ETIDIOH - NEW

February 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 1 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 docume...

Context and significance Wang et al. provided valuable insights into the epidemiological patterns of avian influenza virus (AIV) spillover and the role of H9N2 in the process. Their analysis highlighted the significant contribution of the internal genes (INGEs) from 12 key strains of H9N2 in facilitating human adaptability by reducing the species barrier between poultry and humans , essentially acting as internal genetic donors for AIV spillover . Due to its low pathogenicity, H9N2 has been neglected in poultry vaccination programs , leading to a lack of vaccines specifically targeting the INGEs of these 12 key strains. Their findings suggest that reducing the prevalence of H9N2 is fundamental to mitigating AIV spillover risks. Highlights •  H9N2 exerts a promoting effect on the spillover of avian influenza viruses (AIVs) •  Expansion of AIV spatial and host ranges reveals an emerging risk of its spillover •  Prevalence of AIVs in human -contacted hosts reveals a re-emerg...

ABSTRACT The H5N1 avian panzootic has resulted in cross-species transmission to birds and mammals, causing outbreaks in wildlife, poultry, and US dairy cattle with a range of host-dependent pathogenic outcomes . Although no human-to-human transmission has been observed, the rising number of zoonotic human cases creates opportunities for adaptive mutation or reassortment . This Gem explores the history, evolution, virology, and epidemiology of clade 2.3.4.4b H5N1 relative to its pandemic potential. Pandemic risk reduction measures are urgently required. Source: Journal of Virology,  https://journals.asm.org/doi/full/10.1128/jvi.02209-24?af=R ____

Abstract In the past two decades, two pandemic respiratory viruses (H1N1 and SARS-CoV-2) have emerged via spillover from animal reservoirs . In an effort to avert future pandemics, surveillance studies aimed at identifying zoonotic viruses at high risk of spilling over into humans act to monitor the `viral chatter' at the animal-human interface . These studies are hampered, however, by the diversity of zoonotic viruses and the limited tools available to assess pandemic risk. Methods currently in use include the characterization of candidate viruses using in vitro laboratory assays and experimental transmission studies in animal models . However, transmission experiments yield relatively low-resolution outputs that are not immediately translatable to projections of viral dynamics at the level of a host population. To address this gap, we present an analytical framework to extend the use of measurements from experimental transmission studies to generate more quantitative risk assessm...

Abstract A sustained outbreak of H5N1 influenza virus among wild fowl and domestic livestock has caused more than 70 zoonotic infections in humans in the United States , including one death. The Centers for Disease Control and Prevention has recommended rapid H5 subtyping for all hospitalized cases with influenza A virus infection to enable prompt initiation of antiviral treatment , as well as infection prevention and implementation of public health measures to control spread. To address these needs, we developed a multiplex RT-qPCR assay to subtype H5 influenza virus in nasal, nasopharyngeal, and conjunctival specimens with a limit of detection of 230 copies/mL. No cross-reactivity was observed with other common respiratory viruses, including seasonal H3N2 and H1N1 influenza A viruses. We retrospectively subtyped 590 influenza A-positive clinical specimens processed by University of Washington labs between March 2024 and February 2025, including 512 specimens collected during the 2024...

Abstract Introduction   In the light of the COVID-19 pandemic many countries are trying to widen their pandemic planning from its traditional focus on influenza. However, it is impossible to draw up detailed plans for every pathogen with epidemic potential. We set out to try to simplify this process by reviewing the epidemiology of a range of pathogens with pandemic potential and seeing whether they fall into groups with shared epidemiological traits.  Methods   We reviewed the epidemiological characteristics of 19 different pathogens with pandemic potential (those on the WHO priority list of pathogens, different strains of influenza and Mpox). We extracted data on the proportion of presymptomatic transmission , incubation period , serial interval and basic reproduction number (R0) for the targeted pathogens. We applied unsupervised machine learning (specifically K-means and hierarchical clustering) to categorise these pathogens based on these characteristics.  Resul...

