ETIDIOH - NEW

ABSTRACT Influenza A (H3N2) viruses are historically responsible for the 1968 Hong Kong flu pandemic. Since then, H3N2 has continued to circulate as a seasonal influenza virus in humans. Public health concerns were raised in 2022 when human infections with novel reassortant H3N8 influenza viruses originating from chickens were first reported in China . Here, we conducted a systematic surveillance of H3 avian influenza viruses (AIVs) circulating in poultry and assessed the public health risk of emergent H3 reassortants. We found that H3 AIVs were prevalent in both ducks and chickens . Notably, in December 2022, a novel chicken-derived H3N3 subtype virus was identified, which gradually replaced the previously predominant H3N8 virus and became prevalent in chickens. Genetic analysis demonstrated that the novel H3N3 virus is a triple-reassortment strain with the H3 gene segment from chicken H3N8 virus, the N3 gene segment from the H10N3 virus , and internal gene segments derived from H9N2 ...

Summary Background Onradivir (ZSP1273) is a potent inhibitor of the PB2 subunit of influenza A virus (IAV) polymerase . Our previous, phase 2 clinical trial showed that a 600 mg regimen of onradivir initiated within 48 h of symptom onset can expedite the recovery of adult patients from acute, uncomplicated influenza. Here, we aimed to evaluate the safety and therapeutic efficacy of onradivir in a larger group with acute, uncomplicated influenza. Methods This randomised, double-blind, multicentre, placebo-controlled and oseltamivir-controlled, phase 3 trial was conducted at 68 clinical sites in China . Eligible participants were adults (aged 18–64 years) with an influenza-like illness who screened positive by rapid IAV antigen testing at the first clinical visit, and had a fever (axillary temperature ≥38·0°C) with at least one moderate systemic and one moderate respiratory symptom within 48 h of symptom onset. Patients were randomly assigned into three treatment groups, stratified by in...

Abstract Nationwide surveillance of avian influenza viruses (AIVs) in live poultry markets across China has occurred since 2014, providing a resource for AIV prevalence and genetic diversity studies . Here we report that 3,237 of 18,425 samples from poultry were AIV positive (17.57%) between 2019 and 2023, with H9N2 being the dominant subtype . We developed an automated phylogeny-based nomenclature system to classify genetic clades of the dominant H9N2 lineage, the BJ94 lineage. Using this model, we found that ten haemagglutinin (HA) sub-subclades cocirculated in poultry and showed antigenic variation. In addition, 99.46% and 96.17% of H9N2 AIVs in 2021–2023 possessed human-receptor binding-related HA-L226 and human MxA-resistance-related NP-N52 mutations , respectively. H9N2 strains with these two mutations preferred human-type receptors and increased replication in human cells in vitro, regardless of the presence of PB2-V/K/E627. Moreover, H9N2 AIVs containing HA-L226, PB2-V/K627 and...

  New human cases {2}:  -- From 23 April to 27 May 2025, based on reporting date, the detection of influenza A( H5N1 ) in three humans, the detection of influenza A( H9N2 ) virus in eight humans and the detection of influenza A( H10N3 ) in one human were reported officially.  -- Circulation of influenza viruses with zoonotic potential in animals:  - High pathogenicity avian influenza (HPAI) outbreaks in poultry and non-poultry animals 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 in these events. Based on information available at the time of the risk assessment , the overall public health risk from currently known influenza viruses circulating at the human-animal interface has not c...

Abstract Background Avian influenza, a significant threat to public health , requires monitoring for the development of control strategies. This study aims to analyze the spatiotemporal distribution of avian influenza virus in the external environment of Xinjiang from 2021 to 2023, to enhance understanding of its transmission patterns and provide a scientific basis for public health response measures. Methods A total of 3913 avian-related environmental samples were collected from nine monitoring areas in Xinjiang . Sample types included poultry drinking water, meat cutting boards, cage surfaces, feces, and wastewater. Real-time RT-PCR was used to detect nucleic acid for H5, H7, and H9 subtypes. Data were statistically analyzed using Excel and SPSS, and spatial distribution was visualized through Kriging interpolation using ArcGIS. Results Among the collected samples, 810 tested positive , with an overall positivity rate of 20.70%. The H9 subtype was predominant , accounting for 85.43% ...

