Journal of Travel Medicine
◐ Oxford University Press (OUP)
Preprints posted in the last 90 days, ranked by how well they match Journal of Travel Medicine's content profile, based on 18 papers previously published here. The average preprint has a 0.01% match score for this journal, so anything above that is already an above-average fit.
Hagag, N. M.; Adel, A.; Zaher, M. R.; Zanaty, A.; Said, D.; Shaaban, A.; Saleh, M. M.; Nabil, N. M.; Tawakol, M. M.; Hassan, H. M.; Hussien, W. I.; Radwan, N.; Tennakoon, C.; Al-Aqnas, H.; Eid, S.; Mosaad, Z.; Ibrahim, A. S.
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High pathogenicity avian influenza (HPAI) H5 clade 2.3.4.4b is the main driver of the ongoing unprecedented global panzootic. The recently emerged HPAI H5N1 clade 2.3.4.4b genotype EA-2024-DI.2.1 has become predominant in Europe, with migratory wild birds, particularly waterfowl, playing a major role in its dissemination. Egypt lies along major Afro-Eurasian migratory flyways, which have historically played an important role in the introduction of emerging H5Nx viruses into the country. In this study, targeted surveillance was conducted on 416 wild birds offered for sale in in live bird markets (LBMs) and roadside trading points in northern Egypt, mainly in Damietta and Port Said. Of these, 118 birds showing mild clinical signs were examined post-mortem and lung and tracheal tissues were collected, while oropharyngeal and cloacal swabs were collected from apparently healthy birds. Avian influenza virus was detected by RT-qPCR in 22 wild birds, all from tissue samples, whereas all swabs from apparently healthy birds were negative. Waterfowl accounted for 16 of the 22 positive birds (72.7%), with Eurasian teal showing the lowest Ct values (21-25). Phylogenetic and whole-genome analyses showed that the sequenced wild-bird viruses clustered within the recently emerged EA-2024-DI.2.1 sub-lineage and were closely related to contemporary European viruses. Compared with the EA-2021-AB genotype currently circulating in Egyptian poultry, the EA-2024-DI.2.1 viruses showed several HA amino acid differences, including A83D, L104M and T195A. These findings provide evidence for the introduction of EA-2024-DI.2.1 into Egypt through migratory wild birds and highlight the importance of continued genomic surveillance at the wild bird domestic poultry interface and antigenic evaluation against vaccines currently used in Egypt.
Fanelli, F.; Parino, F.; Pelle, M. A.; Wang, B.; Boum, Y.; Fallah, M.; Mbala, P.; Luvande Okingo, R.; Ronin, V.; Yazdanpanah, Y.; Poletto, C.; Valdano, E.; Colizza, V.
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The ongoing 2026 Bundibugyo Ebola outbreak in the Democratic Republic of the Congo and Uganda raises concerns about regional dissemination across Africa. Anticipating where imported infections are most likely to occur, and whether recipient countries are prepared to detect and contain them, is essential for prioritizing surveillance and response. We developed an integrated spatial framework combining high-resolution epidemic and population data, air and land mobility, geographical accessibility, conflict-adjusted travel times to estimate the risk of Ebola importation across African countries. We contextualized importation risk using different national readiness indicators. We quantified overall, air-mediated, and land-mediated importation risk under the current epidemic situation and evaluated outbreak amplification scenarios in major regional hubs. Importation risk was highly concentrated geographically, with neighbouring countries accounting for 85% of the estimated continental risk. However, high-risk destinations extended beyond the immediate neighbours, whereas some neighbouring countries remained at low risk, reflecting the complementary roles of land and air mobility in shaping regional dissemination. South Sudan, Rwanda, Kenya, Tanzania, Zambia, Ethiopia, Burundi, Angola, South Africa, the Central African Republic, and Nigeria were estimated at high risk, but differed markedly in healthcare system capacity and emergency preparedness and response. Readiness gaps were largest in South Sudan, Burundi, and the Central African Republic. Botswana, Burkina Faso, Cameroon, Chad, and Ghana emerged as a second tier of preparedness priorities, combining intermediate-high importation risk with low readiness. Under outbreak amplification scenarios, the highest-risk countries remained largely stable, but additional countries entered the high-risk group and continental importation pressure increased substantially, highlighting the need for dynamic preparedness planning. Integrating high-resolution epidemiological data with complementary land and air mobility provides a refined geography of regional risk and preparedness across Africa, supporting better targeted surveillance, preparedness investments, and international support while allowing priorities to be rapidly updated as outbreaks evolve.
