Efficacy, immunogenicity, and safety of a cell culture-derived quadrivalent influenza vaccine compared with a non-influenza vaccine in infants and children across five influenza seasons: a phase 3, multinational, observer-blind, randomised controlled trial.

To examine the seasonal variation of invasive group A streptococcal infections (iGAS) in relation to respiratory viral circulation, with special reference to pandemic restrictions, and to assess whether increases in viral activity may explain recent increases in iGAS. We performed a time-series analysis using a multivariate negative binomial regression model, with weekly counts of respiratory virus detections as the independent variable and weekly counts of iGAS cases as the dependent variable, covering the period from January 2010 to December 2024. We found a significant association between influenza and iGAS, with increases in influenza activity followed by an increase in iGAS cases. The association was strongest at a 2-week time lag. Influenza A (incidence rate ratio 1.0050, P <0.001) and influenza B (incidence rate ratio 1.0133, P <0.001) were both independent predictors of the number of iGAS reported 2 weeks later. The proportion of iGAS cases related to influenza activity was 21.7% before and 23.4% after the pandemic. The iGAS incidence declined by 76% during the period of COVID-19 restrictions. Annual influenza epidemics appear to contribute to seasonal increases in iGAS cases. Preventive measures aimed at reducing influenza spread may have a potential to reduce iGAS incidence.

This study documents the association between computer skills/digital literacy and influenza vaccination take-up among older adults in Europe during and after the COVID-19 pandemic. Using data from the Survey of Health, Ageing and Retirement in Europe, we find a positive partial correlation between influenza vaccination take-up and two indicators of pre-pandemic computer skills/digital literacy, self-assessed pre-pandemic computer skills and having used a computer at work in any pre-pandemic job. We estimate also a positive partial association between increased digital skills during the pandemic and take-up decision. We show that increased digital skills is more likely among those having already better pre-pandemic computer skills, suggesting that the pandemic might have exacerbated inequalities in take-up due to a widening in the so-called digital divide.

Evaluation of immune protective efficacy of recombinant adenovirus vector vaccine containing RBS of influenza virus subtype H1N1.

Respiratory syncytial virus (RSV) is a common virus that causes respiratory infections, posing a serious threat, particularly to infants, the elderly, and individuals with compromised immune systems. As the leading cause of lower respiratory tract infections (LRTIs) in infants, RSV is responsible for millions of cases worldwide each year. Its incidence rises significantly during the winter influenza season. Despite decades of research, no effective vaccine exists, and antiviral treatment options remain limited, presenting a major challenge to global public health. With the advancement of emerging technologies, researchers have made significant progress in understanding the pathological and biological characteristics of RSV, the mechanisms of immune response, and its long-term health impacts. This review aims to provide a comprehensive overview of the basic biological characteristics, epidemiology, clinical manifestations, and diagnostic and therapeutic strategies of RSV and to explore preventive measures and future research directions, offering the latest scientific evidence for RSV prevention and control.

Background: There is a high burden of influenza among individuals aged 50–64 years, with the highest rates of influenza infections other than children. The MF59-adjuvanted influenza vaccine (adjuvanted trivalent influenza vaccine [aTIV]/adjuvanted quadrivalent influenza vaccine [aQIV]) is designed to enhance response to vaccination among older adults. Among those aged ≥65 years, adjuvanted vaccine (aTIV/aQIV) has shown to be 14% more effective than standard (TIV/QIV) vaccines. This modeling study aimed to estimate the potential public health impact of aTIV/aQIV over standard influenza vaccines (TIV/QIV) among individuals aged 50–64 years over five influenza seasons. Methods: A static compartmental model was developed based on a Centers for Disease Control and Prevention model. Model inputs included vaccine effectiveness, vaccine coverage, population counts and disease burden estimates. Additional burden averted (symptomatic cases, outpatient visits, hospitalizations, intensive care unit [ICU] admissions, and deaths) was expressed as total incremental cases averted between the vaccines. Sensitivity analyses explored the influence of uncertainties in model input on the results. Results: Across the influenza seasons evaluated, on average each 5% increase in the relative vaccine effectiveness (rVE) of aTIV/aQIV vs. QIV prevented an additional 172,738 symptomatic illnesses, 74,277 outpatient visits, 1832 hospitalizations, 343 ICU admissions, and 105 deaths. This corresponds to an average seasonal incremental burden averted of 15.2%, with a range of 5.9% to 37.2%. Deterministic sensitivity analyses revealed the greatest variability was tied to rVE and burden estimates. Probabilistic sensitivity analyses results were normally distributed. Conclusions: Individuals aged 50–64 years could benefit from use of aTIV/aQIV over TIV/QIV, with an average increase in the number of influenza outcomes prevented of 15.2% per 5% improvement in vaccine effectiveness.

