#Genomic #epidemiology of two #travel-associated #pediatric #measles viruses within the B3 Lineage

 

Highlights

    • The Children’s Hospital of Philadelphia (CHOP) detected a B3 MeV case in 2023 and in 2025.

    • Whole-genome amplification of the two CHOP B3 MeV isolates was performed.

    • The CHOP genomes were assessed with a global dataset of all 168 National Center for Biotechnology Information B3 MeV near-full length genomes from 2005-2025.

    • The CHOP isolates form a clade with 39 other isolates from four countries, 36 of which cluster with a 15 single nucleotide polymorphism cutoff.

    • The CHOP clade diverged in 2019, contains the most recently emerged B3 nodes, and shares a private mutation in the phosphoprotein at a codon undergoing positive selection.

Abstract

Background

Children’s Hospital of Philadelphia (CHOP) identified a MeV case in late 2023 and also early 2025, both of which were associated with international travel. Of the 24 MeV genotypes, the B3 and D8 lineages have been the most prevalent globally since 2021. Initial genotyping indicated that the two CHOP isolates belong to the B3 lineage.

Objectives

To inform MeV molecular surveillance, we conducted a genomic epidemiology analysis to situate the CHOP strains within the global genetic landscape of past and present MeV B3 cases.

Study design

We performed whole-genome amplification, genome assembly, and phylogenomics of our two MeV cases. These strains were then analyzed alongside all 168 National Center for Biotechnology Information near-full length MeV B3 genomes using population and evolutionary genetic approaches. This dataset includes strains isolated from 13 countries between 2005 and 2025.

Results

The two CHOP strains form a monophyletic group with 39 other isolates from four countries; 36 clade members form a discrete network connected by a 15 single nucleotide polymorphism (SNP) cutoff. The CHOP clade shares a Q45H phosphoprotein mutation at a codon undergoing diversifying selection, as with a H593R hemagglutinin mutation carried by the 2025 CHOP strain. The CHOP clade likely diverged in 2019 and has a median root-to-tip distance of 0.020 compared to 0.017 for the other B3 strains, consistent with this clade encompassing the most recently divergent nodes.

Conclusions

Our work places the CHOP MeV cases within a diversifying and emergent global clade of the dominating B3 lineage that is a future risk due to ongoing B3 MeV transmission.

Source: 

Link: https://www.sciencedirect.com/science/article/abs/pii/S1386653226000557?dgcid=rss_sd_all

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The #risk of #global #Ebola virus #spread is low: #epidemiology of Ebola disease cases outside Africa, 1976 to May 2026

 

Abstract

Following the Bundibugyo virus disease outbreak reported in the Democratic Republic of the Congo in May 2026, we reviewed all known Ebola disease cases outside Africa and found that intercontinental transmission risk remains low. We identified 28 confirmed epidemic-linked cases outside Africa; only four involved travellers with latent infection whose symptoms were detected after border screening. Excluding medically evacuated cases, the crude overall risk since 2000 was 0.17 Ebola disease cases outside Africa per 1,000 reported cases in Africa.

Source: 

Link: https://www.eurosurveillance.org/content/10.2807/1560-7917.ES.2026.31.24.2600508?emailalert=true#abstract_content

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#Overview of available modelling #evidence to inform the scale and potential spread of #Bundibugyo virus in the current #Ebola disease #outbreak (ECDC, June 17 '26, summary)

 

ASSESSMENT | 17 June 2026

Key findings 

    • So far in the current outbreak of Ebola disease caused by Bundibugyo virus, international modelling efforts have focused on estimating the outbreak size and near-term trajectories, as well as the risk of regional and international spread.  

    • Multiple modelling groups suggest that the true size of the outbreak is larger than reported. 

        - One model estimated that cumulative infections as of 13 June were between 3.0 and 10.2 times the reported number of cases (90% credible interval). 

