[A study on the hearing protection and intervention effects of silicone earplug usage among manufacturing workers].

Objective: To assess the efficacy of silicone earplugs in protecting workers exposed to noise in a typical manufacturing environment, and to provide training interventions for workers who do not achieve the anticipated noise reduction levels, as well as examining the spectral characteristics of earplug attenuation. Methods: From June to August 2022, a total of 294 noise-exposed workers in two manufacturing enterprises equipped with the same type of earplug were studied by cluster sampling method, by conducting questionnaire surveys, collecting data, fitting tests, and providing trainings, the current noise exposure levels of workers in the industry as well as the perception about the earplug were understood. Additionally, the attenuation before and after intervention in workplace were measured, the spectral characteristics of noise reduction were were described and compared. Results: The percentage of workers with Personal Attenuation Rating (PAR) of 0 is 32.7% (96/294), and the baseline pass rates are all below 60%. There were no significant differences in pass rates based on gender, age, noise exposure, education level, or cognition of earplug effectiveness. After adjusting the way that earplugs are worn or changing the type of earplugs, all workers were able to meet their noise reduction requirements. The median PAR improvement for both companies is above 10 dB. The noise attenuation of the earplug vary with frequency, with lower attenuation at 4 000 Hz and higher attenuation at 8 000 Hz, showing some deviation from the nominal values. Conclusion: The difference between the actual sound attenuation value of earplugs and the nominal value is related to the noise frequency. When using silicone earplugs, attention should be paid to the spectral composition of the noise in the workplace.

[Analysis on the characteristics of natural foci of hemorrhagic fever with renal syndrome in Gansu Province, 2012-2022].

Objective: To explore the characteristics of natural foci of hemorrhagic fever with renal syndrome (HFRS) in Gansu Province. Methods: The information of HFRS case data and rodent density monitoring data from 2012 to 2022 in Gansu Province were collected and epidemiological methods were used to analyze and investigate the characteristics of the epidemic focus. Results: A total of 869 cases of HFRS were reported, and four patients died from 2012 to 2022. The annual incidence rate is between 0.05 per 100 000 and 1.21 per 100 000. The cases were mainly distributed in the eastern, southeast, southern, and south of the central region of Gansu Province. Most cases were distributed between age 20-60, and the sex ratio was 1.85∶1 (564∶305). Most cases were farmers (61.80%, 537/869), herdsmen (19.79%,172/869) and students (6.33%, 55/869). In a wild rat-type epidemic focus,the incidence peak was from November to January of the following year. The natural rodent hosts of HFRS were Rattus norvegicus, Apodemus agrarius, and Mus musculus. The hantaan virus carriage rates were 2.79% (21/754), 0.42% (5/1 179) and 0.31% (2/643),respectively. Three epidemic foci were defined: two derived from the Pingliang and Gannan prefecture new outbreaks epidemic foci, respectively, while the other was the residue of the Dingxi epidemic focus. Conclusions: The southern, south of the central region and eastern part of Gansu Province are current key HFRS epidemic foci dominated by Rattus norvegicus, Apodemus agrarius, and Mus musculus, respectively. The virus genotype is hantaan virus. Case reporting areas should strengthen epidemic monitoring; the key epidemic areas should strengthen and implement various prevention and control measures to reduce the harm caused by HFRS.

[Application of bridging study design in preventive vaccine clinical trials].

Bridging study in vaccine clinical trials means a series of small-scale additional tests on the basis that the original safety and effectiveness of a vaccine have been confirmed in clinical trials, to prove that the characteristics of safety, immunogenicity and effectiveness of a vaccine are similar or consistent after component, population and immunization procedure change to other types which can extrapolate data from existing clinical trials. Compared with traditional vaccine clinical trials, bridging trials can promote the approval of vaccines to the market, accelerate the expansion of vaccine application, and promote the use of vaccines across regions and populations. In recent years, the application of bridge study design in vaccine clinical research has become more and more common. In order to better guide and promote the application of bridging trial design in the field of vaccine clinical research, we reviewed the design characteristics and application examples of bridging study design in vaccine clinical trials, and systematically elaborated the design ideas, key points and statistical evaluation methods of bridging study.