Nursing home residents and health care personnel (HCP) are at increased risk for exposure to influenza; in addition, residents of nursing homes who acquire influenza are at increased risk for severe disease. The Advisory Committee on Immunization Practices recommends routine annual seasonal influenza vaccination for persons without contraindications, including HCP and those at increased risk for severe influenza. Nursing homes report influenza vaccination among residents and HCP to CDC's National Healthcare Safety Network. This report describes influenza vaccination coverage among nursing home residents and HCP working in nursing homes during the 2024-25 influenza season (October 1, 2024-March 31, 2025). At the end of the 2024-25 influenza season, influenza vaccination coverage was 61.3% among nursing home residents and 42.1% among HCP who work in nursing homes; coverage among HCP varied by employment type. This study is the first comprehensive, national assessment of influenza vaccination coverage among nursing home residents and HCP who work in nursing homes in the United States. Monitoring of influenza vaccination coverage in this population at high risk for influenza exposure and severe influenza disease, along with implementation of a combination of influenza vaccination, administration of influenza antiviral medications, and other recommended practices to control the spread and severity of influenza in nursing home settings, can help protect nursing home residents and HCP against severe influenza-associated outcomes.

Background and aims Seasonal influenza virus infections represent a global health threat, especially in high-risk groups, including patients with liver cirrhosis that are considered to be immunocompromised, in particular in decompensated stages. Although vaccination is the most cost-efficient tool to prevent infectious diseases, information about vaccine performance in these patients is scarce. This study aimed to dissect the immunological responses to seasonal influenza vaccines in patients suffering from compensated or decompensated liver cirrhosis. Approach and results Prospective, observational studies during the influenza seasons 2019-2020 (1 st season) and 2020-2021 (2 nd season) were performed. Participants received the WHO recommended seasonal tetravalent inactivated influenza vaccine. Samples taken before and after vaccination were subjected to in-depth analyses by serology, cytokine immunoprofiling, multi-parametric flow cytometry, and metabolomics. Patients with liver cirrhosis showed stronger vaccine-induced immune responses in comparison to healthy individuals, including hemagglutination-inhibiting and neutralizing antibodies. Furthermore, enhanced cell-mediated immune responses were observed in the cirrhosis patients as compared to healthy subjects after vaccination. Surprisingly, vaccination response was even stronger in more advanced, decompensated stages of liver cirrhosis. Distinct serum cytokine and metabolite profiles associated with systemic inflammation differentiated patients with decompensated from compensated cirrhosis as well as from the healthy individuals and were linked to vaccine response. Conclusion Patients with liver cirrhosis can mount an efficient response to seasonal influenza vaccines that is even superior in more advanced stages of cirrhosis. Systemic inflammation caused by liver cirrhosis may contribute to distinct humoral and cellular vaccine responses.

