The Hand, Foot, and Mouth Disease Sentinel Surveillance System in South Korea: Retrospective Evaluation Study.

Background: South Korea has implemented a hand, foot, and mouth disease (HFMD) surveillance system since 2009 to monitor incidence trends and identify disease burden. This nationwide surveillance involves a network of approximately 100 pediatric clinics that report all probable and confirmed HFMD cases. Following the COVID-19 pandemic, infectious disease surveillance systems must be evaluated to ensure the effective use of limited public health resources. Objective: This study aimed to evaluate the HFMD sentinel surveillance system in South Korea from 2017 to 2022, focusing on the transition period after the COVID-19 pandemic. Methods: We retrospectively reviewed the HFMD sentinel surveillance system from the Korea Disease Control and Prevention Agency using systematic guidelines for public health surveillance system evaluation developed by the US Centers for Disease Control and Prevention. We assessed the system's overall performance in 5 main factors: timeliness, stability, completeness, sensitivity, and representativeness (ie, the age and geographic distribution of sentinels). We rated these factors as weak, moderate, or good. Results: Our study showed that the completeness, sensitivity, and age representativeness of the HFMD surveillance performance were temporarily reduced to moderate levels from 2020 to 2021 and recovered in 2022, while the timeliness and geographic representativeness were maintained at a good level throughout the study period. The stability of the surveillance was moderate from 2017 to 2021 and weak in 2022. Conclusions: This is the first study to evaluate the HFMD surveillance system after the acute phase of the COVID-19 pandemic. We identified a temporarily reduced level of performance (ie, completeness, sensitivity, and age-specific representativeness) during the acute phase of the pandemic and good performance in 2022. Surveillance system evaluation and maintenance during public health emergencies will provide robust and reliable data to support public health policy development. Regular staff training programs and reducing staff turnover will improve HFMD surveillance system stability.

Three-Dimensional Tungsten Disulfide Raman Biosensor for Dopamine Detection.

Two-dimensional (2D) transition metal dichalcogenides (TMDCs) are promising materials for detection of biomolecules due to their large surface-to-volume ratio. However, their poor response to the cellular environment hinders the realization of high-performance 2D TMDC sensors. Here, we present a hierarchical Raman scattering sensor consisting of the WS2 directly grown on an array of three-dimensional (3D) WO3 nanohelixes (NHs) by sulfurization. Both the adsorption of biomolecules and the proliferation of cells are significantly promoted for the 3D WS2/WO3 NH sensor compared to the control sensor with sulfurized WS2 on 2D WO3 film, leading to much enhanced sensitivity to dopamine. In addition, according to the in vitro test using PC12 cells, the 3D WS2/WO3 NH sensor shows a significant increase in hydrophobicity and Raman frequency shift, indicating that both the attachment of cells and the detection of biomolecules are improved.