Abstract Introduction :  Advanced outbreak analytics played a key role in governmental decision-making as the COVID-19 pandemic challenged health systems globally. This study assessed the evolution of European modelling practices , data usage, gaps, and interactions between modellers and decision-makers to inform future investments in epidemic-intelligence globally.  Methods :  We conducted a two-stage semi-quantitative survey among modellers in a large European epidemic-intelligence consortium. Responses were analysed descriptively across early, mid-, and late-pandemic phases. Policy citations in Overton were used to assess the policy impact of modelling.  Findings :  Our sample included 66 modelling contributions from 11 institutions in four European countries. COVID-19 modeling initially prioritised understanding epidemic dynamics. Evaluating non-pharmaceutical interventions and vaccination impacts became equally important in later phases. 'Traditional' surve...

{Summary} Pandemic influenza remains a significant global health threat, as signalled by the circulation and cross-species transmission of avian influenza A(H5N1) viruses from the clade 2.3.4.4b, including among dairy cattle in the USA since 2024. Although most of the reported human infections from the USA so far1,2 have been mild, the virus can change its profile rapidly. To reduce mortality and morbidity from influenza in humans, vaccines remain the most important intervention. (...) Source: Lancet Respiratory Medicine,  https://www.thelancet.com/journals/lanres/article/PIIS2213-2600(25)00052-9/fulltext?rss=yes ____

Abstract Background The direct and indirect impacts of the COVID-19 pandemic on life expectancy (LE) and years of life lost with and without disability remain unclear. Accounting for pre-pandemic trends in morbidity and mortality, we assessed these impacts in 18 European countries, for the years 2020–2022. Methods and Findings We used multi-state Markov modeling based on several data sources to track transitions of the population aged 35 or older between eight health states from disease-free, combinations of cardiovascular disease, cognitive impairment, dementia, and disability, through to death . We quantified separately numbers and rates of deaths attributable to COVID-19 from those related to mortality from other causes during 2020–2022, and estimated the proportion of loss of life expectancy and years of life with and without disability that could have been avoided if the pandemic had not occurred. Estimates were disaggregated by COVID-19 versus non-COVID causes of deaths, calendar...

As of February 28, 2025 CDC assessed the risk from H5N1 viruses to the U.S. general population and to populations in the United States with contact with potentially infected animals, including through contaminated surfaces or fluids . Risk describes the potential public health implications and significance of an outbreak for populations assessed. See definitions below for more detail. {Risk posed by H5N1 viruses to the United States. Please see methods section for further information on definitions of terms.} ___ The purpose of this assessment is to evaluate the current public health risk of H5N1 viruses to the general U.S. population and to those in contact with potentially infected animals or contaminated surfaces or fluids, and to inform public health preparedness efforts. CDC assessed risk by considering both likelihood and impact of infection in each population (...). Both the likelihood and impact of infection are assessed at a population level. Likelihood of infection refers to ...

{Summary} In outbreak situations involving a novel pathogen timely and coordinated response is crucial. The WHO Scientific Advisory Group for the Origins of Novel Pathogens recently released a global framework to guide future scientific investigations into the origin of emerging pathogens. Source: Nature Communications,  https://www.nature.com/articles/s41467-025-57218-6 ____

Abstract In late 2021, Eurasian-lineage highly pathogenic avian influenza (HPAI) A(H5N1) viruses from HA clade 2.3.4.4b were first detected in the United States . These viruses have caused severe morbidity and mortality in poultry and have been detected in numerous wild and domestic animals , including cows and humans . Notably, infected cows transmitted the virus to cats , causing extreme pathogenicity and death. While human-to-human spread of the virus has not been recorded, efficient transmission of the bovine-origin virus has also led to extreme pathogenicity and death in ferret models . Recently, markers in PB2 (E627K) and HA (E186D, Q222H), indicating mammalian adaptation mutations , were detected in an H5N1-infected patient manifesting critical illness in Canada . These, combined with instances of interspecies spread of the virus , have raised global public health concerns. This could highlight the potential for the virus to successfully adapt to mammals, posing a serious risk o...