Seasonal influenza presents a persistent threat to global health, with the elderly (65 + years) facing disproportionate risks of severe clinical outcomes. While the World Health Organization advocates for targeted immunization, the epidemiological impact of varying vaccination schedules remains a critical area for quantitative evaluation. This study investigates how the prioritization and temporal shifting of vaccine administration influence disease burden within the demographic context of Korea. We constructed an age-structured compartment model across four demographic groups (G1:0-14, G2:15-49, G3:50-64, and G4: 65+) using 2023-2024 seasonal influenza data in Korea. Among the various scenarios evaluated, we specifically performed an analysis by advancing the vaccination start date for the elderly group (G4) by up to two weeks to evaluate its comparative effectiveness against the baseline Korean National Immunization Program (KNIP). Furthermore, to quantify parameter uncertainty and assess the robustness of our model, we performed bootstrapping and partial rank correlation coefficient (PRCC) analyses. Our analysis reveals that, under the baseline vaccination strategy, the highest infection rates occur in the G1 age group, while early vaccination of the G4 group is found to be effective in reducing hospitalizations and deaths. Specifically, scenarios prioritizing early vaccination for the elderly (G4) with different immune states were associated with a 34.2% reduction in cumulative cases (range: 11.5-53.9%) and a 39.1% decrease in peak infection levels (range: 12.3-60.4%) compared to the baseline. Sensitivity analysis using PRCC showed that the symptomatic infectious period and G4 transmission parameters were identified as the primary drivers of cases and deaths. These findings suggest that targeted, timely vaccination of the elderly (65 + years) can contribute to mitigating the overall epidemic burden and alleviating periods of high hospital demand. Our simulation results indicate that age-specific strategies, particularly those accelerating vaccination for the elderly, offer a valuable quantitative framework for reducing the public health impact of seasonal influenza. While these outcomes are subject to model-specific assumptions, they provide a reasonable basis for further refining immunization programs within structured epidemic interventions.

Antibodies against neuraminidase (NA) are an independent correlate of protection and the antigenic relatedness between H1N1pdm and H5N1 NAs suggests that seasonal influenza infection may provide cross-reactive immunity. In this study, recent H1N1pdm infection elicited modest NA-inhibiting (NAI) antibody responses against contemporary A/Victoria/4897/2022 (H1N1pdm) but strong responses against older A/California/7/2009 (H1N1pdm). Convalescent sera exhibited significantly higher cross-reactive NAI against clade 2.3.4.4b H5N1 (A/Texas/37/2024) than non-flu A patients, whereas H3N2 infection did not elicit such cross-reactivity. NAI titers were comparable between N1-California and N1-Texas but lower against N1-Victoria, indicating greater antigenic similarity between N1-California and N1-Texas. This was supported by stronger inhibition of N1-Texas by N1-California sheep antiserum compared with N1-Victoria sheep antiserum. Surprisingly, H1N1pdm-infected patients exhibited very low NAI against clade 2.3.2.1a H5N1 (N1-Bangladesh; GMT of 171 vs GMT 1159 for N1-Texas). Mouse antisera demonstrated reduced reciprocal inhibition between N1-Texas and N1-Bangladesh, consistent with their antigenic divergence. When four residues in N1-Bangladesh were substituted with their corresponding residues in N1-Texas, N1-Bangladesh antiserum showed reduced NAI, while N1-Texas antisera showed increased inhibition compared with wild-type N1-Bangladesh. This suggests that these amino acid differences are partially responsible for their antigenic divergence. Importantly, longitudinal analysis revealed that boosted cross-reactive NAI responses waned by day 90 post-infection, highlighting their limited durability. Together, these findings demonstrate that seasonal H1N1pdm infection can transiently boost cross-reactive NAI antibodies against clade 2.3.4.4b H5N1, but antigenic divergence in clade 2.3.2.1a limits cross-reactivity. As such, the impact of pre-existing antibody during an H5N1 outbreak is dependent on the infecting clade.

Short-term safety and reactogenicity of same-day COVID-19 and influenza vaccination in very old, community-dwelling adults.

Are We Prepared for the Upcoming Seasonal Influenza Epidemic?

ABSTRACT This paper examines the effects of state-level adult and child seasonal flu vaccination rates on hourly real wages for women. Using an IV method to address possible endogeneity, we find a significantly positive effect of adult vaccination on women’s wages. Furthermore, we show that this effect is stronger for working mothers in age groups 16–24 and 25–44, and those with younger children aged 6 months–12 years. We also find that children’s vaccination has a significantly positive effect on mothers’ wages and that this effect is stronger for women with younger children. The results also show that the positive effect is particularly larger for non-college educated women, aged 16–44 with at least one child. These effects are also stronger for mothers with younger children.