Heitmann, A.; Höller, P.; Lange, U.; Mack, A.; Becker, N.; Schmidt-Chanasit, J.; Lühken, R.; Jansen, S.
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Barmah Forest Virus (BFV), an arthropod-born virus transmitted by mosquitoes, is of significant public health concern in Australia and regions in the Pacific. Recent climate change and globalization raise the potential for BFV to extend its geographic distribution. Despite the rising importance of BFV, its vector dynamics remain poorly understood, particularly concerning the vector competence of different mosquito species. This study aims to investigate the vector competence of BFV across various mosquito species, beyond those endemic to the Australasian region, especially focusing on global relevant vector species. No transmission was observed for Culex quinquefasciatus and Cx. torrentium as well as Anopheles stephensi. In contrast, both investigated Aedes species, Ae. aegypti as well as Ae. albopictus, exhibited BFV-positive saliva across all four temperature profiles (18{degrees}C, 21{degrees}C, 24{degrees}C or 27{degrees}C) examined. These two invasive mosquito species must therefore be classified as potential vectors for BFV, indicating the potential risk of BFV transmission outside of Australia.
Neave, M. J.; Hair, S.; Mileto, P.; Mahar, J. E.; Stevens, V.; Davies, K.; O'Dea, M.; Iqbal, S.; Ong, J. W. L.; Hughes, A.; Wang, J.; Fox, N.; Crowder, J. C.; Gillies, D.; Butler, J.; Grimsey, J.; McMahon, A.; Gagliardi, M.; Grech, E.; Ford, M.; Soul, C.; Poon, M.; Reid, T.; Colling, A.; McInnes, J. C.; Burgess, T. L.; Hodgson, J. C.; Boulinier, T.; Williams, D. T.; Luczo, J. M.; Bhardwaj, V.; O'Brien, D.; Eagles, D.; Baele, G.; Wong, F. Y. K.
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High pathogenicity avian influenza H5N1 clade 2.3.4.4b has caused a panzootic of devastating impact to poultry and wildlife globally. The Australian continent and broader Oceania until recently remained the last major region without confirmed detections. Here we report the first H5N1 clade 2.3.4.4b detections from two live seabirds - a brown skua and a southern giant petrel - found on the south coast of Western Australia in June 2026. Virus genome sequencing showed that both viruses were most closely related to H5N1 viruses detected recently on sub-Antarctic islands in the Southern Indian Ocean. In time-calibrated phylogeographic analyses, both viruses sampled in Western Australia clustered with viruses from Heard Island, a sub-Antarctic external territory of Australia. Ancestral location reconstruction also identified Heard Island as the most probable source location, although unsampled intermediate locations cannot be excluded. The two Western Australian detections were estimated to be independent incursions from Heard Island, rather than local transmission on mainland Australia. There was no evidence of reassortment with endemic avian influenza viruses in Australia, and both virus sequences retained key avian-like genetic markers and lacked known substitutions for reduced antiviral susceptibility. These detections revealed a Southern Ocean pathway of recurrent H5N1 incursions into Australia, highlighting the risk of potential establishment on the mainland and the need for heightened surveillance and rapid, nationally-coordinated, virus genomic characterisation.
Freitas, G. I.; Rodrigues, C. E.; Carvalho, D. E. V. d.; Utsunomia, R.; Porto-Foresti, F.
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International wildlife trade represents one of the major drivers of biodiversity exploitation worldwide. However, the true taxonomic diversity embedded within commercial wildlife products often remains unknown because processing removes diagnostic morphological characteristics, preventing reliable species identification. Consequently, biodiversity assessments based solely on product labels may substantially underestimate the diversity of species involved in trade networks. To investigate hidden biodiversity within wildlife trade products, we applied DNA barcoding based on the mitochondrial cytochrome c oxidase subunit I (COI) gene to 77 products commercialized as fish swim bladders and seized at Guarulhos International Airport, Brazil. Molecular analyses successfully identified all samples and revealed the presence of four species: Plagioscion auratus (n = 38), Cynoscion acoupa (n = 7), Melanosuchus niger (n = 17), and Caiman crocodilus (n = 15). Fish species accounted for 71.4% of all samples, whereas crocodilians represented 28.6%, demonstrating that products marketed under a single commercial category may conceal substantial taxonomic diversity. Notably, the occurrence of two Amazonian crocodilian species within a trade chain traditionally associated with fish products reveals a previously undocumented component of the international wildlife trade. Our findings demonstrate that DNA barcoding is an effective tool for uncovering hidden biodiversity within processed wildlife products and provide evidence that wildlife trade networks may involve a broader spectrum of species than suggested by commercial labels. These results highlight the importance of molecular surveillance for biodiversity monitoring, wildlife trade regulation, and conservation planning.