    • Epistorm estimated the relative risk of importation to be highest for Rwanda, Tanzania and Kenya, which together account for approximately 54% of the relative risk. 

        - ECDC has estimated the risk of importation into the EU/EEA to be low. 

    • The United States Centers for Disease Control and Prevention published scenario modelling analysis results that estimated a 65% probability that the outbreak will exceed 20 000 cases within three months under a scenario where 20% of individuals with Bundibugyo virus infection were isolated and no other interventions were implemented. 

    • Current modelling estimates are highly uncertain due to data limitations. 

        - Multiple epidemic trajectories remain compatible with the available surveillance data, limiting confidence in estimates of outbreak size and future trends. 

(...)

Suggested citation: European Centre for Disease Prevention and Control. Overview of available modelling evidence to inform the scale and potential spread of Bundibugyo virus in the current Ebola disease outbreak. ECDC: Stockholm; 2026.   ISBN 978-92-9498-899-7; doi: 10.2900/3614787; Catalogue number TQ-01-26-044-EN-N 

© European Centre for Disease Prevention and Control, Stockholm, 2026

(...)

Source: 

Link: https://www.ecdc.europa.eu/en/publications-data/overview-available-modelling-evidence-inform-scale-and-potential-spread

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Seasonal #influenza versus #COVID19 #hospitalisation #risk during the 2025–26 influenza season

 

{Excerpt}

(...)

Contemporary surveillance data have shown higher population rates of influenza infections and hospitalisations during the 2025–26 influenza season; however, these aggregate metrics cannot disentangle infection frequency from disease severity. This analysis extends that evidence by comparing outcomes on a per-infection basis among patients with multiplex-based, laboratory-confirmed infection, showing that seasonal influenza was associated with a 43% higher risk of hospitalisation than COVID-19, corresponding to approximately 48 additional hospitalisations per 1000 infected individuals. The higher severity associated with seasonal influenza during this season likely reflects a combination of factors, including the increased virulence of circulating influenza strains, mismatch between vaccine composition and dominant circulating influenza variants, and the continued attenuation of SARS-CoV-2 severity over successive waves.

(...)

Source: 

Link: https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(26)00289-6/fulltext?rss=yes

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Regional #Signals Preceding the 2026 #Bundibugyo Virus Disease #Outbreak

 

Highlights

    • Bundibugyo virus circulated undetected for months prior to outbreak declaration.

    • Four earlier regional hemorrhagic fever clusters flagged by open surveillance are unresolved.

    • These clusters warrant urgent reanalysis due to concern for regional spread.

Abstract

Background

The May 2026 Bundibugyo virus disease (BVD) outbreak in the Democratic Republic of the Congo was declared a Public Health Emergency of International Concern after substantial undetected community transmission. We describe regional surveillance signals detected by the Biothreats Emergence, Analysis, and Communications Network (BEACON), our open access event based surveillance program, in the weeks preceding outbreak declaration.

Methods

We reviewed BEACON reports of VHF-compatible illness clusters detected in the transboundary DRC-Uganda-Burundi-South Sudan region during March–April 2026, prior to the May 15 laboratory confirmation of BDBV.

Results

BEACON detected four temporally proximal VHF-compatible illness signals: (1) March 9, North Kivu Province—suspected Ebola case under investigation with unresolved laboratory results; (2) March 10, Kasaï Province—fatal hemorrhagic illness with secondary cases and negative Ebola PCR; (3) March 30, Burundi—35-case undiagnosed cluster near the DRC border with 5 deaths, negative testing for major filoviruses and >200 pathogens, pending metagenomic sequencing; (4) April 22, South Sudan—three suspected VHF cases with negative initial testing. All four signals shared a similar diagnostic phenotype: VHF-compatible presentation, mobilization of investigation teams, negative initial testing, and no publicly reported confirmed etiology. None were formally reported to have been resolved.

