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

  September 2025   The development of influenza candidate vaccine viruses (CVVs), coordinated by WHO, remains an essential component of the overall global strategy for influenza pandemic preparedness . Selection and development of CVVs are the first steps towards timely vaccine production and do not imply a recommendation for initiating manufacture . National authorities may consider the use of one or more of these CVVs for pilot lot vaccine production , clinical trials and other pandemic preparedness purposes based on their assessment of public health risk and need.  Zoonotic influenza viruses continue to be identified and evolve both antigenically and genetically, leading to the need for additional CVVs for pandemic preparedness purposes.  Changes in the antigenic and genetic characteristics of these viruses relative to existing CVVs and their potential risks to public health justify the need to develop new CVVs. This document summarizes the antigenic and genetic c...

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

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

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

  ABSTRACT Common cold coronaviruses, such as OC43 and HKU1, typically cause mild respiratory infections in healthy people. However, they can lead to severe illness in high-risk groups , including immunocompromised individuals and older adults. Currently, there is no clinically approved vaccine to prevent infection by common cold coronaviruses. Here, we developed an mRNA vaccine expressing a stabilized spike protein derived from OC43 coronavirus and tested its efficacy in different challenge models in C57BL/6 mice . This novel OC43 vaccine elicited OC43-specific immune responses, as well as cross-reactive immune response against other embecoviruses , including HKU1 and mouse hepatitis virus (MHV-A59). Interestingly, this OC43 vaccine protected mice not only against a lethal OC43 infection but also against a distant embecovirus, MHV-A59. These findings provide insights for the development of common cold coronavirus vaccines, demonstrating their potential to protect against various c...

  Abstract Highly pathogenic avian influenza A(H5) viruses globally impact wild and domestic birds, and have caused severe infections in mammals, including humans , underscoring their pandemic potential . The antigenic evolution of the A(H5) haemagglutinin (HA) poses challenges for pandemic preparedness and vaccine design . Here the global antigenic evolution of the A(H5) HA was captured in a high-resolution antigenic map . The map was used to design immunogenic and antigenically central vaccine HA antigens, eliciting antibody responses that broadly cover the A(H5) antigenic space. In ferrets , a central antigen protected as well as homologous vaccines against heterologous infection with two antigenically distinct viruses. This work showcases the rational design of subtype-wide influenza A(H5) pre-pandemic vaccines and demonstrates the value of antigenic maps for the evaluation of vaccine-induced immune responses through antibody profiles. Source: Nature,  https://www.nature.c...

  Abstract Background Amid the declining clinical severity of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and diminishing public uptake of annual coronavirus disease 2019 (Covid-19) vaccines, contemporary evidence on vaccine effectiveness against clinically relevant outcomes is needed. Methods We conducted an observational study that used the electronic health records of the Department of Veterans Affairs to evaluate the effectiveness of the 2024–2025 Covid-19 vaccine among veterans who received the Covid-19 and influenza vaccines on the same day (164,132 participants) and in an active-comparator group of veterans who received the influenza vaccine only (131,839 participants), between September 3 and December 31, 2024. Participants were followed for 180 days or until the occurrence of an outcome, whichever came first. We used inverse-probability–weighted models to estimate vaccine effectiveness (calculated as 1 minus the risk ratio) against Covid-19–assoc...

  Highlights •  UniFluVec, an H1N1pdm vaccine candidate , includes NS1 and NEP modifications to boost attenuation and immunity. •  UniFluVec protects ferrets from H5N1 , enhancing clearance, limiting lung damage, and ensuring 100 % survival after one dose. •  Replication-deficient UniFluVec shows cross-protection , supporting its potential as a pre-pandemic intranasal vaccine. Abstract Background The emergence of new influenza strains with unpredictable antigenic properties poses a significant vaccination challenge. The increasing incidence of human H5 infections underscores the urgent need for effective pre-pandemic vaccines. Methods The UniFluVec and UniFluVec-wtNS1 viruses were designed as H1N1pdm vaccine candidates . Both viruses contained a heterologous A/Singapore/1/57-like (H2N2) NEP gene , which served as an attenuation factor . UniFluVec additionally carried a truncated to 124 amino acids NS1 gene , and an insertion of conserved influenza sequences. UniFluVe...