Harrison, L. E.; Duncan, D. H.; Flegg, J. A.; Price, D. J.; Kurucz, N.; Tolosa, X.; Neville, P. J.; Jansen, C. C.; Potter, A.; Brockway, C.; Miller, K. L.; Hobby, M.; Burns, V.; Glasgow, K. M.; Draper, A. D.; Schmidt, J.; Weerasinghe, G.; van den Hurk, A. F.; Williams, D. T.; Doggett, S. L.; Golding, N.; Shearer, F. M.
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Japanese encephalitis virus (JEV) is a leading cause of viral encephalitis in humans in Asia. Prior to 2021, only sporadic outbreaks had been detected in Australia's tropical northern extremes. However, during 2021-23, JEV infection was identified in 45 people and in more than 85 piggeries, together with many detections in feral pigs, mosquitoes, and other livestock across Australia, including in the temperate far south. Here we estimated the spatial extent of virus transmission during the outbreak (the realised niche) and the area environmentally suitable for transmission (the potential niche). We collated a national dataset of JEV surveillance and detection in humans, mosquitoes, domestic pigs, feral pigs, and sentinel chickens from 2021-23. We combined these data with (1) previously published predictions of habitat suitability for vertebrate host and vector species, and (2) estimated densities of humans, domestic pigs, and feral pigs, in a multipart assessment of spatial risk. Our model projected broad potential environmental suitability over much of northern and eastern Australia during the outbreak period, but floodplain wetland areas in the north and the inland east of Australia had both the highest estimated environmental suitability for transmission, and the strongest evidence for virus circulation.
Li, Y.-T.; Lin, Y.-T.; Chen, B.-S.; Kuo, C.-Y.; Huang, H.-Y.; Ko, H.-Y.; Huang, P.-Y.; Smith, G. J.; Lin, Y.-L.; Liu, M.-T.
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Low pathogenic avian influenza A(H7N7) virus detected in a poultry worker in Taiwan, 2026 was related to viruses circulating in Asian wild birds and possessed PB2 E627K, a mammalian adaptation marker. Enhanced surveillance for H7 viruses in poultry and rapid characterization of human cases are essential to assess pandemic potential.
Fay, R. L.; Banker, E. M.; Payne, A. F.; Dupuis, A. P.; Stout, J.; Russell, A.; Schnurr, V.; Bialosuknia, S. M.; Munn, L.; Mordecai, E. A.; Ciota, A. T.
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Japanese encephalitis virus (JEV) is an emerging mosquito-borne flavivirus with potential for geographic expansion, yet the risk of establishment in North America remains poorly characterized. We assessed vector competence of three North American Culex species (Cx. pipiens, Cx. quinquefasciatus, and Cx. tarsalis) for the JEV Nakayama strain, isolated from human brain in 1934 in Japan, across five constant temperatures (15, 20, 25, 30, and 33{degrees}C) at 4, 7, and 14 days post-feeding, quantifying infection, dissemination, and transmission rates. Vector competence was low but non-zero across all species. Cx. pipiens showed higher infection rates than the other species, whereas Cx. quinquefasciatus and Cx. tarsalis were minimally susceptible under these experimental conditions. Temperature had limited effects on infection and no detectable effects on dissemination or transmission. These findings suggest limited transmission potential of JEV Nakayama in North America, with Cx. pipiens as a relatively permissive vector.
Truong Thi Thanh, L.; Huynh, A.; Huynh, K.; Le, K. D.; Pham, T.; Tran, A.; Pham Thi Kim, T.; Thanh Nguyen, T.; Le Hong, N.; Nguyen Hong, T.; Ong, T.; Thai Thanh, T.
