Search Results (510)

Background: Following the coronavirus disease 2019 (COVID-19) pandemic, increased reports of severe acute hepatitis of unknown etiology in children have raised concerns about virus-associated liver injury. Acute respiratory tract infections (ARTIs) are a common cause of pediatric hospitalization and may be accompanied by reactive hepatitis; however, virus-specific patterns of hepatic involvement remain incompletely defined. This study aimed to evaluate liver involvement associated with ARTIs in hospitalized children. Methods: This retrospective study included pediatric patients (<18 years) hospitalized with ARTIs between October 2021 and May 2023. Respiratory viruses were identified via multiplex real-time polymerase chain reaction assays. Liver function tests were systematically evaluated during hospitalization. Transaminase elevations were categorized according to the upper limit of normal (ULN = 40 U/L). Acute hepatic failure was defined according to the Pediatric Acute Liver Failure criteria. Results: A total of 179 patients were analyzed (median age: 38 months; 59.2% male). Elevated AST and ALT levels were observed in 24.0% and 8.4% of patients, respectively. Adenovirus was the most frequently detected virus (11.2%), followed by influenza A (7.3%) and parainfluenza virus (6.7%). Severe transaminase elevations (>5 × ULN and >500 U/L) were observed in patients with influenza infection. All cases of acute hepatic failure (n = 3) were associated with influenza infection. Other respiratory viruses were associated with mild or transient liver enzyme abnormalities. Conclusions: Severe hepatic involvement—including severe transaminase elevation and acute hepatic failure—occurred exclusively in children with influenza infection, particularly influenza B, while mild and transient liver enzyme abnormalities were common across other respiratory viral infections. These findings highlight the importance of targeted liver function monitoring in pediatric influenza patients and provide clinically relevant data on virus-specific hepatic involvement in the post-COVID-19 era. Full article

Background: China’s influenza vaccine (InfV) has undergone multiple iterations and numerous technological breakthroughs, providing tremendous impetus and solid support for the development of China’s health sector. As the number of vaccinated individuals continues to rise, the importance of ongoing surveillance and evaluation of vaccine safety has become increasingly prominent, forming part of efforts to maintain public trust in the national immunization program and ensure its sustainability. Methods: From 2016 to 2025, data on suspected adverse events following immunization (AEFIs) related to InfV administration were extracted from the Chinese National Immunization Information System (CNIIS). Data on InfV vaccination doses were obtained from the Anhui Provincial Immunization Information Management System. A descriptive statistical method was used to analyze the distribution characteristics of AEFIs, and the chi-square test was applied to evaluate differences in reporting rates. Results: Between 2016 and 2025, a total of 4026 AEFI reports related to InfV were monitored through the CNIIS. The overall reporting rate was 34.40 per 100,000 doses. Specifically, common adverse reactions and rare adverse reactions accounted for 95.88% (3860 cases) and 3.38% (136 cases), with reporting rates of 32.98 per 100,000 doses and 1.16 per 100,000 doses, respectively. Among common adverse reactions, the reporting rates of fever (axillary temperature ≥ 38.6 °C), local redness and swelling at the injection site (diameter > 5.0 cm), and local induration (diameter > 5.0 cm) were 9.62 per 100,000 doses, 1.96 per 100,000 doses, and 1.20 per 100,000 doses, respectively. Among rare adverse reactions, the reporting rates of allergic rash, angioedema, anaphylactic shock, febrile convulsions, anaphylactoid purpura, thrombocytopenic purpura, epilepsy, Guillain–Barré syndrome, and aseptic abscess were 0.98, 0.05, 0.03, 0.03, 0.02, 0.02, 0.01, 0.01, and 0.01 per 100,000 doses, respectively. No cases were reported for subunit inactivated influenza vaccine (IIV, Subunit). Statistically significant differences were observed in the reporting rates of allergic rash across different types of InfV (χ² = 36.83, p < 0.05), with trivalent inactivated influenza vaccine (IIV3, Split) and trivalent live attenuated influenza virus vaccine (LAIV3) showing the highest reporting rates. Most adverse events following vaccination occurred within 24 h after inoculation. Conclusions: From 2016 to 2025, the overall reporting rate of AEFIs after InfV administration in Anhui Province was within an acceptable range. Common adverse reactions were common, while rare adverse reactions were few, mainly consisting of allergic reactions. These results indicate that InfV has a favorable safety profile, and continuous strengthening of AEFI surveillance for InfV and improvement of surveillance quality are warranted. Full article