Trends in Pediatric and Adult COVID-19, Influenza, and Routine Vaccinations Administered in Retail Pharmacies 2015 through 2023, United States.

Background: During the flu season, there is an increase in absenteeism due to illness, a drop in productivity, and a greater risk of the virus spreading among workers. Thus, the Italian Ministry of Health recommends vaccination for essential service workers. The University of Salerno, in collaboration with the local health authority of Salerno, offers free vaccination to its employees. Methods: A public health methodology for seasonal influenza vaccination in the workplace is presented-specifically in the university setting-with the aim of identifying individual, contextual, and organizational elements of the model that have promoted vaccination uptake. An ad hoc questionnaire was used (October-December 2025) to survey 399 academic employees, investigating seasonal influenza vaccination in the following aspects: recent personal experiences, motivations, vaccination experiences at university, sources of information, considerations regarding national and local vaccination campaigns, and level of vaccine confidence (VCI). Results: Seasonal influenza vaccination at the University is appreciated for its compatibility with working hours (66.1%), the availability of a platform that allows flexible booking (56.9%), the perception of safety in the environment (31.6%), the fact that the vaccine is free (17.4%), and the involvement of office/laboratory colleagues (5%). Participants appreciate the model and would apply it to other vaccinations at the University and in other institutional settings. A significant relationship (F = 7.24; df = 1; p < 0.05) exists between confidence in the vaccine and the sense of security experienced when receiving the vaccine in the workplace. Data analysis was performed using the IBM SPSS v.28 software. Conclusions: The model proposed can be applied to other institutional contexts, simplifying and facilitating access to vaccines by implementing vaccination campaigns tailored to specific work environments.

Influenza vaccination rates remain low among primary school students and vary by school, even under the free School-Located Influenza Vaccination (SLIV) in Beijing, China. To improve influenza vaccination coverage, we developed multifaceted, enhanced SLIV (E-SLIV) strategies in response to factors that influenced the SLIV implementation. The E-SLIV strategies were proved with modest effectiveness in improving influenza vaccination uptake via a cluster randomized trial in the 2022-2023 influenza season. This paper reports the implementation outcomes and identifies influencing factors for the implementation of the E-SLIV strategies, which was conducted in the same settings. The E-SLIV intervention study involved 20 primary schools in Beijing, China, which were randomly allocated in a 1:1 ratio to the intervention (i.e., E-SLIV) or control (i.e., usual SLIV practice) groups in the 2022-2023 influenza season. This study applied a convergent mixed methods design to evaluate implementation outcomes specifically for 10 schools in the E-SLIV group. Quantitative data were collected from 39 implementers via a close-ended questionnaire and a project-specific implementation checklist, and from 915 parents via a close-ended questionnaire. Qualitative data were gathered from 18 implementers and 8 parents via semi-structured interviews. Quantitative descriptive and qualitative thematic analysis were applied, with findings integrated via joint display for meta-inference based on an evaluation framework that combines the Reach, Effectiveness, Adoption, Implementation, Maintenance (RE-AIM) framework with Normalization Process Theory (NPT). E-SLIV reached 1,172 of the 1,541 targeted students in 10 intervention schools, representing an intervention coverage rate of 76.1% (95% CI [74.0%, 78.2%]). Qualitative findings indicated that the E-SLIV strategies may have limited success in reaching those with social media information overload and those who were hesitant about influenza vaccination. All 10 schools adopted the overarching E-SLIV strategies, but insufficient priority and endorsement from school administrators may have hindered the consistent adoption of specific program components. Both quantitative and qualitative findings suggested the E-SLIV strategies were flexible with adequate resources, enabling good implementation of most intervention components. However, relationships, skills, contexts, and content integration needed strengthening, and implementation was limited by COVID-19 related workload and vaccination uncertainty, and vaccine shortage, as the qualitative findings indicated. Around 83.3% (95% CI [73.4%, 93.2%]) of school implementers and 70.4% (95% CI [67.4%, 73.4%]) of parents favored maintaining E-SLIV. The multifaceted E-SLIV strategies reached most target populations and were well-implemented with high fidelity by most schools. The E-SLIV strategies strengthened collaboration, enhanced capacity, and provided tailored education, yet faced challenges including entrenched parental views, social media information overload, inadequate school leadership, low proactivity among school doctors in coordinating vaccinations, the COVID-19 pandemic, and temporary vaccine shortages. Findings inform future optimization of school-based vaccination programs and present a compelling case for measuring implementation outcomes using mixed methods.