Conclusions

Our detection of four unresolved VHF signals preceding the confirmed BDBV outbreak highlights gaps in formal follow-up mechanisms for negative cases and fragmented regional diagnostic coordination. In light of confirmed BDBV circulation and Africa CDC's identification of 10 countries at high risk for spread, these preceding signals warrant urgent retrospective investigation and laboratory.

Source: 

Link: https://www.ijidonline.com/article/S1201-9712(26)00497-2/fulltext

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#Scenario #analysis for potential #community spread of #Andes virus (ANDV)

 

Abstract

We simulated the potential community spread of Andes virus (ANDV) following the introduction of a single infectious individual in a generic population, based on epidemiological parameters derived from a human-to-human historical outbreak. Under current available evidence, our analyses suggest that, within 4 months from the index case’s symptom onset, the expected outbreak size is unlikely to exceed 50 cases, with a high probability of epidemic extinction, particularly when > 50% cases are effectively isolated from the start of the outbreak.

Source: 

Link: https://www.eurosurveillance.org/content/10.2807/1560-7917.ES.2026.31.22.2600425#abstract_content

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Breeding #pig #transport drives the dispersal of #swine #influenza A virus across #Europe

 

Abstract

Pigs serve as reservoirs of former human influenza A virus (IAV) H1N1 and H3N2 lineages and act as mixing vessels for diverse strains, facilitating the emergence of novel IAVs. Understanding the spread and evolution of swine IAVs (swIAVs) is therefore crucial to assess the risk of strains with zoonotic potential emerging. This study uses a phylogeographic framework to investigate the predictors of swIAV dispersal across Europe. All publicly available swIAV genomic sequences were retrieved and subsampled for the ten largest European pig-producing countries. Discrete phylogeographic reconstructions were conducted for H1, H3, N1, N2 encoding genes and all internal gene segments. Our analyses indicate that viral dispersal predominantly occurred from north-western to southern and eastern Europe, with frequent long-distance transitions between non-adjacent countries. We also extended the discrete phylogeographical analyses with generalized linear models to test the association between viral movement and potential predictors, such as live pig trade, pork trade, pig densities, farm sizes, or the geographic distance between key pig production zones. We find that breeding pig trade is the only consistently well-supported predictor of between-country transition events, whereas pork trade and geographic distance were not supported. This highlights that farms importing breeding pigs from multiple countries could act as hotspots for reassortment of diverse swIAV strains. Strengthening external biosecurity on farms with emphasis on quarantining breeding pigs, limiting long-distance transport, and implementing a One Health surveillance system for earlier detection of emerging strains, could help curb the rapid spread and evolution of swIAV in Europe.

Competing Interest Statement

The authors have declared no competing interest.

Source: 

Link: https://www.biorxiv.org/content/10.64898/2026.06.01.729471v1

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Increased burden of #influenza #H1N1pdm09 in older adults following the #COVID19 #pandemic

 

Abstract

Of the two influenza A virus (IAV) subtypes circulating endemically in humans, A/H3N2 and A/H1N1pdm09, A/H3N2 has historically been the dominant driver of disease burden in older adults. Based on an analysis of publicly available global surveillance data from 2015 to 2025 (>300,000 subtyped, age-stratified infections), we report a substantially increased contribution of A/H1N1pdm09 to influenza morbidity in older adults since approximately 2022. Birth cohort-stratified analyses suggest elevated A/H1N1pdm09 burden among individuals born before 1955-1959, consistent with erosion of pre-existing immunity originally generated by exposure to historical A/H1N1 strains. Pooled estimates across datasets and analytical approaches indicate the increase in A/H1N1pdm09 burden rises with earlier birth year, ranging from 1.22-fold (95% CI 1.08-1.37) for the 1955-1959 birth cohort to 3.10-fold (95% CI 2.58-3.72) for the 1930-1934 cohort. These findings point to a substantial rise in the overall influenza burden among the most vulnerable age groups, with implications for vaccine policy, clinical management, and public health planning.