Background/Objectives: Re-emergence of Haemophilus influenzae serotype b (Hib) was reported in several European countries. We aimed to characterize the age distribution of H. influnezae carriage before and after Hib vaccination. Methods: We conducted a systematic review and meta-analysis to reassess H. influenzae carriage dynamics in the pre- and post-Hib vaccination eras, focusing on age-specific patterns in childhood. Searches were performed with no date restriction and included PubMed/MEDLINE, Scopus, Web of Science, WHO Global Index Medicus, and the Cochrane Library. Eligible studies reported nasopharyngeal and/or oropharyngeal carriage prevalence and serotype distribution. Pooled estimates with 95% confidence intervals (CIs) were calculated using random-effects models, with age-stratified analyses. Results: Twenty-two studies were included (12 pre- and 10 post-Hib vaccination). Pre-vaccination, pooled H. influenzae carriage prevalence was 24.3% (95% CI, 18.9–30.7%), including 6% (95% CI, 3.4–12.8%) for Hib and 17.5% (95% CI, 12.6–23.9%) for non–type b strains. Post-vaccination, overall carriage remained similar (21.8%; 95% CI, 14.6–31.2%), but Hib carriage declined markedly to 0.67% (95% CI, 0.26–1.71%), while non–type b strains predominated (16.7%; 95% CI, 10.4–25.6%). Meta-analysis showed that carriage peaked around 4–5 years of age and persisted into later childhood. Conclusions: Hib vaccination has reduced Hib carriage, but overall H. influenzae carriage persists due to non–type b strains. Age-related persistence of carriage may have implications for herd protection, particularly in the context of evolving vaccination schedules with early childhood boosters. Continued surveillance integrating carriage and immunological data is needed to inform optimization of vaccination strategies. Full article

Background/Objectives: The trajectory of influenza hospitalization burden from pre-COVID-19 pandemic baseline through post-pandemic recovery remains poorly characterized at the national level. This study characterized phase-stratified burden and seasonal structure, quantified racial and ethnic disparities, and assessed whether post-pandemic seasons represent anomalous departures from pre-pandemic expectations. Methods: Sixteen complete seasons of FluSurv-NET surveillance data (2009–2010 through 2024–2025; 509 observation weeks) were analyzed across pre-pandemic, disruption, and recovery phases using OLS regression with effect-size estimation, bootstrapped age-adjusted rate ratios, seasonal-trend decomposition (STL), Prophet time-series forecasting, and Isolation Forest anomaly detection. Results: Mean peak weekly hospitalization rate nearly doubled from pre-pandemic to recovery (5.1 to 11.1 per 100,000), cumulative seasonal burden increased from 46.3 to 87.0 per 100,000, and median peak timing advanced from MMWR week 9 to week 50. STL decomposition revealed a marked shift from weak pre-pandemic seasonality (Fs = 0.14) to substantially stronger annual regularity (Fs = 0.98) across three recovery seasons, with threefold amplitude increase. Non-Hispanic Black persons had rate ratios of 1.72, 2.16, and 1.99 relative to White persons across phases; American Indian and Alaska Native persons showed the highest disruption-phase ratio (2.24, 95% CI 1.90–3.53), based on two contributing seasons. A flat-growth Prophet model detected first exceedance in February 2020, outperforming a linear-growth specification on held-out validation. Isolation Forest identified 2017–2018, 2023–2024, and 2024–2025 as robust anomalies across all contamination thresholds. Conclusions: Post-COVID-19 pandemic influenza recovery is characterized by intensified and restructured seasonality, persistent racial and ethnic disparities, and anomalous burden exceeding pre-pandemic projections, identified independently by time-series forecasting and unsupervised anomaly detection. Full article