Infectious disease forecasting is important to public health decision-making, particularly for mitigating the burden of seasonal influenza. We propose and evaluate comprehensive autoregressive modelling approaches (autoregressive integrated moving average (ARIMA) and autoregressive integrated moving average with exogenous variables (ARIMAX)) for short-term forecasts of influenza-related hospitalizations across the contiguous United States (US). We used data from the National Healthcare Safety Network to forecast the influenza seasons of the years 2022 to 2024 in 48 states. We compare automatically tuned models (AUTO) and ensembles of different sizes (ES27 or ES64). Base models are ARIMA models or ARIMAX models using forecasting covariates with a one-week lag of the forecast day, including: mean temperature, mean hospitalizations by epidemiological weeks, mean hospitalizations in adjacent states and the average of hospitalizations across the contiguous US. We also investigated the effect of forecasting based on log-transformed hospitalizations data and back-transforming the results (LB). Overall, 29 approaches were compared to the AUTO ARIMA model without logarithmic transformation and the FluSight baseline using weighted interval scores. Our results indicate that using the LB approach, which forecasts based on epidemic growth rate and back-transform the results, most increased model performance. The average of hospitalizations across the contiguous US (AVG) forecasting feature was the most useful covariate. Ensemble approaches typically did not improve performance. The best model was the AUTO ARIMAX using the AVG covariate with log-back transformation.

Background Rothia is an oral commensal bacterium increasingly detected in the respiratory tract, and recent studies have highlighted changes in its abundance in respiratory infections. Objective This study aimed to investigate the species distribution of Rothia, its co-occurrence with respiratory pathogens, and the immune alterations associated with Rothia co-infection in respiratory infections. Design We developed real-time PCR to differentiate R. aeria, R. dentocariosa, and R. mucilaginosa. Sputum samples from 447 hospitalized patients were tested for 35 respiratory pathogens and three Rothia species using customized TaqMan Array Card. Co-infection murine models were established. Results All three Rothia species were frequently detected (39.4% to 72.3%). R. mucilaginosa showed positive associations with SARS-CoV-2 among patients with respiratory symptoms (odds ratio 4.0, p < 0.0001) or pneumonia (OR 2.7, p = 0.019) and influenza A virus (IAV; OR 8.4, p = 0.004) in patients with pneumonia during an influenza season, but was negatively associated with Klebsiella pneumoniae (OR 0.3, p < 0.05). These inverse associations were confirmed in murine models. Increased mortality and bacterial burden were observed in IAV and R. mucilaginosa co-infection, while K. pneumoniae and R. mucilaginosa co-infection was attenuated. Both models showed increased neutrophils. Functionally, IAV co-infection impaired bactericidal activity whereas prior K. pneumoniae exposure enhanced bacterial clearance. Conclusions This study uncovers distinct pathogen associations of Rothia in respiratory infections, which may provide evidence for their roles in shaping disease outcomes.

