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Abstract Background Influenza remains a global public health concern. Understanding the vaccination-induced response in an aging population, which is susceptible and at high risk, is essential for disease prevention and control. Here, we report findings on the safety and immunogenicity of a quadrivalent influenza split-virion vaccine (15 µg/subtype/0.5 ml/dose) (hereinafter referred to as the “quadrivalent influenza vaccine”) in a population aged ≥ 60 years. Methods This open-label, pragmatic post-marketing trial enrolled 1399 older adults to receive one dose of an approved commercially available quadrivalent influenza vaccine manufactured by Hualan Biological Bacterin Inc. (hereinafter referred to as “Hualan Bio”). Participants with contraindications for the vaccine were excluded, while poor health condition was acceptable. All vaccinated subjects experienced adverse events collection within 30 days and serious adverse events within 180 days post-vaccination. 25% subjects, selected randomly, underwent venous blood sampling pre-vaccination and 30 days after post-vaccination, for detecting antibody titers against each subtype of influenza virus by hemagglutination inhibition assay. The incidences of adverse events and antibody titers against each subtype of influenza virus were statistically analyzed using SAS 9.4. Results No grade 3 adverse reactions occurred within 30 days post-vaccination. The incidences of overall adverse reactions, local adverse reactions and systemic adverse reactions were 3.79%, 2.86% and 1.00%, respectively. No serious adverse reactions occurred within 180 days post-vaccination. There were 350 subjects who completed venous blood sampling pre-vaccination, among whom 348 subjects completed venous blood sampling at 30 days post-vaccination for immunogenicity assessment. With respect to hemagglutination inhibition antibodies against influenza viruses H1N1, H3N2, BV and BY subtypes, at 30 days post-vaccination, the seroconversion rates were 87.64%, 75.57%, 73.28% and 78.74%, respectively; the seropositive rates were 93.97%, 98.56%, 79.31% and 95.40%, respectively; and the geometric mean increase (GMI) in post-immunization/pre-immunization antibodies was 24.80, 7.26, 10.39 and 7.39, respectively. Conclusion One 15 µg/subtype dose of the vaccine had a good safety profile and elicited favorable immunogenicity among subjects aged ≥ 60 years. The results of this study indicate that Hualan Bio quadrivalent influenza vaccine strike balance between safety and immunogenicity, supporting unnecessity to increase dosage or inoculation frequency for further enhancing immunogenicity. Trial registration Registered on ClinicalTrials.gov. Registration number: NCT06334510. Registered on 28/03/2024 (retrospectively registered).

The operational temperature of the magnetorheological (MR) fluid retarder is usually over 80 °C, and it reaches 150 °C when heat dissipation doesn't function well. The high temperature will seriously affect the working efficiency of the MR fluid by decreasing the viscosity of the fluid, which affects the generated braking torque. For the analysis of the heat dissipation behavior of MR fluid retarder, an experimental study of a thermal management system using thermoelectric cooling (TEC) module with heat sink as the cooling unit was conducted. The variation tendencies of temperature for the TEC module were investigated during the working process of the MR fluid retarder using the TEC module and natural convection air-cooling. The performance of the MR fluid at the desired temperature was analyzed by applying one-dimensional thermodynamic model and a numerical calculation method. The influences of temperature on the performance of MR fluid retarder were analyzed by comparing the performance characteristics of the TEC modules with Peltier-Seebeck effect and natural convection air-cooling systems. The results indicate that TEC has a better effect on the MR fluid retarder performance compared to the natural convection air cooling systems. The TEC module coupled with heat sink achieved a higher heat transfer efficiency, maintained the working temperature of the MR fluid in the retarder, improved the retarder's efficiency, and maximized the braking torque generated. The proposed system will further enhance the longevity of the retarder and provide a platform for heat dissipation and cooling of automobile systems.