Competing Interest Statement

C.A.R. has received consulting fees from CSL Seqirus, Moderna, Pfizer, GSK, and Sanofi for advisory services unrelated to this work.

Source: 

Link: https://www.medrxiv.org/content/10.64898/2026.05.20.26353664v1

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Two #epidemics, one #genotype, different outcomes: evolutionary #changes of Avian #Influenza #H5N1, genotype EA-2024-DI

 

Abstract

Since 2020, high pathogenicity avian influenza H5Nx viruses of clade 2.3.4.4b have become enzootic in Europe, causing recurrent epidemic waves characterized by extensive reassortment events. Here, we describe the emergence of a single high-fitness genotype (EA-2024-DI) that has driven two consecutive waves, evolving into distinct sub-lineages. While its circulation is ongoing, during the 2025-2026 wave it caused an unprecedented number of cases in wild birds. Using phylodynamic analyses of a large dataset of genomic sequences, we compared the spatial diffusion and host transmission pattern of the EA-2024-DI sub-lineages across the three most recent epidemic waves (2023-2024, 2024-2025 and 2025-2026). We show that the genotype has persisted over time and has spread primarily through wild Anseriformes, but with a marked change in the transmission patterns between the different waves and a shift in the epicenter from Eastern to Central Europe, the latter having emerged as an important hub for virus diffusion throughout Europe. Our results reveal a recent increase in the frequency of viruses from wild and domestic mammals carrying mutations enhancing virus replication in mammalian hosts, highlighting the importance of proactive monitoring of this group of hosts to better understand its role in the virus ecology and evolution.

Competing Interest Statement

The authors have declared no competing interest.

Funder Information Declared

Funded by the European Union under grant agreement (101084171) - (Kappa-Flu). Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or REA. Neither the European Union nor the granting authority can be held responsible for them

Support for this work was provided by the European Union within the framework of the activities foreseen by the European Union Reference Laboratory for Avian Influenza and Newcastle Disease under grant agreement 101201937

Source: 

Link: https://www.biorxiv.org/content/10.64898/2026.05.25.727580v1

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Spatiotemporal #Dynamics of Highly Pathogenic Avian #Influenza #H5 Virus Introductions and Regional Spread in the Republic of #Korea

 

Abstract

Highly pathogenic avian influenza (HPAI) viruses from clade 2.3.4.4 have caused recurrent outbreaks in poultry since 2014. In the Republic of Korea, clade 2.3.4.4b viruses have driven five epidemic waves, yet the factors underlying HPAI introduction and farm-to-farm spread remain poorly understood. We compiled hemagglutinin gene sequences of clade 2.3.4.4b viruses from wild birds and poultry in the Republic of Korea (October 2016–March 2024) and reconstructed dispersal dynamics using Bayesian phylogeography. Dispersal patterns suggest that domestic duck farms in the western provinces likely form a key interface for spillover from wild birds into poultry. Mixed-effects generalized linear models showed that both wild-to-poultry and farm-to-farm transition rates were positively associated with the number of poultry farms in the destination province, while wild-to-poultry rates were further associated with higher avian influenza virus infection probability among wild birds. Wild-to-poultry transition rates were lower in 2020–2024 than in 2016–2018, which may reflect strengthened interventions. These findings suggest that poultry farm abundance and introduction pressure from wild birds jointly shape the spatial dynamics of HPAI introduction and spread. More broadly, these factors may provide operational indicators to guide risk-based surveillance and control strategies.

Competing Interest Statement

The authors have declared no competing interest.