Abstract Mpox clade Ib is significant as it is associated with human cases and plays a key role in understanding the transmission and public health implications of mpox outbreaks. Here we present a case report of the first confirmed human infection of clade Ib in China , which occurred in December 2025 in Zhejiang Province. The case was a 28-year-old woman from South Africa who had sexual contact with an asymptomatic man from the Democratic Republic of the Congo . She presented with disseminated vesicular lesions on the extremities, face, buttocks, trunk, palms, and dorsum of the hands, but lesions were absent from the oral cavity, perineum, and anus. By the 18th day post-onset (DPO), only vesicles remained on the dorsum of the right foot and in the finger web spaces, with complete resolution by the 24th DPO. Among 59 consecutive samples collected, 55 tested positive for mpox virus . Oropharyngeal swabs turned negative by the 16th DPO, while skin lesion samples, urine samples, and scab...

{Excerpts} Influenza A H5N1 Virus -- Date : 23/05/2025,  -- Location : China*, Guangxi Zhuang Autonomous Region,  -- Sex : Female,  -- Age : 53,   -- Clinical Status : Recovered,  -- Virus Subtype : H5N1. (...) Source: Centre for Health Protection, Hong Kong PRC SAR,  https://www.chp.gov.hk/files/pdf/2025_avian_influenza_report_vol21_wk21.pdf ____

Abstract The Eurasian avian-like swine (EA) H1N1 virus has been widely prevalent in the Chinese swine population and has caused infections in human . However, knowledge regarding its pathogenic mechanisms remains limited. In this study, we analyzed the pathogenic determinants of two G4 genotype EA H1N1 viruses (A/Swine/Guangdong/SS12/2017 and A/Swine/Jiangxi/1110/2017) with differing pathogenicity by constructing a series of reassortant and mutant viruses . The HA-G219A mutation was found to be determinant of pathogenicity in mice. Subsequent analyses revealed that this mutation enhances viral replication in human cells , improves thermal stability , reduces HA activation pH, and alters receptor-binding properties . Furthermore, HA-G219A mutation may be an adaptive mutation that facilitates influenza virus adaptation to swine , with its prevalence increasing in the swine population. This mutation may support cross-species transmission of EA H1N1 swine influenza viruses or genetic excha...

  {Excerpt} Avian influenza A(H9N2) :  -- New Cases (New Deaths): 8 (0)  - Chongqing Municipality :  - 1) A 67-year-old man with onset on April 18, 2025.  - Guizhou Province :  - 2)  A one-year-old girl with onset on April 7, 2025.  - 3) A one-year-old girl with onset on April 15, 2025.  - Hunan Province :  - 4) A five-year-old boy with onset on April 1, 2025. - 5) A seven-year-old girl with onset on April 1, 2025.  - 6) A one-year-old girl with onset on April 3, 2025.  - 7) A five-year-old boy with onset on April 19, 2025 - Yunnan Province : - 8) A one-year-old girl with onset on April 2, 2025 Avian influenza A(H10N3) :  - Guangxi Zhuang Autonomous Region :  - 1) A 68-year-old woman with onset on April 13, 2025.  (...) Source: Centre for Health Protection, Hong Kong PRC SAR,  https://www.chp.gov.hk/files/pdf/2025_avian_influenza_report_vol21_wk19.pdf ____

Abstract In February 2024, H5N1 highly pathogenic avian influenza viruses (HPAIVs) of clade 2.3.4.4b were first reported in dairy cows in the USA. Subsequent multiple outbreaks on dairy farms and sporadic human infections have raised substantial public health concerns . In the same year, four H5N1 HPAIVs of clade 2.3.4.4b were isolated from ducks and geese in live poultry markets (LPMs) spanning seven provinces in China . Evolutionary analysis demonstrated that these viruses had undergone two genetic reassortments with H5 influenza viruses from wild birds in different countries. Except for 565/H5N1, the other three viruses exhibited over 99% genetic homology with avian-origin H5N1 HPAIVs from South Korea and Japan . Notably, 571/H5N1 demonstrated high replication efficiency in bovine-derived cells , particularly in bovine mammary epithelial (MAC-T) cells, and caused 16.7% (1/6) mortality in mice at a dose of 10⁵ EID₅₀/50 μL, indicating its zoonotic potential . Given the potential cross...

