Incidence and risk factors of COVID-19 in a tertiary hospital and the effectiveness of booster vaccination among health care workers: A retrospective cohort study, January 2020 to June 2022.

BACKGROUND: Health care workers (HCWs) face a higher risk of infection and may transmit pathogens to patients during a pandemic. This study aims to evaluate infection-control measures by analyzing the incidence and risk factors of COVID-19 and estimating vaccine effectiveness (VE) at a tertiary hospital in Seoul, Republic of Korea. METHODS: This study included 2,516 HCWs from January 1, 2020, to June 30, 2022. Data were analyzed to determine the incidence density and cumulative incidence; the results were compared by the age- and gender-specific standardized incidence ratios (SIR). VE was estimated with multivariate Cox proportional-hazard models as 1-adjusted hazard ratio × 100%. RESULTS: SIR indicated a lower COVID-19 risk in the hospital population than in the general Korean population (SIR, 0.81; 95% confidence interval [CI]: 0.76-0.87). Multivariate Cox analysis indicated that, compared to doctors, nonmedical service supporters and other HCWs (excluding doctors and nurses) were high-risk groups (adjusted hazard ratio [95% CI], 1.72 [1.04-2.83] and 1.76 [1.20-2.58], respectively). Compared to the outpatient unit, the emergency department was a high-risk department (1.70 [1.16-2.50]). The VE of the booster dose was 55.47%, compared to no or incomplete vaccination (95% CI: 22.63-74.37). CONCLUSIONS: Besides encouraging HCWs vaccination, effective infection-control measures should target high-risk groups and departments.

Relative Effectiveness of COVID-19 Vaccination in Healthcare Workers: 3-Dose Versus 2-Dose Vaccination.

The omicron variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is known to have high infectivity and is more likely to evade vaccine immunity. However, booster vaccination is expected to strengthen cross-reactive immunity, thereby increasing the vaccine effectiveness (VE). This study aimed to evaluate the relative VE of the 3-dose (booster) vaccination compared with the 2-dose primary series vaccination in healthcare workers during omicron variant-dominant periods. During the omicron-dominant period from February 1, 2022 to February 28, 2022, a 1:1 matched case-control study was conducted. Healthcare workers with positive SARS-CoV-2 test results were classified as positive cases, whereas those with negative results served as controls. Compared with the 2-dose primary series vaccination, booster vaccination with mRNA vaccine showed moderate VE (53.1%). However, in multivariate analysis including the time elapsed after vaccination, the significant VE disappeared, reflecting the impact of recent vaccination rather than the third dose itself.

Injectable Human Hair Keratin-Fibrinogen Hydrogels for Engineering 3D Microenvironments to Accelerate Oral Tissue Regeneration.

Traumatic injury of the oral cavity is atypical and often accompanied by uncontrolled bleeding and inflammation. Injectable hydrogels have been considered to be promising candidates for the treatment of oral injuries because of their simple formulation, minimally invasive application technique, and site-specific delivery. Fibrinogen-based hydrogels have been widely explored as effective materials for wound healing in tissue engineering due to their uniqueness. Recently, an injectable foam has taken the spotlight. However, the fibrin component of this biomaterial is relatively stiff. To address these challenges, we created keratin-conjugated fibrinogen (KRT-FIB). This study aimed to develop a novel keratin biomaterial and assess cell-biomaterial interactions. Consequently, a novel injectable KRT-FIB hydrogel was optimized through rheological measurements, and its injection performance, swelling behavior, and surface morphology were investigated. We observed an excellent cell viability, proliferation, and migration/cell-cell interaction, indicating that the novel KRT-FIB-injectable hydrogel is a promising platform for oral tissue regeneration with a high clinical applicability.

Identification of peptide based B-cell epitopes in Zika virus NS1.

Zika virus (ZIKV), a mosquito-borne flavivirus that has recently emerged globally, poses a major threat to public health. To control this emerging disease, accurate diagnostics are required for monitoring current ZIKV outbreaks. Owing to the high nucleotide sequence similarity and cross-reactivity of ZIKV with other members of the Flaviviridae family, discrimination from other flavivirus infections is often difficult in endemic areas. ZIKV NS1 induces major virus-specific antibodies and is therefore utilized as a serological marker for ZIKV diagnosis. To identify ZIKV specific epitopes for clinical application, 33 NS1 peptides that are 15-30 amino acid in length covering whole NS1 were synthesized and analyzed linear B-cell epitopes with 38 human serum samples (20 ZIKV-positive and 18 ZIKV-negative). As a result of screening, eight epitope regions were identified. In particular, the Z8 and Z14 peptides located in the ß-ladder surface region showed higher levels of binding activity in ZIKV-positive sera without cross-reactivity to other flaviviruses. These identified sensitive and specific epitopes provide a tool for design of diagnostics and structure-based vaccine antigens for ZIKV infection.

Covalent Functionalization of Multi-Walled Carbon Nanotubes Surface via Chemical Treatment.

Due to the strong hydrophobic and van der Waals interactions between individual carbon nanotubes (CNTs), these particles easily aggregate with themselves. When CNTs were introduced into a polymer matrix as a filler, aggregations formed that can adversely affect the mechanical and thermal properties of polymer/CNTs composites. To prevent aggregation, covalent functionalizations via chemical treatments using H2SO4/HNO3, H2O2/H2O and a silane coupling agent(STX)-glycidoxypropyltrimethoxysilane, GPTMS) on the CNTs were chosen in this study. Moreover, the effect of the functional groups on the solubility of CNTs in tetrahydrofuran (THF) was investigated. The surface-modified multi-walled carbon nanotubes (MWCNTs) were also characterized and compared with pristine MWCNTs using several techniques. Morphology changes in surfacemodified MWCNTs were observed by Raman spectroscopy and Field-Emission Scanning Electron Microscopy (FE-SEM) images. Qualitative analyses of the functional groups on the surface-modified MWCNTs were performed by Fourier Transform Infrared Spectroscopy (FT-IR). Additionally, quantitative analyses were performed by X-Ray Photoelectron Spectroscopy (XPS), Energy Dispersive Spectroscopy (EDS), a titration method and Thermogravimetric analysis (TGA).