Source: 

Link: https://www.biorxiv.org/content/10.64898/2026.05.21.726857v1

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Computational Structural Analysis Predicts #Host-Range Promiscuity and #Antiviral #Resistance in North #American #H5N1 Lineages

 

Abstract

Influenza A virus has been circulating in birds in Eurasia for more than 146 years, but human infection has been sporadic. H5N1 (clade 2.3.4.4b) has recently infected hundreds of species of wild and domestic birds and mammals in North America. Infections include 71 people in the United States. There have been 2 human fatalities (United States and Mexico). We have integrated time-series analysis, molecular phylogenetics, and structural biology to understand how H5N1 is circulating in North America and adapting to new hosts. Our time-series analysis reveals that the circulation of H5N1 follows a distinct seasonal pattern, with cases in the United States increasing November to April. We also document an increase in the number of cases reported since 2021. We show that H5N1 spreads in North America as 2 distinct lineages. These viral lineages have achieved a vast host range by efficiently binding the viral surface protein hemagglutinin to both mammalian and avian cell surface receptors. This novel host-range promiscuity is concomitant with the strengthening of the viral polymerase basic 2 protein binding for mammalian and avian immune proteins. Once bound, the immune proteins have diminished ability to fight the virus, thus allowing for efficient replication. Our analyses predict that while most antivirals remain effective, a fatal human isolate showed reduced binding to multiple drugs from different classes. The H5N1 virus is causing an animal pandemic through promiscuity of host range and strengthening ability to evade the innate immune systems of both mammalian and avian cells.

Source: 

Link: https://spj.science.org/doi/10.34133/csbj.0066

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Epidemiological study of #hantavirus in Southern #Brazil, 2009-2019

 

ABSTRACT

Brazil has the highest number of hantavirus cardiopulmonary syndrome cases on the American continent, with Santa Catarina being the state with the most notifications. This retrospective longitudinal study aimed to describe the epidemiological profile of 177 hantavirus cases reported in Santa Catarina from 2009 to 2019, using data from the Notifiable Diseases Information System (SINAN). Statistical analyses of socio-demographic, clinical, and epidemiological data revealed that the typical patient was a male of working age with low educational attainment, living in a rural area. The highest incidence occurred in the Santa Catarina West, Midwest, and Mountain regions, strongly associated with agricultural activities. The case fatality rate (CFR) was highest among the 15-19-year age group. Clinical risk factors for death included respiratory signs, increased hematocrit, and the need for mechanical ventilation. Patients who sought early care had a higher CFR, possibly due to the initial difficulty of differentiating hantavirus from other viral diseases. Conversely, regions with higher notification rates showed lower CFRs, suggesting better surveillance. This study highlights critical areas for public health intervention and the key characteristics of hantavirus patients (males in rural areas and adolescents aged 15-19 years in regions with low notification rates) and areas for public health intervention. Training for medical professionals in regions with low notification rates should aim to reduce lethality, especially in regions with low reported cases (Itajai river delta and South), where underreporting may be occurring. Furthermore, the high lethality in adolescents and in patients with non-specific initial symptoms requires greater awareness. This study shows the utility of a governmental database in identifying epidemiological patterns and creating public health strategies tailored to regional specificities.

Source: 

Link: https://www.scielo.br/j/rimtsp/a/VB7LM8DjmVJ9yJBwYzSjzMh/?lang=en

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Disentangling the drivers and host-mediated #global #spread of #H7 #influenza A virus

 

Abstract

Avian influenza H7 viruses pose a significant zoonotic and pandemic threat, yet their evolutionary dynamics, spatial transmission patterns, and host-specific roles remain underexplored. This study integrates phylodynamic and phylogeographic analyses to map global H7 dissemination, quantify host-specific contributions, and identify key ecological and anthropogenic drivers. Epidemiological data show key epidemic waves in Asia during 2013-2014 and 2016-2017, and in Africa in 2023. The Eurasian and American lineages of H7 viruses exhibit transmission with a median velocity of ~661 km/year and ~354 km/year, though spread varies significantly by virus subtype. Anseriformes (~587 km/year) and wild birds (~654 km/year) spread the Eurasian lineage of H7 viruses more rapidly and over greater distances than Galliformes and domestic birds. Geographic distance is negatively associated with the spread of the H7 virus, while temperature and poultry density show positive association. In this work, we identify Asia as an important H7 virus evolutionary epicenter. Anseriformes drives transcontinental spread, whereas Galliformes facilitates local amplification. The dynamics of the H7 virus are shaped by ecological and socioeconomic factors. A One Health approach emphasizing targeted surveillance and global cooperation is essential to mitigate cross-species transmission and future pandemic threats.