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Introduction Measles remains a major public health threat worldwide. Following a resurgence of cases, Ho Chi Minh City (HCMC) experienced a severe outbreak in 2024-2025 that differed from the 2018-2020 epidemic. We compared the epidemiology and transmission dynamics of these two outbreaks to inform future surveillance and vaccination strategies. Methods Line-list data for measles cases reported in HCMC between 2018 and 2025 were extracted from the infectious disease surveillance system. Demographic changes were assessed using cross-sectional age distributions and longitudinal birth-cohort analyses. Transmission dynamics were characterized by estimating the effective reproduction number (Rt) using the Cori and Wallinga-Teunis methods. Age-stratified Who-Infected-Whom transmission matrices were constructed to quantify within- and between-age-group transmission before and after interventions. Results The 2018-2020 outbreak primarily affected children under five years of age (median age 3.75 years, IQR 0.9-9.1), whereas the 2024-2025 outbreak shifted toward older age groups (median age 8.4 years, IQR 1-14). Birth-cohort analyses identified two major immunity gaps: children born during the COVID-19 immunization disruption (2019-2023) and adolescents and young adults born before 2014 who were not eligible for the 2018 outbreak response immunization campaign. The 2024-2025 outbreak also showed broader spatial spread and a reversed geographic trajectory compared with the earlier epidemic. Transmission patterns changed substantially, with the 2018-2020 outbreak sustained mainly by transmission among young children, whereas the 2024-2025 outbreak was driven by older age groups, with individuals >15 years acting as an important source of infection for infants. Conclusion The epidemiology of measles in HCMC has shifted from predominantly pediatric transmission to increasing involvement of adolescents and adults, reflecting accumulated immunity gaps across multiple birth cohorts. These findings suggest that age-restricted outbreak response immunization may leave residual susceptible populations that contribute to future outbreaks. Achieving sustainable measles elimination will require vaccination strategies that address historical immunity gaps across all vulnerable age groups, in addition to maintaining high routine childhood vaccination coverage.
Elsayed, A. M.; Barre, R. S.; Rahmani, A.; Escobedo, R. A.; Jeevan, T.; Nath, H.; Castro, E. M.; Shivanna, V.; Nogales, A.; Kobie, J.; Webby, R. J.; Abdelwhab, E. M.; Garcia-Sastre, A.; Martinez-Sobrido, L.
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The continued emergence of genetically diverse high pathogenicity avian influenza (HPAI) H5N1 viruses with zoonotic potential highlights the urgent need for developing vaccines capable of providing broad protection against multiple circulating clades. Here, we developed a one-shot, multivalent, live-attenuated influenza vaccine (LAIV) based on the temperature-sensitive (ts), cold-adapted (ca), and attenuated (att) influenza A/Ann Arbor/6/1960 master donor virus (MDV) that incorporates the hemagglutinin (HA) and neuraminidase (NA) glycoproteins from representative clades 2.3.4.4b (A/Louisiana/12/2024), 2.3.2.1a (A/Victoria/149/2024), and 2.3.2.1e (A/Cambodia/2302009/2023) H5N1 viruses. A single intranasal (IN) immunization of C57BL/6 mice with the multivalent LAIV elicited robust humoral immune responses, with immune sera exhibiting broad cross-reactivity against antigens from all three H5N1 clades included in the vaccine. Following homologous viral challenge, vaccinated C57BL/6 mice were completely protected from disease, demonstrating the immunogenicity and protective efficacy of the multivalent LAIV. By simultaneously targeting antigenically distinct H5N1 lineages with pandemic potential, this strategy expands antigenic coverage within a single LAIV to confirm pan-H5N1 protection. Together, these findings support the development and implementation of this multivalent LAIV as a broadly protective pan-H5N1 LAIV for pandemic preparedness. SignificanceThe increasing genetic diversity of zoonotic H5N1 viruses complicates vaccine design. We developed a multivalent live-attenuated influenza vaccine (LAIV) based on the temperature-sensitive, cold-adapted, and attenuated (ts, ca, att) master donor virus (MDV) influenza A/Ann Arbor/6/1960 backbone that expresses the hemagglutinin (HA) and neuraminidase (NA) glycoproteins of H5N1 clades 2.3.4.4b, 2.3.2.1a, and 2.3.2.1e. A single intranasal (IN) immunization with the multivalent LAIV induced broadly cross-reactive neutralizing antibody (NAb) responses and protected experimental vaccinated animals against homologous lethal viral challenge, demonstrating the feasibility of the multivalent LAIV to protect against H5N1 clades of highest concern to humans. These findings demonstrate the feasibility of developing and implementing this multivalent LAIV as a broad protective pan-H5N1 LAIV against divergent H5N1 viruses for human use.
