Epidemiology, risk factors, and vaccine effectiveness for SARS-CoV-2 infection among healthcare workers during the omicron pandemic in Shanghai, China.

Background: The COVID-19 pandemic has exposed healthcare workers (HCWs) to serious risk of infection. The aims of our study were to investigate the epidemiological characteristics and risk factors of SARS-CoV-2 infection among HCWs, and evaluate the vaccine effectiveness (VE) during the Omicron pandemic in Shanghai, China. Methods: Active surveillance of COVID-19 was performed among HCWs who worked in Shanghai General Hospital from December 2022 to January 2023. A case-control study was conducted by questionnaire survey to analyse the infection-related risk factors. A retrospective cohort study was explored to evaluate VE against primary infection. Results: During the Omicron outbreak, 2,008 of 2,460 (81.6%) HCWs were infected with SARS-CoV-2. The infection rate was higher in women, younger age groups, nurses and medical technicians. Among the 1,742 participants in the questionnaire, 1,463 (84.0%) were tested positive, and 95.1% of them developed symptoms. Most of the infections (53.0%) were acquired outside the hospital. The risk factors associated with higher odds of infection were working in the emergency department (aOR 3.77, 95% CI 1.69-8.38) and medical examination area (aOR 2.47, 95% CI 1.10-5.51). The protective factors associated with lower odds of infection were previous infection with SARS-CoV-2 (aOR 0.01, 95% CI 0-0.07) and receiving four doses of vaccines (aOR 0.40, 95% CI 0.17-0.97). For frontline HCWs, those who had oral-nasal exposure to coworkers were more likely to be infected (aOR 1.74, 95% CI 1.21-2.51). In VE analysis, the risk of primary infection was lower in HCWs who received the emergency heterologous booster (the fourth dose) during the epidemic (aHR 0.25, 95% CI 0.15-0.40), resulting in an adjusted-VE of 75.1%. Conclusions: In response to future pandemic, it is important for public health policies to aim at protecting HCWs through risk-differentiated infection control measures, strengthening personal protection and recommending vaccination to vulnerable individuals before the arrival of Omicron wave.

IL-8 reduces VCAM-1 secretion of smooth muscle cells by increasing p-ERK expression when 3-D co-cultured with vascular endothelial cells.

OBJECTIVE: The goal of this study was to investigate the crosstalk between vascular endothelial cells (ECs) and smooth muscle cells (SMCs) using a three-dimensional (3-D) co-culture model. In addition, the role of IL-8 in this crosstalk was investigated. METHODS: A 3-D co-culture model was constructed using a Transwell chamber system and type I collagen gel. Human umbilical artery smooth muscle cells (HUASMCs) were suspended in the gel and added to the upper compartment of the Transwell. Human umbilical vein endothelial cells (HUVECs) were then grown on the surface of the gel. The growth of HUASMCs was tested with a CFDA SE cell proliferation kit. IL-8 and other bioactive substances were investigated by ELISA and real-time PCR. The alteration of p-ERK expression related to the change in IL-8 levels was also examined by Western blot analysis. RESULTS: The proliferation rate of HUASMCs in the 3-D co-culture model was 0.679 ± 0.057. Secretion and transcription of VEGF, t-PA, NO and VCAM-1 in the 3-D co-culture model were different than in single (2-D) culture. When 3-D co-cultured, IL-8 released by HUVECs was significantly increased (2.35 ± 0.16 fold) (P﹤0.05) and the expression of VCAM-1 from HUASMCs was reduced accordingly (0.55±0.09 fold). In addition, increasing or decreasing the level of IL-8 changed the level of p-ERK and VCAM-1 expression. The reduction of VCAM-1, resulting from increased IL-8, could be blocked by the MEK inhibitor, PD98059. CONCLUSION: Crosstalk between HUVECs and HUASMCs occurred and was probably mediated by IL-8 in this 3-D co-culture model.

Passive cigarette smoking induces inflammatory injury in human arterial walls.

BACKGROUND: Epidemiological studies have shown that both active and passive cigarette smoking increase the risk of atherosclerosis. But very little is known about the biological processes induced by passive cigarette smoking that contribute to atherosclerosis. We observe the expression of a few of biological and inflammatory markers in human arterial walls in vitro which were treated with the second-hand smoke solution (sidestream whole, SSW), and discuss the possible mechanism of inflammatory injury induced by second-hand smoke. METHODS: The biological markers (platelet endothelial cell adhesion molecule-1, PECAM-1; alpha-smooth muscle actin, alpha-SMA; collagen IV, Col IV) and inflammatory markers (vascular cell adhesion molecule-1, VCAM-1; monocyte chemoattractant protein-1, MCP-1; interleukin-8, IL-8) of human aortal wall were tested by immunofluorescence staining. The levels of MCP-1 and IL-8 mRNA expression were detected by reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: No distinct difference was observed between SSW and the control group on the expression of biological markers as assessed by the light microscope. But the inflammatory markers VCAM-1, MCP-1 and IL-8 on the subendothelial layer and smooth muscle cell layers, which are near the endothelium of arterial wall, were strongly stained in the SSW group compared with the control group. Their fluorescence intensities in the 1:40 SSW group (VCAM-1: 0.35 +/- 0.04, MCP-1: 0.34 +/- 0.05, IL-8: 0.37 +/- 0.05) and the 1:20 SSW group (VCAM-1: 0.40 +/- 0.04, MCP-1: 0.52 +/- 0.09, IL-8: 0.51 +/- 0.07) were significantly stronger than the control group (VCAM-1: 0.12 +/- 0.04, MCP-1: 0.06 +/- 0.02, IL-8: 0.24 +/- 0.03) by semi-quantitative analysis of immunofluorescence (P < 0.001 vs control). MCP-1 mRNA expression in the 1:40 SSW (0.15 +/- 0.04) and the 1:20 SSW (0.19 +/- 0.06) group was significantly higher than in the control group (0.09 +/- 0.03) (P < 0.05, P < 0.01 vs control); IL-8 mRNA expression in the 1:40 SSW (0.64 +/- 0.12) and 1:20 SSW (0.72 +/- 0.13) groups was also significantly higher than that in the control group (0.49 +/- 0.13) (P < 0.05, P < 0.01 vs control) by RT-PCR. CONCLUSIONS: It is implied that a second-hand smoke solution induces the inflammatory reaction of the arterial wall by release of inflammatory factors even though there is no distinct structural change on the arterial walls under light microscope, indicating that passive cigarette smoking is related to inflammatory injury in human arterial wall and could be closely related to the early inflammatory stage of atherosclerosis.