Source: 

Link: https://www.nature.com/articles/s41467-026-72718-9

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#Human #infections with avian #influenza #H5 viruses with potential #pandemic #risk: 1997–2025

 

ABSTRACT

Highly pathogenic avian influenza (HPAI) A(H5) viruses have caused sporadic human infections since 1997, with recent detections in the Americas and Asia. However, the evolutionary dynamics of different HPAI A(H5) viruses at the animal–human interface, along with their associated disease severity, propensity for animal-to-human (zoonotic) spillover, and human-to-human transmission potential, remain unclear. Here, we combine available genetic and epidemiological data with mechanistic models to better understand the global spread of HPAI A(H5) viruses that spilled over to humans in 1997–2025. Analysis of 7445 subsampled hemagglutinin gene sequences revealed frequent regional succession of HPAI A(H5) virus clades that varied by geographic location. The 1104 reported human HPAI A(H5) cases exhibited subtype- and clade-specific heterogeneity in age, gender, and exposure sources (p < 0.001). After adjusting for under-reporting, we estimated case-fatality risk to be low for HPAI A(H5N1) clade 2.3.4.4b (0.7%, 95%CI: 0.02%–3.9%) and for A(H5N6) clades 2.3.4x (0%, 0%–1.1%) and 2.3.4.4b (1.6%, 0.7%–3.2%), compared with other A(H5) clades (range: 4.7%–15.0%). We also show that, while the transmissibility of HPAI A(H5) viruses between humans remains very low to date (mean Rt: 0.10–0.23), zoonotic transmission has increased with the emergence of bovine-origin clade 2.3.4.4b (incidence: 7.85 per million people per year), relative to other avian-origin A(H5) clades (range: 1.54–5.04 per million people per year). Although other factors such as exposure sources, routes of transmission, immune function, underlying medical conditions, and clinical management can influence outcomes of case-patients, these findings highlight the ongoing pandemic threat posed by HPAI A(H5) viruses and the need for ongoing comprehensive surveillance, genotypic and phenotypic characterization, and preparedness.

Source: 

Link: https://academic.oup.com/nsr/article/13/7/nwaf471/8317928

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Mechanistic #modelling of highly pathogenic avian #influenza: A scoping #review revealing critical gaps in cross-species #transmission models

 

Abstract

Background

Highly pathogenic avian influenza (HPAI) viruses, particularly subtypes such as H5N1 and H7N9, have caused widespread outbreaks in wild birds, poultry, livestock and occasionally humans, raising concerns about cross-species transmission and pandemic potential. Effective control and surveillance strategies require a thorough understanding of HPAI transmission dynamics, which can be supported by mathematical modelling.

Objective

This scoping review aimed to identify mechanistic models used to study HPAI transmission. Specifically, we sought to categorize model types, describe their application contexts (e.g., wild birds, poultry, livestock, and humans), and highlight modelling gaps relevant to understanding and mitigating the risks of HPAI spread.

Methods

Following PRISMA guidelines and the PRISMA extension for scoping reviews (PRISMA-ScR), we conducted systematic searches of PubMed and Web of Science to identify peer-reviewed studies employing deterministic and stochastic models to analyze HPAI transmission. Eligible articles published between January 2023 and June 2025 were screened and grouped by model structure, host populations, transmission pathways, and modelling objectives.