Fosse, J. H. H.; Fuglei, E.; Bonfante, F.; Olsen, L.; Bordes, L.; Davidson, R. K.; Mork, T.; Myhrvold, I. K.; Engerdahl, L. T.; Venema, S.; Sturod, K.; Akerstedt, J.; Hungnes, O.; Ballmann, M. Z.; Begeman, L.; Nymo, I. H.; Tonnessen, R.; Ytrehus, B.
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The continued circulation of H5 clade 2.3.4.4b highly pathogenic avian influenza virus (HPAIV) has caused extensive mortality in wild bird populations worldwide with increasing spillover to mammals. In 2022, H5 HPAIV emerged in Svalbard, Norway, with subsequent detections in wild birds, walruses, polar bears, and arctic foxes. To understand the population-level exposure among Svalbard arctic foxes, we analysed body fluids from carcasses trapped in 2006-2015 (n = 56), 2023-2024 (n = 112), and 2024-2025 (n = 94) for antibodies to H5 avian influenza (anti-H5), influenza A nucleoprotein (anti-NP), and neuraminidase subtypes using ELISAs, haemagglutination inhibition (HI), and a multiplex assay. Only three samples from 2006-2015 tested positive for anti-H5 and were interpreted as false positives. In 2023-2024, seropositivity for anti-H5 was high (95%), supported by a lower anti-NP seropositivity (85%) and antibody profiles consistent with mixed H5N1 (42%) and H5N5 (52%) exposure. In 2024-2025, anti-H5 and anti-NP seroprevalences remained high (83% and 57%), with H5N5 (87%) exposure predominating over H5N1 (3%). A subset of anti-H5-positive samples tested positive by HI (2023-2024: 30%; 2024-2025: 14%). Juveniles with exposure limited to the previous season had higher odds of anti-H5 seropositivity in 2023-2024 than in 2024-2025 (OR 5.5). Analysis of paired lung extracts from a subset of individuals (n = 63) yielded results concordant with body fluids, using an indirect anti-H5 ELISA adapted for carnivores. Our findings demonstrate widespread H5 virus exposure. Together with occasional reports of progression to fatal HPAI, this highlights the need for continued population monitoring to evaluate ecological consequences.
Yan, V.; Park, S.-C.; Wiest, M. J.; Laghlali, G.; d'Acunzo, J. N.; Chung, C.; Levican, J.; El-Ayache, F.; Wong, P. T.; Schotsaert, M.
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Influenza virus infects the respiratory mucosa, highlighting the importance of mucosal immunity for early protection and transmission control. Here, we evaluated whether intranasal (IN) vaccination with recombinant trimeric hemagglutinin protein from A/Michigan/45/2015 (triHA) formulated with a combined mucosal adjuvant, nanoemulsion plus IVT, an RNA-based RIG-I agonist (NE/IVT), could protect guinea pigs against heterologous A/Netherlands/602/2009 challenge and reduce viral transmission. To compare mucosal and parenteral immunization, IN triHA/NE/IVT was benchmarked against IN triHA alone, IM triHA/AddaVax (IM triHA/Advx), and standard IM quadrivalent inactivated influenza vaccine (QIV). We also tested whether IN triHA/NE/IVT could boost IM QIV- primed immunity and included animals previously infected with A/Michigan/45/2015 to model pre-existing infection- induced immunity. Transmission was assessed by co-housing naive sentinels with vaccinated, challenged donors. IN triHA/NE/IVT induced systemic humoral responses comparable to IM triHA/Advx while generating superior nasal mucosal IgA responses. Unexpectedly, IM triHA/AddaVax also induced detectable, albeit lower, mucosal IgG and IgA, contrasting with prior mouse data and highlighting species-specific differences. IN triHA/NE/IVT boosting after IM QIV enhanced serum IgG and mucosal IgA compared with QIV prime-boost alone and increased cross-neutralizing activity against antigenically distinct A/Victoria/4897/2022. Both IN triHA/NE/IVT and IN Michigan/15 prior- infection prevented detectable viral shedding after challenge, and naive sentinels co-housed with IN triHA/NE/IVT- vaccinated donors remained seronegative. Together, these findings support NE/IVT as a potential mucosal platform capable of inducing robust systemic and mucosal immunity and boosting IM vaccine-primed responses.
