajectories and functional adaptations that could impact persistence and transmission . In this study, we characterized SARS-CoV-2 genomes from 27 distinct tissues collected from an autopsy case where the patient had a primary immune deficiency . We identified tissue-specific virus genotypes , in some instances coexisting within the same sites, with mutations primarily in the receptor-binding domain of the spike protein. Protein simulations and isolation of infectious virus indicate combinations of spike substitutions that would lead to increased protein stability and stronger binding of the virus to host cells. ...

  ABSTRACT An increase in the number of human cases of influenza A/H5N1 infection in the USA has raised concerns about the pandemic potential of the virus. Pre-existing population immunity is a key determinant for risk assessment and pandemic potential for any virus. Antibody responses against the bovine A/H5N1 hemagglutinin (HA) and neuraminidase (NA) proteins were measured among a population of influenza-vaccinated or influenza-infected individuals. Modest titers of bovine A/H5N1 HA-binding antibodies and low to undetectable neutralizing antibody titers were detected in a cohort of 73 individuals . Conversely, bovine A/H5N1 NA-binding and neuraminidase-inhibiting antibody titers were comparable to those against a human A/H1N1 NA at baseline . Seasonal influenza vaccination failed to significantly increase antibody titers against both HA and NA glycoproteins of bovine A/H5N1. Recent infection with human A/H1N1 but not A/H3N2 viruses induced significant increases in bovine A/H5N1-n...

  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...

  {By Subramanya CK - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=17954283 } Two Western Marsh Harrier wild birds in Burgas Region. Source: WOAH,  https://wahis.woah.org/#/in-review/6955 ____

  A fattening duck holding in Jász-Nagykun-Szolnok Region. Source: WOAH,  https://wahis.woah.org/#/in-review/6959 ____

A wild Mute Swan in Savinjska Region. Source: WOAH,  https://wahis.woah.org/#/in-review/6964 ____

{By  https://www.flickr.com/photos/sbern/ - https://www.flickr.com/photos/sbern/13471929904/ , CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=36391956 } A wild bird belonging to the Common Goldeneye Species. Source: WOAH,  https://wahis.woah.org/#/in-review/6956 ____

  Highlights     • This Situation report will now be published monthly.  • All clades of the monkeypox virus (MPXV) continue to circulate. When mpox outbreaks are not rapidly contained and human-to-human transmission is not interrupted, there is a risk of sustained community transmission.   • In September 2025, 42 countries , across all WHO regions, reported a total of 3135 confirmed cases , including 12 deaths (case fatality ratio [CFR] 0.4%). More than 80% of these cases were reported in the African Region . Four regions (African Region, Eastern Mediterranean Region, Region of the Americas, and the Western Pacific) observed a declining trend in confirmed cases reported per month, while the European and South-East Asian regions observed an increase in cases in September 2025. • Seventeen countries in Africa have experienced ongoing active transmission of mpox in the last six weeks (14 Sep – 19 Oct 2025), with 2862 confirmed cases, including 17 deaths (CFR ...

  Abstract Recently, highly pathogenic avian influenza (HPAI) A (H5N1) clade 2.3.4.4b viruses have caused mass mortality events in seabirds worldwide, raising concern for long-lived species with low reproductive rates. Using individual-level data from the 2022 mass mortality event in northwestern European Sandwich terns (Thalasseus sandvicensis), we show that older individuals were disproportionately more affected , while no sex bias was observed. This age-specific mortality likely removed the most experienced individuals from the population. Our findings highlight a previously underappreciated mechanism through which HPAI outbreaks may impair the resilience of long-lived avian populations . Competing Interest Statement The authors have declared no competing interest. Funder Information Declared German Federal Agency for Nature Conservation (BfN) Federal Ministry for the Environment, Climate Action, Nature Conservation and Nuclear Safety (BMUKN) Source: BioRxIV,  https://www.b...

  Abstract Background :  Monitoring antigenic drift in human influenza A viruses is essential for vaccine strain selection and ensuring protection against circulating strains. Antigenic drift is traditionally assessed using ferret antisera , which provide monospecific responses , and human vaccinee sera , which reflect exposure to multiple antigens. In this study we evaluated the pig as an alternative source of antisera to study antigenic drift compared to immune responses in ferrets and humans. We included seasonal influenza A(H1N1pdm09) human viruses that had shown different antigenic characteristics when using ferret or human antisera.  Methods :  Pairs of pigs were inoculated with six human A(H1N1)pdm09 viruses circulating between 2019 and 2023, a period of marked antigenic drift. Pig and ferret antisera were analysed by hemagglutination inhibition (HI) and virus neutralization (VN) assays.  Results :  Pigs were successfully infected with all strains, s...

  Key Points -- Question :  Have asymptomatic infections with highly pathogenic avian influenza A(H5N1) virus been reported in humans? -- Findings:  This scoping review of published reports through August 25, 2025, identified 10 reports of 18 cases of asymptomatic infection with A( H5N1 ) virus, including 2 cases with molecular and serologic confirmation and 16 cases with molecular confirmation alone. Symptom ascertainment methods varied among reported cases. -- Meaning:   Asymptomatic human avian influenza A(H5N1) virus infections have been infrequently reported , with most lacking serologic confirmation; prospective surveillance studies with serial respiratory and serum sampling and detailed symptom monitoring for persons with high-risk exposures could provide data to inform future public health responses. Abstract Importance    Since 1997, more than 1000 infections with highly pathogenic avian influenza A(H5N1) virus among humans have been reported globa...