Background: Non-pharmaceutical interventions during the COVID-19 pandemic altered respiratory pathogen circulation, and a bacterial rebound followed once restrictions were lifted. We describe pediatric pneumococcal respiratory infections and their bacterial co-detections in the immediate post-pandemic period. Methods: We retrospectively analyzed respiratory specimens from children aged 0–18 years tested with a multiplex real-time PCR panel (Allplex Respiratory Panel, Seegene, Seoul, South Korea; seven bacterial pathogens) restricted to this predefined bacterial spectrum at a tertiary pediatric hospital in Galați, Romania, during 2022 and 2023. A total of 2546 panels were performed in 2022 and 3250 in 2023, allowing pneumococcal positivity rates to be calculated. Proportions are reported with Wilson 95% confidence intervals; associations were tested with Pearson chi-square and Fisher exact tests in SPSS v.23. Results: Children with detected Streptococcus pneumoniae rose from 100 to 415, corresponding to a rise in pneumococcal positivity from 3.9% (100/2546) to 12.8% (415/3250). Among the positive children, pneumococcus–Haemophilus influenzae co-detection increased from 33.0% to 45.1% (odds ratio 1.63, 95% CI 1.02–2.61; p = 0.029), while pneumococcus alone fell from 60.0% to 50.1%. Boys, urban residence, and early childhood predominated, and community-acquired pneumonia diagnoses rose from 61 to 214. No profile–demographic association reached significance (panel–residence 2023, p = 0.063). Conclusions: A post-pandemic rise in pediatric pneumococcal detections and increasing H. influenzae co-detection were observed, supporting syndromic multiplex PCR in rapid pediatric diagnostics and antimicrobial stewardship. Full article

To address the lack of a commercially available vaccine for goose circovirus (GoCV), we developed and evaluated a prokaryotically expressed subunit vaccine targeting the viral capsid (Cap) protein. A truncated Cap protein (GoCV-ΔCap) was expressed in Escherichia coli (E. coli) and formulated with aluminum hydroxide as a subunit vaccine (GoCVsubvac). Goslings were primed intramuscularly (i.m.) with high (75 µg) or low (15 µg) doses GoCVsubvac, followed by a boost 14 days later. At 14 days post-boost, goslings were challenged with GoCV and were administered a bivalent inactivated vaccine against Newcastle disease virus (NDV) and H9-subtype Avian influenza virus (AIV). Using our established gosling pathogenicity model, vaccine efficacy was evaluated via body weight, lesions, viral load, antibody titers, cytokine responses, and interference with NDV/AIV immunity. Results demonstrated that the GoCV-ΔCap vaccine, especially the high-dose formulation, provided effective immunoprotection. It elicited robust humoral and cellular immune responses, reduced lymphoid pathology, and decreased the viral detection rate in lymphoid tissues from 100% (5/5) in infected controls to 40% (2/5). Importantly, it alleviated GoCV-induced immunosuppression and preserved the immunogenicity of co-administered vaccines. This novel subunit vaccine is a promising candidate for controlling GoCV disease (GoCVD). Full article

Background: Vaccination coverage declined in many countries during the COVID-19 pandemic, including in Bosnia and Herzegovina. We evaluated a telephone-based outreach intervention implemented in primary healthcare facilities (PHCs) in the Federation of Bosnia and Herzegovina. The intervention targeted missed routine vaccinations among children aged 0–7 years. Method: Using a programmatic, non-randomized pre–post design, healthcare teams reviewed registries to identify under-vaccinated children, and parents were contacted by phone to facilitate catch-up visits. Results: Among age-eligible children, vaccination coverage increased from 66.5% to 74.2% for measles–mumps–rubella (MMR) dose 1, from 43.4% to 51.7% for MMR dose 2, and from 50.4% to 55.9% for the fourth dose of diphtheria–tetanus–acellular pertussis-inactivated poliovirus–Haemophilus influenzae type b vaccine (DTaP-IPV-Hib). Mixed-effects models adjusting for age, sex, and clustering by facility and canton showed higher odds of vaccination post-intervention for MMR dose 1 (adjusted odds ratio [aOR] 1.65), MMR dose 2 (aOR 1.61), and DTaP-IPV-Hib dose 4 (aOR 1.39; all p < 0.001). Conclusions: These results show that registry-based, proactive outreach can yield significant improvements in routine childhood vaccination coverage in real-world settings and may be a scalable approach for decentralized health systems recovering from pandemic disruptions. Full article