Results

After screening, 30 studies published after 2023 were included in this scoping review. Compartmental models were the most common (26 studies), with 16 deterministic and 10 stochastic approaches. These models were primarily used to describe transmission among wild birds, poultry, livestock, and humans and to evaluate interventions such as culling, vaccination, and movement restrictions. Agent-based models (2 studies) captured individual-level interactions and spatial heterogeneity, while network models (2 studies) represented contact structures and transmission pathways between farms or species.

Conclusions

Currently, mechanistic modelling of HPAI is dominated by compartmental approaches, including both deterministic and stochastic formulations, whereas agent-based and network models remain relatively underused. Although most studies focus on transmission in wild birds and poultry, and in some cases spillover infections to humans, few explicitly examine infection dynamics in livestock or in transmission between livestock and humans, despite the importance of livestock (e.g., cattle) as potential intermediaries in human infection. Key gaps persist in the integration of empirical data, representation of multi-host interactions, and evaluation of realistic intervention strategies. Addressing these limitations is essential to improve predictive accuracy and to strengthen the role of modelling in informing HPAI surveillance and control.

Source: 

Link: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0347929

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Seasonal forcing and waning #immunity drive the sub-annual periodicity of the #COVID19 #epidemic

 

Abstract

Seasonal trends in infectious diseases are shaped by climatic and social factors, with many respiratory viruses peaking in winter. However, the seasonality of COVID-19 remains in dispute, with significant waves of cases across the United States occurring in both winter and summer. Using wavelet analysis of COVID-19 cases during the pandemic period, we find that the periodicity of epidemic COVID-19 varies markedly across the U.S. and correlates with winter temperatures, indicating seasonal forcing. However, seasonal forcing alone cannot explain the pattern of multiple waves per year that has been so characteristic of COVID-19. Using a modified SIRS model that allows specification of the tempo of waning immunity, we show that specific forms of non-durable immunity can sufficiently explain the sub-annual waves characteristic of the COVID-19 epidemic.

Source: 

Link: https://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1014169

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Using an evolutionary epidemiological #model of #pandemics to estimate the #infection #fatality ratio for #humans infected with avian #influenza viruses

 

Abstract

The risk of highly pathogenic avian influenza virus infection to humans is challenging to estimate as many human avian influenza virus (AIV) infections are undetected because infections may be asymptomatic, symptomatic but not tested, and difficult to identify through contact tracing, as human-to-human transmission is rare. We derive equations that consider the evolutionary mechanisms that give rise to pandemics and are parameterized to be consistent with records of past pandemics. We estimate that thousands of human AIV infections occur worldwide in an average year and estimate the infection fatality ratio as 32 deaths per 10,000 infections (95% confidence interval: [9.6, 75]). This estimate is comparable to SARS-CoV-2 during the recent pandemic and higher than seasonal human influenza. We estimate that preventing animal-to-human influenza spillovers would delay pandemic emergence by several years. Preventing human infections with AIV is necessary given the high risk of severe outcomes to individuals and to reduce the risk of pandemics occurring in the future.

Competing Interest Statement

The authors have declared no competing interest.

Funding Statement

AH was supported by a Natural Sciences and Engineering Research Council of Canada Discovery Grant (RGPIN 023-05905) and a Catalyst Grant: Avian Influenza OneHealth Research, Enhanced tracking of the circulation of and risk from highly pathogenic avian influenza viruses at the human-wildlife interface from the Canadian Institutes of Health Research. JM, ML, and AH were support by an Atlantic Canada Research in the Mathematical Sciences Collaborative Research Group award.