  Abstract Background Changes in the vaccine advisory process in the United States have disrupted immunization guidance , which reinforces the need for independent evidence review to inform decisions regarding immunization for respiratory viruses during the 2025–2026 season. Methods We conducted a systematic review of U.S.-licensed immunizations against coronavirus disease 2019 (Covid-19), respiratory syncytial virus (RSV), and influenza . We searched databases on PubMed/MEDLINE, Embase, and Web of Science for updates of the most recent review by the Advisory Committee on Immunization Practices (ACIP) Evidence-to-Recommendations for each disease, which was performed during the 2023–2024 period. Outcomes included vaccine efficacy and effectiveness against hospitalization, other clinical end points, and safety. Results Of 17,263 identified references, 511 studies met the inclusion criteria. Covid-19 mRNA vaccines against the XBB.1.5 subvariant had pooled vaccine effectiveness against...

  Abstract Highly pathogenic avian influenza virus H5N1 has been infecting dairy herds in the U.S. since its initial incursion into cows in early 2024 . Although national strategies have aimed to detect affected herds , the best way to surveil herds for the H5N1 virus has not been formally studied and we also do not understand herd-level patterns of infection . To understand infection patterns of H5N1 in dairy herds over time, we conducted early surveillance of non-affected farms in California in the Fall of 2024 in an observational study. Daily bulk tank milk (BTM) samples were submitted from each herd and tested for influenza A (IAV) via rRt-PCR. In a subset of herds, IAV testing of multiple excretion types from cattle of different classes and pen-level daily milk was also completed soon after BTM detection. Daily detections of IAV occurred in BTM for a minimum of 33 days , with some herds continuing to have detection beyond a 75-day window. BTM Ct nadirs were seen between 1-3 we...

  {England, Suffolk} Turkey fattening unit.  Source: WOAH,  https://wahis.woah.org/#/in-review/6954 ____

  Abstract Since 2020, high pathogenicity avian influenza virus (HPAIV) infections in wild birds have been frequently reported . Because HPAIV infection has occasionally caused outbreaks in captive rare birds , application of antiviral drugs for treatment purposes against them has been considered from the perspective of conservation medicine . In this study, the therapeutic efficacy of baloxavir marboxil (BXM) was evaluated using a duck model to help establish the post-infection treatment for rare birds . Sixteen four-week-old ducks were divided into four groups and intranasally inoculated with the HPAIV strain A/crow/Hokkaido/0103B065/2022 ( H5N1 ). BXM was orally administered once daily at doses of 12.5, 2.5, 0.5, and 0 mg/kg to each of the four groups from 2 to 6 days post-infection. Blood samples were collected at 2, 8, and 24 hours after the initial BXM administration to measure the plasma concentrations of its active form, baloxavir acid (BXA). All ducks were monitored until ...

  Last updated 27 October 2025 Latest update UKHSA is aware of small numbers of locally-acquired cases of clade Ib mpox in the USA , Spain, Italy , the Netherlands and Portugal which have no connection to countries with known clade Ib mpox transmission.   This suggests there is now community transmission of clade Ib mpox globally . Most of the new cases identified in Europe and the USA have been in gay, bisexual and other men who have sex with men , a population in which clade Ib mpox transmission has not previously been observed.   Mpox is usually a mild infection , and clade Ia and Ib mpox are no longer classified as a high-consequence infectious disease (HCID). However, it can be severe in some cases.  The UK has a routine mpox vaccination programme in place for eligible groups, including those who:   -- have multiple sexual partners   -- have group sex   -- visit sex-on-premises venues   Studies show that the vacc...

A wild bird from Gruidae Spp. in Saarland Region. Source WOAH,  https://wahis.woah.org/#/in-review/6940 ____

  Abstract Avian influenza viruses (AIVs) are a global public health risk; human infection is typically associated with high mortality . While the relationship between several mammalian adaptive mutations and host factors have been described, it is unknown whether additional uncharacterised mutations lead to adaptation. Here, we combine phylogenetic analysis and complementary experimental methods to quantify the impact of novel mutations that emerge at the avian-mammal interface . We constructed phylogenetic trees of mammalian and avian influenza sequences for the polymerase (PA, PB1, PB2) and nucleoprotein (NP) segments and identified potential avian to mammal spillover events. We found >6500 mutations across the polymerase and NP, including known signatures of mammalian adaptation such as PB2 E627K and D701N which occurred independently in mammals 143 and 56 times respectively. We selected 95 mutations which were mostly undescribed and emerged independently multiple times in a...

  A protection zone (3km) and a surveillance zone (10 km) have been put in place around the infected farm and all other restrictions and necessary measures according to Regulation (EU) 2016/429 and (EU) 2020/687. {Tomelilla} Fattening turkeys. The turkeys were reported showing clinical signs of increased mortality 24 October and were euthanasia was finalized 26 October. A protection zone (3 km) and a surveillance zone (10 km) have been put in place around the infected farm and all other restrictions and necessary measures according to Regulation (EU) 2016/429 and EU DR 2020/687 are applied. Source: WOAH,  https://wahis.woah.org/#/in-review/6939 ____