Seasonal influenza circulation was profoundly disrupted during the COVID-19 pandemic, resulting in an unprecedented global decline in viral activity and genetic diversity. As non-pharmaceutical interventions gradually relaxed, influenza viruses re-emerged in multiple regions in 2022; however, genomic data from Latin America remain limited, particularly for the first post-pandemic season. In this study, we analyzed the epidemiological, genomic, and evolutionary patterns of influenza A and B viruses circulating in Mexico between June 2018 and June 2023, with a specific focus on the first post-pandemic season (June 2022–June 2023). More than 90% of the influenza virus genomes available from Mexico for this post-pandemic period were generated in this study, while data from earlier seasons were used for contextualization. Following a near-complete absence of influenza circulation during 2020–2021, viral activity re-emerged in late 2021 and intensified during 2022–2023. Post-pandemic circulation in Mexico was dominated by influenza A(H3N2), with a lower contribution from A(H1N1)pdm09 and a delayed re-emergence of B/Victoria; B/Yamagata was not detected. Genomic analyses revealed rapid lineage turnover after the pandemic, characterized by the predominance of post-pandemic clades and reduced genetic diversity compared with pre-pandemic seasons. Phylogenetic analyses indicated multiple introductions and strong regional connectivity across North and South America. Full article

The global emergence of the avian influenza virus (AIV) H5N1 clade 2.3.4.4b since 2016 has caused substantial losses in wild bird and poultry populations, along with heightened risks of transmission to humans and other mammals. Vaccination of poultry has been a key strategy to curb the virus’s spread and mitigate its socioeconomic impact. This report describes an outbreak of high pathogenicity avian influenza virus (HPAIV) H5N1 clade 2.3.4.4b in a flock of 15,000 brown layer chickens (170 days old), all of which had received a four-dose vaccination regimen with H5N1/H5N8 commercial vaccines at 17, 50, 100, and 125 days of age. Despite this vaccination history, H5N1 infection was confirmed approximately seven weeks post-vaccination. H5N1 infection was confirmed by RT-qPCR, virus isolation, and full genome sequencing covering all eight gene segments, followed by phylogenetic and molecular analyses. Clinical signs included reduced feed intake, decreased egg production, and a cumulative mortality rate of 35% over 52 days. Hemagglutination inhibition (HI) testing with various H5 antigens revealed inconsistent antibody titers (geometric mean: 4.0 to 9.1 log2). Genetic analysis of the full-length HA and NA gene sequences further revealed strong similarity to contemporaneous H5N1 clade 2.3.4.4b strains circulating in Egypt, with multiple mutations in the HA head domain, particularly near immunogenic epitopes and receptor binding sites. These findings highlight the limitations of current vaccination strategies under conditions of antigenic mismatch and complex immunization schedules, emphasizing the need for improved vaccine matching and continuous molecular surveillance. To improve outbreak management in poultry, enhanced vaccination protocols, stringent biosecurity measures, and rigorous monitoring practices are critical. Full article

Background and Objectives: New Caledonia, an archipelago in the South Pacific, experienced an unprecedented conjunction of prolonged border closure during the COVID-19 pandemic (2020 to 2022) and marked influence of the El Niño/Southern Oscillation (ENSO). This context provided a unique opportunity to explore how environmental drivers, island isolation, and socio-demographic factors interact to shape infectious disease dynamics. This study aimed to assess the respective and combined effects of climatic variability, travel restrictions, and socio-demographic factors on the dynamics of four priority infectious diseases. Materials and Methods: We retrospectively analysed data from 2017 to 2023 on four infectious diseases: leptospirosis, dengue, influenza, and hepatitis A (HAV). Satellite precipitation data and the Multivariate El Niño/Southern Oscillation Index (MEI) were used. Socio-demographic and economic variables were gathered. Statistical analyses employed descriptive analysis and Generalized Additive Mixed Models to evaluate the associations between climatic events, travel restrictions, and disease circulation using the communal level as a random effect and time (daily) as a spline effect. Results: We analysed 878 cases of leptospirosis, 165 of HAV, 6607 of influenza, and 7377 dengue cases. Influenza was associated with rainfall before lockdown (Odds Ratio (OR) 0.7, Confidence interval 95%, (CI95%), (0.6–0.8)) and disappeared during lockdown but resurged post-reopening losing its meteorological association. Dengue epidemics declined, coinciding with the Wolbachia program and border closure, and were associated with lower MEI (OR 0.78, CI95% (0.6–1) during the 2017 to 2020 period. HAV cases were correlated with the MEI (OR: 1.8, CI95% (1–3.3)). Leptospirosis cases were associated with cumulative rainfall (OR 1.12 (1.1–1.2)) and lower education (OR 1.04, CI95% (1–1.1)) and decreased with water supply (OR 0.7, CI95% (0.5–0.8)). Conclusions: Our findings highlight how climatic conditions, mobility restrictions, and socio-environmental inequities differentially shape infectious disease risks in island ecosystems. These results reinforce the need for integrated One Health surveillance that jointly addresses environmental change, social vulnerability, and infectious disease prevention. Full article