Source: 

Link: https://www.medrxiv.org/content/10.64898/2026.01.21.26344526v2

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Deep #disadvantage in #mortality on the frontlines of the #COVID19 #pandemic

 

Abstract

This study presents new evidence on the temporal and spatial impact of the COVID-19 pandemic on mortality among especially vulnerable New Yorkers. Using burial records from Hart Island—the City’s potter’s field—we study the distribution of unclaimed deaths over time and across boroughs in 2020 compared to pre-pandemic levels. We show that the Hart Island deaths began deviating from their historical pattern in early March 2020 and peaked five weeks later at 22 deaths for every death in the same week in 2019 (20:1 adjusted). COVID-19 excess death rates were more than twice as high in the Bronx compared to other boroughs. Citywide, we estimate that 10% of all COVID-related excess deaths during the initial outbreak (March–August 2020) were unclaimed. These findings suggest the pandemic greatly magnified existing inequalities in the City and, more broadly, illustrate the especially devastating impact of COVID-19 on economically and socially vulnerable populations.

Source: 

Link: https://www.nature.com/articles/s41598-026-41219-6

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#Genomic analysis of high pathogenicity avian #influenza viruses from #Antarctica reveals multiple introductions from South #America

 

Abstract

The spread of high pathogenic avian influenza virus (HPAIV) H5N1 clade 2.3.4.4b into Antarctica poses a major threat to polar wildlife. We report the detection of H5N1 in carcasses of eight species during the 2023-2024 and 2024-2025 austral summers in the South Shetland Islands: Antarctic shag, Antarctic tern, kelp gull, pintado petrel, Antarctic petrel, skuas, Antarctic fur seal, and southern elephant seal. Whole-genome sequencing, mutational profiling, and phylogenetic reconstruction revealed that the viruses detected in these hosts descended from distinct introduction events. One group of strains including complete and partial viral genomes from a gull, skuas, fur seals, an Antarctic tern, and a southern elephant seal clustered with H5N1 strains previously detected in marine mammals in South America and formed a polyphyletic lineage consistent with at least two independent introductions into Antarctica. A second group of strains including complete and partial viral genomes from petrels, shags, and skuas clustered with H5N1 strains previously detected in seabirds and marine mammals in South Georgia and with a previously reported HPAIV detection from Torgersen Island, Antarctic Peninsula. These findings reveal extensive epidemiological connectivity between South America and Antarctica, with South Georgia serving as a “stepping stone” for virus spread in the region.

Source: 

Link: https://www.nature.com/articles/s41467-026-71544-3

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#Oropouche virus #outbreaks in northeast #Brazil between 2024–25 are characterized by sustained #transmission and spread to newly affected areas

 

Abstract

Oropouche virus (OROV) has recently expanded in Brazil, establishing transmission in non-endemic regions. This study aims to integrate epidemiological and molecular data to investigate OROV spread in Northeast (NE) Brazil between 2024 and 2025. OROV cases were analyzed regarding ecological risk factors and geographical clustering. Additionally, we sequenced 65 new OROV genomes from the Northeast states of Pernambuco, Paraíba, and Sergipe to infer the virus’s spatiotemporal dynamics in NE Brazil. A total of 2,806 confirmed cases were reported between March 2024 and April 2025, affecting 170 municipalities across eight out of nine NE states, with highly heterogeneous incidence. An ecological shift was observed, with OROV transmission moving from Atlantic Forest areas in 2024 to humid Caatinga zones in 2025. Phylogenetic reconstruction revealed multiple independent viral introductions in Northeast in 2024, including two in Pernambuco. The first, originating from the central Amazonas, became the main driver of local transmission and subsequently spread to Sergipe and Paraíba, causing outbreaks in 2024 and 2025, respectively. The second introduction remained restricted within Pernambuco. While several Northeast municipalities reported high OROV incidence, Jaqueira (Pernambuco) emerged as a key hub for regional viral spread. OROV showed sustained transmission in the region over a two-year period, characterized by marked spatiotemporal displacement consistent with short-lived, rapidly spreading outbreaks, followed by cryptic transmission and subsequent dissemination to new areas, ultimately driving renewed intense outbreaks.

Source: 

Link: https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0014171

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