  Abstract In 2024, a human infection with clade 2.3.4.4b highly pathogenic avian influenza A(H5N1) virus was identified in the United States in an individual with no known exposure . Genetic analysis revealed two hemagglutinin (HA) substitutions, P136S and A156T, which may alter viral antigenicity . Virus isolation was unsuccessful, preventing timely serologic analysis. To overcome this limitation, we generated recombinant viruses by reverse genetics and characterized the effects of the substitutions on antigenicity, receptor binding , and replicative fitness. The A156T substitution introduced a potential N-linked glycosylation site , resulting in altered antigenicity and reduced replication in primary human nasal epithelial cells and ferrets . Importantly, the A(H5N1) candidate vaccine virus (CVV) IDCDC-RG80A, which possesses HA-T156, remained antigenically effective against viruses with and without these substitutions. These findings highlight the importance of sequencing, rever...

  The World Health Organization (WHO) emphasizes that there is currently no conclusive scientific evidence confirming a possible link between autism and use of acetaminophen (also known as paracetamol) during pregnancy.  Globally, nearly 62 million people (1 in 127) have autism spectrum disorder , a diverse group of conditions related to development of the brain . Although awareness and diagnosis have improved in recent years, the exact causes of autism have not been established , and it is understood there are multiple factors that can be involved.   Extensive research has been undertaken over the past decade, including large-scale studies, looking into links between acetaminophen use during pregnancy and autism . At this time, no consistent association has been established.  WHO recommends that all women continue to follow advice of their doctors or health workers, who can help assess individual circumstances and recommend necessary medicines. Any medicine sh...

  Abstract Since its discovery in U.S. dairy cattle in early 2024, the highly pathogenic H5N1 avian influenza (clade 2.3.4.4b) has spread widely among herds, causing major economic losses. This zoonotic event emphasizes the urgent need for H5 vaccines that elicit strong, durable, cross-reactive immune responses in cattle , especially young calves. To address this, we immunized mice and cattle with a centralized consensus H5 vaccine, designed to localize to the central node of the human H5 phylogenetic tree . The vaccine was delivered using serotype-switched adenoviral vectors in a prime:boost regimen , combined with intramuscular and intranasal coadministration to target systemic and mucosal immunity and elicit strong humoral and cellular immune responses. This approach strategically integrates multiple innovative features: centralized consensus immunogens, mucosal targeting, and vector serotype switching that are aimed at maximizing immune protection against H5N1 viruses . Our res...

  Abstract Global efforts to eradicate smallpox—an Orthopoxvirus infection—began in the mid-20th century, with the last naturally occurring case reported in 1977. This was achieved through global solidarity efforts that expanded the smallpox eradication vaccination program . Approximately 50 years following the cessation of mass smallpox vaccination and in the absence of access to a sustainable boosting program , the population immunologically naïve to Orthopoxviruses has increased significantly. With increasing global movements and travels, we argue that the emergence of two back-to-back yet distinct mpox epidemics in the 21st century is a sign of humanity’s lost herd immunity to Orthopoxviruses. This needs concerted efforts to restore. Source: Viruses,  https://www.mdpi.com/1999-4915/17/9/1257 ____

  ABSTRACT Influenza A viruses continuously circulate among avian and swine species, posing a persistent threat to public health . The development of influenza candidate vaccine viruses (CVVs) plays a pivotal role in the global strategy for influenza pandemic preparedness . Safety-testing of CVVs for attenuation in ferrets represents a critical step that takes place prior to making these viruses available to vaccine manufacturers . Development of pathogenicity standards is needed to establish acceptable thresholds of disease so that CVV safety can be assessed without the need for comparison to the parental virus. To assess the capacity of diverse CVVs to cause pathogenesis in mammalian hosts , clinical and virological parameters were compiled from CVV assessments in ferrets conducted using consistent methods over approximately 20 years to identify disease parameters most reflective of attenuation compared to wild-type strains. These analyses revealed an overall reduction in ferret ...

  Abstract Highly pathogenic avian influenza A(H5N1) clade 2.3.4.4b viruses have infected >1,000 herds of dairy cattle and hundreds of poultry flocks in the United States since the beginning of 2024. Seventy human cases have been reported during that period, mainly through occupational exposure . Although prior influenza A(H1N1)pdm09 virus infection has been shown to confer protection against influenza A(H5N1) clade 2.3.4.4b virus infection in the ferret model, it remains unclear if influenza vaccines , known to elicit a less potent and narrower cross-reactive immune response, can achieve a similar effect. In this article, we demonstrate that immunization with commercially available human seasonal influenza vaccines also confers partial protection against disease caused by H5N1 clade 2.3.4.4b virus in ferrets , which is partially associated with the presence of cross-reactive antibodies targeting H5N1 virus antigens. Source: US Centers for Disease Control and Prevention,  h...