Abstract Background The prevalence and transmission of avian influenza viruses (AIVs) in the live poultry market (LPM) is a serious public health concern . This study was to investigate the prevalence of different subtypes of avian influenza viruses in environment of LPM, and to analyze the differences and seasonality of the nucleic acid positive rate (NAPR) of A type, H5, H7, and H9 subtypes in feces, sewage, drinking water, breeding cages, and chopping boards . Methods Feces, breeding cages swabs, drinking water, sewage and chopping boards swabs were collected from live poultry market during 2019–2023 from southern and northern China . Real-time PCR was used to screen for virus subtypes. Viruses were isolated, and deep sequencing was performed to obtain whole-genome sequences. Chi-square test was used for statistical analysis of categorical variable, GraphPad Prism software were used to construct graphs. Results A total of 64,599 environmental samples were collected from live poultry...

Abstract Recently, Clade 2.3.4.4b H5N1 virus has been widely prevalent globally. Although no outbreaks of Avian Influenza have occurred in poultry in China recently, Clade 2.3.4.4b H5 virus can still be isolated from wild birds , live poultry markets and environment , indicating the ongoing co-circulation of H5N1 and H5N6 viruses. In this study, phylogenetic analysis of global Clade 2.3.4.4b viruses and 20 laboratory-isolated H5 strains revealed that Chinese H5N1 and H5N6 viruses since 2021 cluster into two distinct groups , G-I and G-II. Bayesian phylodynamic analysis reveals that G-I H5N6 virus has become an endemic virus in China . In contrast, G-II H5N1 virus, with South China as its main epicentre, has been disseminated in China and its surrounding countries, with its transmission more reliant on the connections of wild birds and waterfowl . Reassortment analysis indicates that since 2023, Clade 2.3.4.4b H5 viruses isolated in China have formed seven genotypes . The genome of H5 v...

{Excerpt} The Centre for Health Protection (CHP) of the Department of Health today (April 23) received a report of a case of severe paediatric COVID-19 and human metapneumovirus (hMPV) infection and reminded the public to observe personal, hand and environmental hygiene at all times. High-risk individuals should receive a COVID-19 vaccination as soon as possible and receive booster doses at appropriate times to minimise the risk of serious complications and death after infection. The case involves an eight-month-old girl with good past health, who developed a fever and runny nose since April 19 and sought medical attention from a private doctor the next day. She developed cough and shortness of breath on April 21 and sought medical attention from another private doctor. She attended the Accident and Emergency Department of Hong Kong Adventist Hospital – Tsuen Wan on April 22 and was transferred to the Paediatric Intensive Care Unit of Princess Margaret Hospital for treatment on the sam...

Abstract Gammacoronavirus (γ-CoV) primarily infects poultry, wild birds, and marine mammals . The widespread distribution and circulation of γ-CoV in the ecological environment may lead to sustained transmission and economic loss . To better understand the diversity of γ-CoV in wild birds , we collect 482 wild-bird fecal samples from Yunnan , encompassing fourteen bird species . We detected twelve γ-CoV positive samples in five bird species, with the characterization of five complete genomes - HNU5-1, HNU5-2, HNU5-3, HNU6-1, and HNU6-2 -indicating that these genomes represent two viral species . The HNU5 strains were derived from Black-headed gull (Chroicocephalus ridibundus), while the HNU6 strains were came from Mallard (Anas platyrhynchos), and both of those were recombinant. The HNU5 strain exhibited the highest sequence identity (95.45%) with a γ-CoV strain isolated from Numenius phaeopus (GenBank accession: PP845452). Similarly, the HNU6 strain showed 95.18% nucleotide identity w...

{Excerpt} Avian influenza A(H9N2) :  -- Guangxi Zhuang Autonomous Region :  - A five-year-old boy with onset on March 3, 2025.  -- Guizhou Province :  - A 35-year-old woman with onset on March 10, 2025.  -- Henan Province - A seven-year-old girl with onset on February 11, 2025.  (...) Source: Centre for Health Protection, Hong Kong PRC SAR,  https://www.chp.gov.hk/files/pdf/2025_avian_influenza_report_vol21_wk15.pdf ____