Connor, C. H.; Wick, R. R.; Taouk, M. L.; Barden, J.; Dougall, S.; McAllister, J.; Judd, L. M.; Mercoulia, K.; Howden, B. P.; Ingle, D. J.
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Enteric fever is endemic to many low- and middle-income countries (LMICs), particularly those in sub-Saharan Africa, South and South-East Asia. The causative agents are typhoidal serovars of Salmonella enterica, including Typhi (S. Typhi) and Paratyphi A (SPA). There are no vaccines currently licensed for SPA, leaving antimicrobials as the only therapeutic option. Multi-drug resistance (MDR) S. Typhi is increasingly prevalent, but to date has not been detected in SPA. In Australia, cases of SPA are notifiable. Here we report on the genomic epidemiology of 208 cases of SPA in returned travellers to Australia, and their close contacts, from 2018 to 2025. A total of 15 unique genotypes were detected, and these were correlated with geographical regions of reported travel. There was a low incidence of antimicrobial resistance with only a single isolate carrying acquired resistance genes. Mutations in quinolone resistance determining regions were common across the genotypes, detected in 95.7% of isolates. A single isolate in a traveller returning from India was resistant to several first line antibiotics including: ampicillin, amoxicillin plus clavulanic acid, ceftriaxone, azithromycin and ciprofloxacin. The isolate carried a plasmid encoding an extended spectrum beta-lactamase (blaCTX-M-231), two macrolide resistance genes (mphA and ermB) and a quinolone resistance gene (qnrS1). Elements of the pangenome were explored, with stable maintenance of small plasmids encoding hypothetical proteins detected in four genotypes. Copy number variation in genes encoding surface antigen biosynthesis genes were detected in six genotypes. These biosynthesis genes are targets for one of the two SPA vaccines in development, and the potential variation in surface antigens could have implications for vaccine efficacy. Linking epidemiological data with genomic studies of SPA provides an opportunity to improve understanding of the emergence, spread and risk of drug-resistant SPA infections, and to better inform empirical treatment guidelines in returned travellers.
Stadler, E.; Csolle, M.; Mitchell, A.; Egilmezer, E.; Elias, K. M.; Bailey, B. A.; Cromer, D.; Turner, T.; Khoury, D. S.; Davenport, M. P.
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There are currently no approved vaccines or medical countermeasures for use in prevention or treatment of Bundibugyo virus disease. A critical question is whether the existing vaccines approved for use against Ebola virus disease could provide sufficient cross-reactivity and cross-protection against Bundibugyo virus disease. We performed a systematic review and meta-analysis of published studies of antibody cross-reactivity to Bundibugyo virus (BDBV) after vaccination with previously approved Ebola vaccines (Ervebo or Zabdeno/Mvabea). We find on average a 2.8-fold (95% predictive interval, PI: 2.6-3.0) drop in binding (n = 8 observations from 4 studies) and 3.1-fold drop (95% PI: 2.0-4.8) in neutralization (n = 2 observations from 1 study) between Ebola virus and BDBV antigens after Ervebo vaccination, which appears maintained over time after vaccination. Very limited data on cross reactivity after Zabdeno/Mvabea vaccination suggests a higher drop in recognition of BDBV (39.7-fold, 95% PI: 24.8-63.8; n = 3 observations from 2 studies). In addition to analysis of antibody recognition in humans, we also investigated evidence for vaccine protection from BDBV challenge in animal models after Ervebo or other recombinant vesicular stomatitis virus (rVSV) based vaccines containing only Ebola antigen. A single study in NHP showed non-significant vaccine protection from BDBV challenge, while a study in ferrets showed significant protection after both one and two doses. The available data demonstrate immune cross-reactivity and some evidence for protection in animals, although further clinical and pre-clinical data is urgently needed to inform decisions on the use of Ervebo to protect against Bundibugyo virus disease.
Elias, K. M.; Egilmezer, E.; Khan, S. R.; Mitchell, A.; Reynaldi, A.; Berry, M. T.; Schlub, T. E.; Bailey, B. A.; Cromer, D.; Turner, T.; Stadler, E.; Davenport, M. P.; Khoury, D. S.
