E ffective contact tracing is critical to controlling the spread of coronavirus disease (COVID-19) (1). South Korea adopted a rigorous contact-tracing program comprising traditional shoe-leather epidemiology and new methods to track contacts by linking large databases (global positioning system, credit card transactions, and closed-circuit television). We describe a nationwide COVID-19 contact tracing program in South Korea to guide evidence-based policy to mitigate the pandemic (2). The Study South Korea's public health system comprises a national-level governance (Korea Centers for Disease Control and Prevention), 17 regional governments, and 254 local public health centers. The first case of COVID-19 was identified on January 20, 2020; by May 13, a total of 10,962 cases had been reported.

Poly (vinylidene fluoride) (PVDF) matrix hybrid nanocomposites, featuring ferroelectric barium titanate (BT) nanoparticles and multi-walled carbon nanotubes (MWCNT) embedded in the polymer, were fabricated by a miscible-immiscible coagulation method followed by hot pressing. SEM images showed good distribution of the ceramic nanoparticles with very little particle agglomeration. The conductive MWCNT increased the charge storage ability of the matrix polymer by serving as a polarized charge transport phase for the ferroelectric nanoparticles, while the small MWNT amounts used prevented the formation of conductive networks. The simple processing method utilized resulted in composites with high real permittivity and low dielectric loss over a wide range of frequency (10 Hz to 1 MHz). The dielectric properties of the polymer matrix nanocomposites with hybrid fillers (BT with and without MWNT) were improved by optimizing the synergistic effects between the charge storage behavior of the ferroelectric phase and the charge transport behavior of the conductive phase. The best combination of real permittivity and dielectric loss properties (71.7 and 0.045 respectively) were obtained for the nanocomposites containing 37.1 vol % of BaTiO 3 and 3 vol % of MWCNT. In addition to achieving reliable dielectric properties, the nanocomposites also displayed flexibility making these composites potentially useful for many flexible electronic devices and electrostatic energy storage devices.

We report the first 7,755 patients with confirmed COVID-19 in Korea as of March 12 th , 2020. A total of 66 deaths have been recorded, giving a case fatality proportion of 0.9%. Older people, and those with comorbidities were at a higher risk of a fatal outcome. The highest number of cases of COVID-19 were in Daegu, followed by Gyeongbuk. This summary may help to understand the disease dynamics in the early phase of the COVID-19 outbreaks, and may therefore, guide future public health measures.

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Transmission of pathogens via respiratory droplets can spread infections such as COVID‐19. Wearing a mask hinders the spread of COVID‐19 infection and has become mandatory in some cases. Although most masks are affordable and disposable, continual daily replacement is required due to their performance deterioration caused by washing and contamination. Hence, a urethane‐reactive coating material comprising perfluoro‐tert‐butanol‐hexamethylene diisocyanate is developed with highly hydrophobic and oleophobic properties to functionalize a polyurethane‐coated fabric to bestow high breathability, durability, reusability, and protection ability. Its functions are maintained after scratch and wash testing, and its air permeability and water vapor transmittance rate (necessary for respiration) are unaffected. Its filtration efficiency of water droplets containing 100 nm polystyrene particles (similar in size to SARS‐CoV‐2) is increased due to its highly hydrophobic properties. In addition, it inhibits the adsorption of bovine serum albumin, the spike protein of COVID‐19, and Staphylococcus aureus and Pseudomonas aeruginosa.