Background/Objectives: Primary Care Physicians (PCPs) are widely regarded as trusted sources of health information and can play a pivotal role in increasing seasonal influenza vaccination (SIV) within their communities. We aimed to explore PCPs’ attitudes toward SIV and their views regarding proposed strategies to enhance SIV uptake in the evolving post-pandemic landscape. Methods: A qualitative study utilizing semi-structured individual interviews with a nationwide sample of 25 PCPs was conducted. Results: Physicians’ attitudes toward SIV were overwhelmingly positive; they recognized its protective value for individuals and the community alike, its efficacy in averting serious illness, and its proven safety profile. Regarding strengthening SIV uptake, PCPs positively appraised the following strategies: (a) viewing all clinical encounters as opportunities for vaccination; (b) outsourcing vaccination to nursing, allied health staff and community pharmacists, provided that specific prerequisites are met; (c) forwarding personalized notifications to health providers and (d) the public; and (e) establishing at-home vaccinations. Financial incentives would reportedly act as tangible acknowledgement and motivate PCPs to work toward primary prevention. However, others have argued that SIV is inherently embedded in their duty as PCPs, and potential remunerations would dwindle the public’s confidence in PCPs. Establishing incentives for the general population reportedly minimizes confidence and the perceived value of SIVs and was assessed to be ineffective in the Greek context. Promoting SIVs through video games was considered to be less effective for the adult population. Conclusions: Mapping PCPs’ insights is key in designing effective SIV strategies that are concurrent with communities’ values, needs, and learnt experience from the COVID-19 pandemic. Full article

Background/Objectives: We still do not clearly know whether COVID-19 continues to impose a greater clinical burden than influenza in the “post-pandemic” era. Our study quantified and compared monthly COVID-19 and influenza hospitalization incidence among adult subgroups from October 2022 through December 2024. We assessed vaccine coverage trends and examined vaccination status among those hospitalized. Methods: Using the Veradigm linked claims and electronic health record dataset, we conducted a non-interventional, retrospective cohort study; three monthly cohorts included individuals aged 65+, high-risk (HR) adults (defined as adults 18+ with HR conditions and/or aged 65+), and adults aged 50–64 years who were enrolled with both medical and pharmacy coverage. We estimated monthly cumulative incidence of COVID-19 and influenza-related hospitalizations, vaccination coverage rates, and the proportion of hospitalized individuals who had received yearly updated vaccines. Results: COVID-19 hospitalizations consistently exceeded those of influenza across months and populations. Among adults aged 65+, COVID-19 hospitalization rates were 2–3 times higher than influenza in winter and 20–30 times higher during off-season months, with similar trends observed in high risk adults. COVID-19 incidence surged in summer, while influenza remained seasonally confined. Vaccination coverage for influenza peaked near 50% annually; COVID-19 coverage was lower, peaking at ~26% by December each year. Most hospitalizations occurred among unvaccinated individuals, particularly for COVID-19. Conclusions: COVID-19 continues to impose a substantial, year-round burden, particularly in older and high-risk adults, exceeding that of influenza. The high proportion of unvaccinated hospitalizations highlight a critical gap in prevention efforts and underscore the need for improved public health messaging and vaccine adoption. Full article