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There is currently no clinical data for the effectiveness of the only licensed Ebola virus disease vaccine (Ervebo) against Bundibugyo virus disease. A number of studies have shown immune cross-reactivity with Bundibugyo virus after Ervebo vaccination. However, antibody recognition of Bundibugyo is around 2.8-fold lower than recognition of Ebola virus. Here, we aimed to infer how a 2.8-fold drop in immune recognition may affect Ervebo protection against Bundibugyo virus disease based on analysis of data on Ervebo immunogenicity and protection from Ebola virus disease. This work has three main components. Firstly, we analysed the timing of vaccine protection in the Ervebo pivotal ring vaccination clinical trial. Secondly, we performed a systematic review and meta-analysis of antibody responses to Ebola virus after Ervebo vaccination over time. Thirdly, we combined these data with previously reported data on the cross-reactivity to Bundibugyo virus to infer protection of Ervebo against Bundibugyo virus disease. We find that the clinical trial data for Ervebo supports vaccine protection beginning earlier than 10 days after vaccination. Secondly, binding antibody levels against Ebola virus on day 28 post vaccination (peak responses) were on average 12.9-fold (95% confidence interval, CI: 6.4 - 26.0) higher than on day 7, 6.3-fold (95% CI: 3.7 -10.8) higher than on day 10, and 2.5-fold (95% CI: 1.4 - 4.4) higher than on day 14 (neutralising antibodies showed similar results). Finally, we consider the scenarios where antibody levels to Ebola virus at day 7 or 10 are putative protective thresholds against Ebola virus disease, and we assume these thresholds also apply for Bundibugyo virus disease. Then, with a 2.8-fold reduction of responses to Bundibugyo compared to Ebola virus, we predict antibody responses to Bundibugyo virus after Ervebo vaccination are likely above these putative protective thresholds.
Reiten, M. R.; Boe, C. A.; Olsen, L.; Saghafian, M.; Rohringer, A.; Akerstedt, J.; Ytrehus, B.; Gjerset, B.; Granstad, S.; Hungnes, O.; Tonnessen, R.
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Since 2020, highly pathogenic avian influenza (HPAI) A(H5Nx) clade 2.3.4.4b viruses have spread globally, causing extensive outbreaks in domestic and wild birds. Increased circulation has resulted in frequent spillover to mammals, and occasional mammal-to-mammal transmission. Although human infections remain rare, the zoonotic potential of these viruses continues to be a public health concern. We investigated six cases of HPAI in red foxes (Vulpes vulpes) in Norway during 2022-2024 and identified infections with H5N1 and H5N5 viruses. Pathological and virological investigations demonstrated systemic infection, with prominent lesions in the brain and/or lungs. Phylogenetic analyses showed high similarity between viruses detected in foxes and those concurrently circulating in wild birds. The mammalian adaptation marker PB2:E627K was identified in one H5N1 virus and as a minority variant in a second H5N1 virus.
Jin, W.; Mitchell, A.; Stadler, E.; Foster, C. S. P.; Schlub, T. E.; Davenport, M. P.; Cromer, D. P.
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The continued evolution of SARS-CoV-2 has led to regular updates of the COVID-19 vaccine immunogen. However, the exact benefits of these updates for vaccine effectiveness in a real world context are difficult to evaluate. We performed a comprehensive meta-analysis of booster vaccine effectiveness in studies identified through the ViewHub systematic review. We integrated evidence from 44 studies reporting on effectiveness of mRNA booster vaccines containing XBB.1.5, JN.1 and KP.2 immunogens to assess the combined impact of booster immunogen, time since vaccination and calendar time at which a study was conducted. We estimate that the relative risk of severe disease increases by 9% [95%CI 7.4-10.5] each month following booster administration, likely due to antibody waning, and by an additional 2.4% [95%CI 1.2-3.6] for each calendar month, likely due to antigenic drift. Our findings show that COVID-19 booster vaccine effectiveness declines both with time after vaccination as well as calendar time since the vaccine immunogen emerged. This reinforces the need for regularly and timely vaccine immunogen updates.
Wight, J.; Liu, G.; Chan, M.; Medina, S. J.; Lu, D.; Cao, W.; Krosta, S. J.; Tierney, K.; Azaransky, K.; Banadyga, L.