Abstract In November 2022, we reported a fatal case of human infection caused by a highly pathogenic avian influenza A(H5N6) virus bearing a clade 2.3.4.4b HA gene in Changsha City . We investigated the transmission route and distribution of the H5N6 virus in the largest live-poultry market (LPM), which is linked to the human infection. A total of 1357 samples from the LPM were collected for avian influenza A virus detection from 2020 to 2023. The proportion of LPM samples positive for H5 subtype avian influenza virus was 14.30% (194/1357). Sequences of H5N6 (n = 10) and H5N1 (n = 4) avian influenza viruses were obtained from the LPM samples using next-generation sequencing. The complete genome sequence of the H5N6 virus from the human infection case, A/Changsha/1/2022(EPI_ISL_16466440), was determined and analyzed. The PB1 and PB2 segments shared 99.65% and 99.23% sequence identity with A/duck/Hunan/S40199/2021(H5N6) and A/Whooper swan/Sanmenxia/H615/2020(H5N8), respectively. The othe...

Abstract Objective :  To analyze the epidemiological, etiological and genetic characteristics of influenza virus in Shandong Province during 2023-2024.  Methods :  The surveillance data of influenza-like illness (ILI) in sentinel hospitals in Shandong from 2023 to 2024 were collected and analyzed. The isolated influenza strains with hemagglutination titers ≥8 were selected for antigenicity analysis , drug susceptibility test, gene sequencing and evolutionary analysis .  Results :  From 2023 to 2024, the positive rate of influenza virus in Shandong was 8.51% (23 663/277 995), the highest positive rate was in the age group of 5-14 years (15.78%, 6 073/38 478), and the highest positive rate was in the 49th week (35.86%, 2 264/6 313). Both antigenicity analysis and evolutionary analysis showed that the A(H1N1)pdm09 subtype and B(Victoria) strain had good matching effect and close evolutionary distance with the 2023-2024 surveillance year vaccine strain. The A(H3N2) ...

Highlights •  Scientific question :  Cross-species transmission of influenza A viruses from swine to humans occurs occasionally because their tracheal epitheliums possess both sialic acid α-2,6-Gal and α-2,3-Gal receptors . In 2011, the first human case of swine influenza virus infection in the mainland of China was detected in Jiangsu Province . Subsequently, the Eurasian avian-like H1N1 swine influenza virus (EAH1N1 SIV) had sporadically crossed the host barrier and infected humans, raising public concern for its pandemic potential. •  Evidence before this study :  A/Jiangsu/1/2011 (H1N1v) was first discovered in 2011 and belongs to the G1 genotype. The G4 and G5 genotypes that appeared successively in 2013 are recombinant H1N1 swine influenza viruses. The EAH1N1 SIVs from 2016 to the present are dominated by the G4 genotype, with hemagglutination (HA) and neuraminidase (NA) genes derived from the EAH1N1 SIVs, non-structural protein (NS) genes derived from the trip...

Abstract Background In late 2023, the first human case caused by an H10N5 avian influenza virus (AIV) was diagnosed in China . H10Ny AIVs have been identified in various poultry and wild birds in Eurasia, the Americas, and Oceania. Methods We analyzed the clinical data of the H10N5 AIV-infected patient, isolated the virus, and evaluated the virus receptor-binding properties together with the H10N8 and H10N3 AIVs identified in humans and poultry. The genomic data of the human-infecting H10N5 strain and avian H10Ny AIVs (n = 48, including 16 strains of H10N3 and 2 strains of H10N8) from live poultry markets in China , during 2019–2021, were sequenced. We inferred the genetic origin and spread pattern of the H10N5 AIV using the phylodynamic methods. In addition, given all available nucleotide sequences, the spatial-temporal dynamics, host distribution, and the maximum-likelihood phylogenies of global H10 AIVs were reconstructed. Findings The first H10N5 AIV-infected human case co-infected...

Abstract Since 2022, three cases of human infections of novel H3N8 avian influenza viruses (AIVs) have been confirmed in China . Given the potential for significant public health implications , the prompt detection and containment of the virus is particularly important. Comprehensive analyses were conducted of the complete viral gene sequences of five H3 subtype AIVs that were isolated from chickens, pigeons, and geese in live poultry markets in China in 2023. Four strains exhibited a high degree of homology with the H3N8 viruses responsible for human infections in 2022 and 2023. A subsequent study was conducted to investigate the pathogenicity differences among multiple subtypes of the H3 AIVs in chickens. The study revealed that all infected chickens exhibited clinical signs and viral shedding. Notably, two H3N8 viruses, which were highly homologous to human strains, demonstrated significant differences in adaptability to chickens. The goose-derived H3N5 strain displayed high adaptab...