American Indian and Alaska Native (AI/AN) communities experienced disproportionate COVID-19 morbidity and mortality, particularly in rural areas with limited public health infrastructure. This study examined primary COVID-19 information sources among AI/AN adults in rural Michigan and evaluated how trust in these sources relates to health knowledge, attitudes, and vaccination behaviors. We conducted a prospective, randomized pre-post interventional study among 273 adults at a tribal health clinic in rural Isabella County, Michigan (2022–2024). Participants were assigned to receive a culturally tailored educational video or infographic, and surveys assessed COVID-19 knowledge, vaccine attitudes, information sources, and perceived reliability. Social media was the most frequently used information source but was rated as less reliable, whereas healthcare workers (HCWs) were considered the most trusted. Reliance on HCWs and personal relationships was associated with higher baseline vaccine knowledge and greater uptake of influenza vaccination. Both educational formats resulted in modest improvements in COVID-19 knowledge and vaccine attitudes. While no consistent differences were observed between formats overall, infographic-based education was associated with greater gains in select vaccine knowledge domains among participants who relied on trusted interpersonal or clinical information sources. These findings highlight a “usage-trust gap” in rural AI/AN health communication, where frequently used information channels are not necessarily the most trusted. Culturally tailored messaging delivered through trusted clinical and interpersonal networks may enhance the effectiveness of public health communication and support vaccine uptake in underserved communities. Full article

The effectiveness of infection prevention depends on not only uptake but also the timing of adoption. Vaccination studies typically treat uptake as binary, overlooking when while investigating why individuals get vaccinated. Using the novel mRNA COVID-19 vaccines as a case study, the influences of risk perceptions and social norms on vaccination timing were examined through an Innovation Diffusion framework. An online survey was conducted in November 2021 to assess vaccination behaviors, attitudes, and peer expectations of 1710 U.S. residents (51.64% females, 31.23% minorities, with a relatively balanced distribution across age and income brackets). Participants were classified by vaccination timing and intentions as early adopters, early majority, late majority, or laggards for comparative analyses. One year after vaccine rollout, 64.3% had received at least one dose; 20.1% reported no intention to vaccinate, and this resistance persisted through May 2023 when the pandemic ended. Vaccine confidence and prior behavior (e.g., influenza vaccination) demonstrated strong gradients across adoption timing. Earlier uptake was associated with higher perceived vaccine importance, infection risk, and peer uptake, whereas age and education effects diminished over time. Perceived illness severity and disease knowledge showed inconsistent influences. Later adopters anticipated higher post-vaccination infection risk and greater peer non-vaccination, reinforcing hesitancy. Social norms (but not risk perception) mediated the relationship between confidence and timing; earlier adoption further predicted booster acceptance. These findings highlight the importance of trust, correcting efficacy misperceptions, and leveraging positive peer norms to promote timely vaccination and inform strategies for other infectious diseases. Full article

Background: Acute lymphoblastic leukemia is the most prevalent childhood cancer and the leading cause of cancer mortality before the age of 20. Although therapeutic advances have significantly improved survival, children and adolescents treated for acute lymphoblastic leukemia remain vulnerable to infections, largely preventable by vaccination, due to humoral and cellular immune dysfunction induced by disease and treatment. Materials and Methods: This systematic review, based on electronic databases, aims to evaluate antibody levels associated with potential protective immunity against vaccine antigens for diphtheria, pertussis, tetanus, poliomyelitis, Haemophilus influenzae type b, measles, mumps, rubella, influenza, varicella-zoster virus, yellow fever, pneumococcal, and meningococcal diseases in children and adolescents treated for acute lymphoblastic leukemia after completion of chemotherapy. Results: A total of twenty-four studies published between 1981 and 2023 were included, comprising 1110 children and adolescents. Protective antibody levels ranged from 11% to 97% for diphtheria, 0% to 90% for pertussis, 20% to 100% for tetanus, and 11% to 95% for poliomyelitis. Haemophilus influenzae type b, protection ranged from 16.7% to 100%. Viral vaccines also showed heterogeneous responses, with protection rates of 25–79% for mumps, 16–86% for measles, 35–98% for rubella, and 23–75% for varicella-zoster virus. Antibody responses to pneumococcal and meningococcal vaccines were consistently low, with protection rates of 5–38% for pneumococcal studies and 12% in a single meningococcal study. Conclusions: This review found a consistent and clinically relevant loss of vaccine-induced immunity in children and adolescents treated for acute lymphoblastic leukemia. The recommendation of vaccine booster doses for this vulnerable population, irrespective of serological status, may represent a more practical approach to ensuring adequate post-chemotherapy treatment protection. Full article