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An uncontrolled and rapidly growing outbreak of Bundibugyo virus (BDBV) is currently gripping the Democratic Republic of the Congo and threatening health security across Central Africa. There are no available BDBV-specific vaccines, although emerging evidence suggests that the Ebola virus-specific vaccine, rVSV-EBOV (also known by its tradename ERVEBO), may offer cross-protective immunity. To directly address this question, we evaluated the efficacy of rVSV-EBOV in the uniformly lethal ferret model of BDBV infection. All vaccinated animals survived BDBV challenge and exhibited minimal clinical signs of infection, presumably as a result of a moderate--but protective--humoral immune response. These findings provide critical evidence further supporting the cross-protective efficacy of rVSV-EBOV, and they suggest a potential role for this vaccine in mitigating the ongoing BDBV outbreak.
Lim, L.; Lang, B.; Fenton, H.; Rose, K. C.; Hall, J.; Holmes, E. C.
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Traditional veterinary pathology investigations on wild animals generally conclude a primary cause of death based on a combination of observed clinical signs, gross and microscopic lesions, microbial culture and PCR. However, these methods may fail to capture the broader microbial community of the host. We employed metatranscriptomic sequencing to characterise the potential pathobiome of necropsied marine turtles, comparing these findings with corresponding veterinary pathology reports. Tissue samples were collected from 76 individuals spanning three species of marine turtles -- the green turtle (Chelonia mydas), the hawksbill turtle (Eretmochelys imbricata), and the loggerhead turtle (Caretta caretta) -- across the coastline of New South Wales, Australia. Reported causes of mortality ranged from infectious disease to trauma. We identified a diverse range of parasites within the genera Neospirochis, Hapalotrema, Paraorgymatobothrium, Eimeria and Callitetrarhynchus, and bacteria including the genera Aeromonas, Clostridium, and Vibrio. Novel viruses of the families Astroviridae, Caliciviridae, Hepaciviridae, Hepeviridae, Nyamivirdae, Orthomyxoviridae, Picobirnaviridae and Rhabdoviridae were also identified. In cases where infectious disease was noted in the pathology report, we frequently observed high pathogen read counts consistent with the listed primary diagnoses. However, we also detected a range of incidental infections involving eukaryotic parasites, bacteria, and viruses. The diversity of infectious agents detected in marine turtles suggests that the observed disease outcomes are unlikely to be driven by a single causative agent, but rather by complex interactions between host health, the pathobiome, and environmental stressors. We discuss the potential implications for turtle health and conservation.
Marjenberg, Z.; Peluso, M. J.; Wynberg, E.; Abduljawad, S.
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Objectives To evaluate the impact of COVID-19 vaccination on the prevention of long COVID (LC) in the Omicron era through an updated systematic review and meta-analysis. Methods We performed an update of our previously published systematic review and meta-analysis of vaccination and LC risk (searches between 1 January 2022 and 1 March 2024). Databases (Embase, MEDLINE, PubMed, Europe PMC, LILACS, Cochrane COVID-19 Study Register) were searched for studies published between 1 March 2024 and 13 July 2026. Observational studies assessing the impact of vaccination on the risk of LC four or more weeks after SARS-CoV-2 infection were included. Vaccines were restricted to those centrally authorised in the European Union. Random-effects meta-analyses, restricted to adults, were performed to calculate pooled odds ratios (OR) of LC in three comparisons: vaccinated (any dose) versus unvaccinated; booster vaccination versus unvaccinated; and booster vaccination versus primary course vaccination only. Results Nineteen new studies were identified, of which ten were included in the updated meta-analyses alongside eight studies from the original review. The pooled OR of LC in vaccinated adults (any dose) versus unvaccinated was 0.75 (95% confidence interval [CI] 0.67-0.84; 13 studies). ORs were also lower for booster vaccination versus unvaccinated (0.73; 95% CI 0.65-0.82; 6 studies), and booster vaccination versus primary course vaccination (0.63; 95% CI 0.53-0.75; 6 studies). Significant associations between vaccination and lower LC odds were observed in subgroup analyses of mRNA-only vaccination and LC outcomes three or more months after infection. Conclusions This updated review and meta-analysis reinforces our previous finding that vaccination may reduce the burden of LC in the Omicron era, with booster doses potentially providing additional protection. Although evidence in high-risk groups now prioritised for vaccination in most countries remains limited, these findings clearly demonstrate the benefits of vaccination and support current seasonal vaccination strategies.