  Abstract Since 2021, the panzootic of high pathogenicity avian influenza (HPAI) represents an increasing threat to wild vertebrate populations . In this context, recent vaccines developed for poultry could provide tools for the conservation of wild endangered birds populations . The king penguin (Aptenodytes patagonicus), a long-lived seabird breeding in dense colonies with an extended chick-rearing period , was identified as a possible surrogate species for a vaccination trial in a sub-Antarctic natural setting . We investigate here the immune response of king penguin chicks to a self-amplifying mRNA vaccine against a H5 HPAI clade 2.3.4.4b protein. Thirty chicks were vaccinated (primo- and boost-injections), 20 were kept as controls. Along 250 days of monitoring, vaccinated chicks showed a high and persistent immune response , granting a strong seroneutralisation capacity against the virus, up to fledging. No adverse effects were observed. The screening for antibodies against u...

  Abstract Background On September 27, 2024, Rwanda reported an outbreak of Marburg virus disease (MVD), after a cluster of cases of viral hemorrhagic fever was detected at two urban hospitals. Methods We report key aspects of the epidemiology, clinical manifestations, and treatment of MVD during this outbreak, as well as the overall response to the outbreak. We performed a retrospective epidemiologic and clinical analysis of data compiled across all pillars of the outbreak response and a case-series analysis to characterize clinical features, disease progression, and outcomes among patients who received supportive care and investigational therapeutic agents. Results Among the 6340 patients with suspected MVD who underwent testing, 66 had laboratory-confirmed MVD , 51 (77%) of whom were health care workers. The median estimated incubation period was 10 days (interquartile range, 8 to 13), and symptom onset occurred a median of 2 days (interquartile range, 1 to 3) before hospital ad...

  Abstract Risk of death for both mother and fetus following Ebola virus infection is extremely high . In this study, healthy women in Rwanda aged ≥18 years were randomized to two-dose Ebola vaccination (Ad26.ZEBOV, MVA-BN-Filo) during pregnancy (group A) or postpartum (group B). Unvaccinated pregnant group B women served as control. This was a parallel, randomized, controlled, open-label, single-center trial to evaluate the safety (primary endpoint—outcomes of interest and serious adverse events (SAEs)) and immunogenicity (secondary endpoint) of the two-dose Ebola vaccination. Among 3,484 women screened, 2,013 were randomized, and 2,012 women and 1,945 infants born alive were descriptively analyzed . Adverse outcomes of interest occurred in women ( 5.2% in group A and 7.3% in group B ) and infants ( 26.0% in group A and 25.6% in group B ). The most common maternal outcome of interest was pathways to preterm birth (3.2% in group A and 3.4% in group B), and the most common infant ou...

  Highlights •  The H5N1 influenza virus-like particle vaccines are prepared through baculovirus expression vector system. • In vitro assessments have confirmed that this VLP vaccine has the correct conformation and functional activity. • This VLP vaccine induces robust humoral and cellular immune responses in mice , and provides complete protection against infection with the matched strain. Abstract Avian influenza virus infections pose a potential pandemic threat . The currently licensed vaccines have inherent limitations, emphasizing the urgent need for improved influenza vaccines. Here, we developed a novel hemagglutinin (HA) virus-like particle (VLP) vaccine candidate through the baculovirus expression vector system (BEVS). The engineered VLPs incorporate HA from H5N1 and matrix 1 (M1) protein from H1N1 . Comprehensive characterization revealed that purified HA VLPs exhibited morphological fidelity to native influenza virions while maintaining key viral biological propert...

  Summary Background Influenza vaccination is widely recommended to prevent death and serious illness in vulnerable people , including those with heart failure . However, the randomised evidence to support this practice is limited and few people are vaccinated in many parts of the world. We aimed to determine whether influenza vaccination can improve the outcome of patients after an episode of acute heart failure requiring admission to hospital in China . Methods We undertook a pragmatic, multiregional, parallel-group, cluster (hospital)-randomised, controlled, superiority trial over three winter seasons in China. Participating hospitals were located in the counties of 12 provinces with the capability of establishing a point-of-care service to provide free influenza vaccination to a sufficient number of patients before their discharge, if allocated to the intervention group. No such service was used in hospitals allocated to usual care (control) but patients were informed of fee-fo...