{Summary} 1 Introduction The COVID-19 pandemic underscored the urgency of ensuring that the world is prepared for the next major respiratory pathogen pandemic (1). Corresponding with World Health Assembly resolutions WHA58 .5 (2) and WHA74.7 (3), WHO is committed to supporting Member States with pandemic preparedness planning through the provision of guidance and technical assistance . Following on from the PRET Global Meeting in April 2023, WHO has finalized guidance on Preparedness and resilience for emerging threats (PRET) module (1): planning for respiratory pathogen pandemics. This module acknowledges that similar systems and capacities can be used to prevent, prepare for and respond to different respiratory pathogens. The module (4) has three overarching objectives: - to guide countries and partners in developing or updating their integrated approach to respiratory pathogen pandemic preparedness for equitable and robust response; - to focus attention on the actions needed to stre...

Abstract Background The International Health Regulations (2005) (IHR), requires that States Parties develop their capacities to detect, assess, and respond to public health threats and report to the World Health Assembly through the States Parties Annual Report (SPAR). The National Pandemic Preparedness and Response Plans (PPRP) contribute to countries capacities however there are some discrepancies between both tools. To identify gaps and define priority actions to strengthen pandemic plans, we assessed the concordance between national pandemic preparedness and response plans for respiratory pathogens against the pandemic checklist published in 2023 and the SPAR. Methods In this retrospective, semi-quantitative study , conducted in August 2024, we reviewed the most recent respiratory pandemic plans for 35 PAHO member states and assessed their concordance with (1) actionable guidelines in the World Health Organization pandemic checklist and (2) IHR (2005) core capacities using the late...

Abstract Infectious disease outbreaks with pandemic potential present challenges for mitigation and control . Policymakers make decisions to reduce disease-associated morbidity and mortality while also minimizing socioeconomic costs of control. Despite ongoing efforts and widespread recognition of the challenge, there remains a paucity of decision tool frameworks that integrate epidemic and macroeconomic dynamics . Here, we propose and analyze an econo-epidemic model to identify robust planning policies to limit epidemic impacts while maintaining economic activity. The model couples epidemic dynamics, behavioral change , economic activity, and feasible policy plans informed by respiratory disease threats of pandemic concern . We compare alternative fixed, dynamic open-loop optimal control, and feedback control policies via a welfare loss framework. We find that open loop policies that adjust employment dynamically while maintaining a flat epidemic curve in advance of the uncertain arri...

Abstract Background Our study aims to enhance future pandemic preparedness by integrating lessons from historical pandemics, focusing on the multidimensional analysis of past outbreaks. It addresses the gap in existing modelling studies by combining various pandemic parameters in a comprehensive setting. Using Zurich as a case study, we seek a deeper understanding of pandemic dynamics to inform future scenarios. Data and methods We use newly digitized weekly aggregated epidemic/pandemic time series (incidence, hospitalisations, mortality and sickness absences from work) to retrospectively model the 1918–1920 pandemic in Zurich and investigate how different parameters correspond, how transmissibility changed during the different waves, and how public health interventions were associated with changes in these pandemic parameters. Results In general, the various time series show a good temporal correspondence , but differences in their expression can also be observed. The first wave in th...

 {Excerpt} (...) Now to the global spread of H5 avian influenza . Last year, 66 cases of H5 were reported from the United States , plus 10 from Cambodia, 2 from Viet Nam and one each from Australia, Canada and China. This is the highest number of reported human cases since 2015. So far this year, 2 cases including 1 death have been reported in the United States, and 1 death in Cambodia. Almost all these cases are associated with infected dairy cattle or poultry . H5N1 is of particular concern because since the first human cases were reported in 2003, it has killed almost half of those it has struck. Fortunately, H5N1 has not yet developed the ability to transmit easily between humans. But that could be only a matter of time. Every transmission from one animal to another , or to a human, is an opportunity for the virus to mutate, or to mix with other influenza viruses. It’s therefore imperative that the virus is not allowed to spread unchecked in animals. WHO is working closely with...