The Influenza B virus (IBV), which accounts for nearly a quarter of annual global influenza-associated morbidity, represents a major human respiratory pathogen. Since late 2019, IBV transmission patterns have shifted markedly following the emergence of COVID-19, yet systematic studies on IBV prevalence before and after the pandemic remain limited. We conducted systematic surveillance of 66 IBV isolates collected from Guangzhou during 2022-2023. Phylogenetic analysis of HA/NA genes was complemented with evolutionary rate estimation, hemagglutination inhibition assays, antigenic cartography, and structural modeling of hemagglutinin variants. We revealed the distinct epidemic trends of IBVs in Southern China: clade V1A.3a.1/V1A.3a.2 co-circulated in 2022-2023 influenza season, while complete replacement of V1A.3a.1 by V1A.3a.2 in 2023-2024 season, which was driven by a 1.36-fold increase in the evolutionary rate of the HA gene (1.632 × 10-3, P < 0.05) post-NPIs. Spatially, discrete Bayesian phylogeographic analysis confirmed that Jiangxi Province acted as the core upstream hub of the nationwide transmission of V1A.3a.1, which persisted endemically from Jiangxi in 2020 to six adjacent provinces in 2021 before its final extinction in China. Notably, cross-reactive HI and quantitative antigenic cartography elucidated antigenic divergence between V1A.3a.1 and V1A.3a.2 subclades, and revealed that the complete displacement of V1A.3a.1 by V1A.3a.2 was mediated by the broadened antigenic recognition of 2023 V1A.3a.2 isolates. Structural modeling revealed L144P in the 150-loop may be the primary driver of antigenic divergence, inducing conformational rearrangement in residues 146-148. This study elucidates the unique evolutionary and epidemic patterns of IBV in the subtropical region of southern China after the relaxation of COVID-19 NPIs, deciphers the molecular mechanism of clade replacement and antigenic diversification of the Victoria lineage V1A.3a subclade, and validates the sustained effectiveness of the WHO 2022 influenza B vaccine strain update in southern China. Our findings fill the gap in systematic surveillance of IBV in subtropical sentinel regions, identify Guangzhou as a key monitoring site for IBV evolutionary dynamics, and provide critical molecular and antigenic evidence for the optimization of regional influenza surveillance systems and vaccine strain selection strategies.

Influenza vaccination is recommended to prevent influenza in patients with kidney failure. It remains unclear whether newer, enhanced vaccine formulations are more effective than standard-dose, egg-based, inactivated influenza vaccine (standard-dose vaccine) in patients undergoing dialysis. We sought to compare the effectiveness of five influenza vaccine formulations among patients undergoing dialysis. Using the United States Renal Data System database, we performed an active comparator cohort study among adults ≥65 years with kidney failure undergoing hemodialysis (2011/12 to 2019/20 influenza seasons) who received a standard-dose, high-dose, cell culture-based, adjuvanted, or recombinant influenza vaccine within a given season. We compared the risk of influenza-like illness, influenza, influenza-related hospitalization, severe influenza, and all-cause mortality during the influenza season by vaccine formulation. Season-specific risk differences and relative vaccine effectiveness (rVE) were estimated using propensity score-weighted Kaplan-Meier functions, accounting for the competing risk of death (for non-mortality outcomes). We combined the season-specific estimates via a random effects meta-analysis. 578,232 influenza patient-seasons included standard-dose vaccine (n=372,907), high-dose vaccine (n=192,880), cell culture-based vaccine (n=8,177), adjuvanted vaccine (n=3,308), or recombinant vaccine (n=960). Season-specific and meta-analytic estimates were consistent with a modest protective effect of high-dose vaccine versus standard-dose vaccine for influenza (meta-analytic rVE 5.1%; 95% CI, -0.7% to 10.5%), influenza-related hospitalization (meta-analytic rVE 5.5%; CI, -1.8% to 12.3%), and severe influenza (meta-analytic rVE 13.7%; CI, -9.7% to 32.1%), but not influenza-like illness or mortality. Patterns were similar for cell culture-based vaccine versus standard-dose vaccine (e.g., meta-analytic rVE for influenza, 18.3%; CI, 2.2% to 31.7%). Estimates for adjuvanted or recombinant versus standard-dose vaccines were imprecise. Quantitative bias analyses did not indicate residual confounding, although some estimates were imprecise. Among older adults undergoing dialysis, high-dose vaccine and cell culture-based vaccine may provide modestly increased protection versus standard-dose vaccine.